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DC-DC Stepdown regulator for CPU MOD
Saving power/heat using stepdown regulator instead of cooling resistor

New MessageDC-DC Stepdown regulator for CPU MOD (modified 0 times) uiucgeek
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Hello,

I have been reading the threads on the CPU MODs, and while the cooling resistor is a very economical idea, it turns a lot of power into heat. The board already does dc-to-dc conversion to step down from 19V to 3.5/3.3 used on the CPU. Although it should be possible to change this regulator, I wonder if an external regulator, in the molds of the powerleap, would not allow the use of the supplied power brick and current limiting resistor. The LTC1736 is a good candidate for stepdown regulator. My question to the gurus: If we lift Q16 completely, is it possible to power the CPU core from its pads?

The datasheet for the LTC1736 is in http://www.linear.com/prod/datasheet.html?datasheet=486

02-13-2001 13:27:29

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Turbo3
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Absolutely, and at least one person has gone that way. Maxim sells an evaluation unit for their switch module but it costs around $60 if they will sell it to you. Designing one yourself is tricky due to the high current levels (6-8 amps). You need a custom printed circuit board. So yes if you can build or buy a switching regulator that outputs the required voltage (1.5 to 2.0v) it is easy to hook in. You can either go from the 19v or I have seen one that goes from 3.3v to 1.8v from Datel (http://store.datel.com/cgi-bin/datel.storefront/3a89b1a301ad2234274c401c4e47065f/UserTemplate/1?BodyContent=newpower#power1). The Datel one is nice and goes for $29 in OEM quantities but they never returned my phone mail for small quantites. Anyone up for a group buy of these?
02-13-2001 15:24:28

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) uiucgeek
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I looked at the datel and it is great. It is a very small package, and you can even put a trimpot and change Vcore. I will request samples - count me in for the group buy.
02-13-2001 17:31:31

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) jonluc
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I can't believe that this hasn't been looked at in detail before. Great idea guys. I'm in.
02-13-2001 21:09:31

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Turbo3
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Datel even has an online system to buy sames using credit cards but they only list the older 2 amp DC-DC converter. They never answered my email on when the 10 amp one would make it to the online page.
02-14-2001 00:41:01

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) mp3boombox
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trubo3 little off tipic, I'v not seen you on ICQ so i'll try to trranslate the message this way. The floppy drive i sent to you, I hope you didnt disgard it because I'v got the info to make it work corretly.

The reason you got a BLUE screen is because the little plastic ribbon cable going to the metal connector i want back. This floppy drive is DESIGNED FOOR an older IBM laptop. That little cable has a totaly different PIN out. If you take out the floppy unit its self and look on the underside, by the ribbon connector only on the under side you should see a labling of PIN 1-26, 1-26 is the exact same as any standerd FLOPPY drive pinout is. Only catch is that the pins 1 3 5 are all connected togeather. These are the +5v power pins and as you know already 13-25 are all ground. If you wire it up like this the FLOPPY will work on any standerd FLOPPY drive controler. I'v tryed a few different computes and it works just fine.

The only thing I'm missing now is the connector from that one i gave to you AND the patched bios you guys are working on.

i'LL REPOST THIS ON THE real floppy drive tipic.

02-14-2001 14:30:25

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) mp3boombox
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OH also heh ment to put this in the other message, BUT I strongly stand behind this MOD. It would be nice to not need lots of EXTRA cooling due to the q16 chip. Plus saving power by not using the dropping resistesr would make OVER clocking an easyer TASK. MINUS THE Q16 THE ONLY OTHER parts on the IO that get realy HOT at the 100fsb rage is the SYSTEM memory cpu and chipset. CPU and mem are the next in line for heat after q16.

If the DC-DC chip's can be made into a reality via a GROUP buy. Hehe i bet this would SOLVE a lot of peoples power/heat problems NOT being able to go over 333mhz with teh AFK cpu's. Or the other people whom are using k6-3's and cant get to or above 450mhz. I bet that with one of them and my second CPU cooling MOD. I could get to 550mhz STABLE. FOLKS THATS 100MHZ OVER CLOCKED. I'M CURRENTLY DOING 75MHZ OC JUST FINE.

I forget what the power savings would be BUT this MOD could also be the difference between a USB or extra devices like FLASH card, CDROM, EXTRA hard drive, or floppy drive (when complet), which suck up power working or NOT working.

One of the things i seem to be having problems with is running 2 USB devices at the same time. Some things work fine with each other BUT others acording to my multi meter sais that I'm comming CLOSE to my POWER bricks limate.

Thats an other thing I'm going to put some efferent into this weekend is seeing what i can do to squeaze some more JUICE out of the power brick, with as little moding as possable. COOLING helps BUT not as much when you are exceeding the devices power limate.
On a gues I'm going to asume one of the mosfets is to close to its set limate, OR phisical limate.

If this is the CASE it will be as simple as a component change OR a mosfet change.
IF any one know's the answer to this already please contact me.

02-14-2001 15:44:39

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Turbo3
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Perhaps BadFlash with his buying power can pull this one off too and make it available to all.
02-14-2001 17:30:21

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) SirDag
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My fellow hackers:

I have added a second usb port, did the rs232 hack, did the processor hack
(with the cooling resistor) added a fan and hd, added an external cd via
ribbon cable, added 5v to the rs232 port for the external delorme gps unit.
BUT, I have clocked the cooling resistor at over 300 degrees!!! thats without
the rf shield on.. and not in a hot car... SO..

I think this would solve a lot of problems.... it really makes sense...
why waste all that juice on HEAT? If anyone gets a line on the gizmo.. let us know.
I'll be one of the first in line to give it a try....

regards,
SirDag

02-27-2001 17:30:46

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) starfish
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Sir Dag,

Just Wondering what CPU, & what Speed You were Running it @ ???

(AMD K6 III+ 450Mhz @ 600Mhz ) ???

02-27-2001 17:45:49

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) SirDag
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AMD k6III+450 booting at 3x100, k6clk'ed up to 450 in wine doze 98se.

It runs stable, but you could cook a steak on this thing....

I was just cruzing the site that makes the 3.3v to 1.8 or 2.5v gizmo.. cool.

SirDag

02-27-2001 18:08:02

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) deadbolt
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Using the email link on Datel's page to order sample units I got an "undeliverable" message back. So; If at first you don't ..... try again.
03-02-2001 10:07:10

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) BadFlash
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Long discussion with Datel today. I've got a couple of samples ordered, but they won't be here until March 10. These beasts are pretty pricey and an adapter board will have to be made. They Measure 1"X2"X.5" so we should be able to fit them in. They will need a bypass capacitor and an inductor to filer out the power supply ripple. By the time were done with this we will be talking in the realm of $75. Any interest at that price or did I just scare all the kids off the street?

Turbo3- you got time to do some prototype/testing work if I send you one of these?

03-02-2001 11:25:18

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) cerulean
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Has anyone looked at using a VRM. They're available on Ebay for $35 (or less). Pump in 5V, set a 5 bit value to get the voltage out (1.3 to 3.5V). It looks like they're around 83% efficient, so the strain on the power supply would be minimized.

http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=1218812026

It would have to be wired in and it may be a bit big to fit in, but it seems pretty straight forward.

03-02-2001 17:14:33

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) rscott
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Using a VRM does work. I bought some from justdeals awhile back, and used the VRM info from intel's website to figure out how to hook it up. The downside to this implementation is that it requires both 12V and 5V to work, doesn't fit inside the iopener case, and I couldn't figure out how to get the iopener to power sequence the VRM properly.

BTW, this was on a V1 iopener. I lifted q16, and rigged for 100 MHz FSB. Was able to get an AMD K6-3+ to run at full speed.

I'd definitely be interested in a better solution! National Semiconductor also has some parts that would be interesting, though they require quite a few external parts.

Rob

03-12-2001 19:21:31

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Fatal
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Just to reply to BadFlash. I would be interested in one if not two at that price. Let us all know how the experimentation with the samples goes.
03-13-2001 17:25:38

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) BadFlash
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Got my sample today. I've called Datel back to find out why they only sent me 1 when they promised 2. I need to do some measuring and see if this will fit in the area above the SODIMM.
Got to be sureit does not interfere with the IMOD3 or the RS-232 board, so there are not a lot of options. The module is 1" X 2" and is about .4" thick.

Turbo3- I'll send you one if I get 2.

03-15-2001 13:40:34

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) BadFlash
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They are sending me a 2nd module, so Turbo3, you'll be getting yours. I'll send you details of what I've figured out this weekend.
03-16-2001 11:26:07

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Turbo3
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Ok, Thanks.
03-16-2001 14:31:46

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) rnunes
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Hi BadFlash,

Been reading your post. I just added a DC-DC coverter in place of the Mosfet. I used the Power Trends PT6702 (3.5V -> 2.05V). Works great, stays nice and cool even at 500Mhz (AMD-K6III+). Mounts nicely using one of the passice heatsink holes between the processor heatsink and SODIMM. Now I just have to add the RS-232 and Compact Flash Mods and it is finally complete. I will post pictures as soon as I take them.

Rob

03-16-2001 20:38:43

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) palmhacker
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Rob,

Do you know what these Power Trends PT6702's cost in small quantities? I did find Power Trends website and ordered a sample but if this works I'd like to get more than one. It looks like this could be a pretty slick solution.

http://www.ti.com/cgi-bin/sc/pt_samples.cgi

Jim

03-16-2001 22:01:36

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) deadbolt
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This looks to be a sweet solution. A bit spendy, but for more efficient use of current, it should be worth it. One other concern is the heat generated in the 3.3 volt power supply and in particular the large-ish inductors that normally heat up. Sorry I don't have a component number. I am looking forward to a hack that will get my K6-3+ up to at least 333 or better with passive cooling.

The TI component seems to have lots of pins, I guess for programming the Vout. Does this require many external components and how much space did you loose with it ? Pics would be great !

03-18-2001 17:09:43

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) rnunes
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Hi,

Finished putting in the DC-DC converter. I not sure how much they cost, but I will try to find out. Here is a
picture. I took off all the pins and soldered a little dip switch (to adjust the voltage) underneath it. Notice how one of the pins fits nicely in the old passive heatsink hole. I am going to put a piece of black electrical tape over the row of pins to ensure they don't short to the metal case. My next step is to somehow get the fan controller on the northbridge working or put my own controller on. When it is sitting on the counter and the LCD turns off I want to slow down the fan for less noise. This runs stable at 600 Mhz and bearly gets warm(The DC-DC). I am going to do some temp measurements soon.

Rob

03-18-2001 20:45:00

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) deadbolt
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Rob,
How did you bump it so high without killing the power brick ? Is this a K63-450 running that high ? I am definately interested to hear details of what mods you have done to achieve this. A new thread maybe - u breaking the I/O speed record ?
03-18-2001 23:39:32

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) dukiedumb
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Hello,

Arrow.com shows stock of the PT6702C, which I believe is the horizontal surface-mount
package for $35.67 plus $19.00 shipping, (doh!) single quantity. I believe any of the package styles should work.
Switch-power also has some possibilities http://www.switch-power.com/products/hdlv/sc15a.htm
The dimensions are 3" X 0.735" X 0.42, a bit large, perhaps.
The SC10A would be nice also, if it were available in 3.3 V.
I have not found pricing on any of these, however.Still looking for other options.
Just curious Rob, what voltage(s)were you running the CPU at? Also, did you need any extra capacitors or inductors?

Later all!

03-19-2001 17:52:03

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) mp3boombox
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welp that beats my IO running at 525mhz. hehe its about time someone beat me, also I'm wondering what have you done to the CPU if any thing?? becuase the BEST hack for the AMD k6 cpu's is to remove the HEAT trap err (cap) On the cpu. so you expose the CORE its self which resembles the mmx p233 cpu's. you can drop the CPU temp by as much as 6-10 degrees F. but its a resk to the CPU to remove the cap phisicly.

the reson you get such a high result is due to the nature of the CAP. its for one aluminum so it doesnt transfer HEAT as well. 2 its glued down with 4 splaches of a rubber like expoxy in 4 corners. 3 there is a small void between the core and the heat cap. with a CHEEP filler to transfer the HEAT.there for its better to just do direct contact witht he CPU when it comes to COOLING the chip. as is i can get to 550mhz EASY on my io for about 20min till the the heh dripping resisters and the HOT ass q16 regulator worm up a little past the boiling point.

ALSO as is running at 525mhz my MEMORY gets extreamly HOT. I mean LIKE do not tuch hot!
Rnunes I'm coures to find out what you have for memory?? and what temp your memory is running at after 40min of intense useage of the IO? the best usage would be like playing a DIVX MOVIE which requires cpu decoding. This does a LOT of MEMORY retunes due to the VIDEO SMI with the system memory.when i get one of the dc-dc adaptres and rig it up I'll be intrested to see what else on the IO cools down.


OH OH OH OH also what is the highest speed you can BOOT your io at??? due to the fact that you have more power available on boot up due ot the DC-DC and non being lost due to dropping resisters are you able to boot up at speeds past 300mhz 3x100??? this will be an intresting result? also with WHAT adapters can you boot up with at higher speeds I.E. usb devices.

03-19-2001 18:17:53

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) rnunes
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Hi,

I am running the core at 2 volts. I added one 100uf tantalum cap on the output, you can see it in the picture (yellow object uderneath) and a 4.7K pullup for the fault line.

Mp3boombox I have not put the unit fully back together, due to my fan controller addition. I think your memory and CPU are getting too hot due to Q16 and the voltage dropping resistor. I have a stick of DELL 128Meg 100Mhz memory in it and does not get that hot. I have not tried booting above 3x100Mhz, I will try it. After it boots I used k6clk to crank it up to 6.0. I mounted a linksys USB ethernet adapter inside it, 6 Gig drive. The only real test I have done is streaming mp3's off my websurfer. Once the fan controller is in, and some thermal measurements are made, I plan to seal this up and put it on the kitchen counter where it belongs. Its been apart too long. I plan to experiment with my other Iopener and now that the northbrige spec is released finally try to add the external cache, since I already have all the parts.

Rob

03-19-2001 19:21:37

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) BadFlash
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Turbo3- contact me off line. Your old E-mail address must be no good.
03-21-2001 11:13:12

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) mp3boombox
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You have the parts for the external cache????? DO tell

berinc@acadia.net

03-21-2001 14:38:31

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Tinman2
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rnunes

or anyone who knows, what is meant by the "fault" line, is this the ground?
rnunes, maybe you could post the pins you used off of the PT6702,
it would be helpful.
I am getting one of these after seeing how well it went in when I saw your picture.
Thanks in advance for your time...
Tinman

03-22-2001 02:35:28

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Programmer
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The parts for the l2 Cache are pretty common on pentium motherboards.. I stripped the parts off of one and will be attempting to get it working at some point in the future myself.. with any luck, it will be recognized by the bios and will not require a bios fix.. .. U202 should have plenty of parts for this lying around.. :) .. BTW try to shoot for 512Kb, and make sure you get the tag ram as well..
03-22-2001 07:37:46

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Kudzu
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rnunes, I'd like to second Tinman2's request.

I just got my PT6702, and a little more detail on what goes where would be greatly appreciated.

FYI to those considering the PT6702:

According to the catalog, the PT6520 supports an output voltage of 1.2-2.53 (6-12A), which would support a greater range of processors. You may want to consider it as an alternative if you want to run something other than the k62+ or k63+ version.

Kudzu

03-22-2001 15:35:19

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) rnunes
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Hi Tinman and Kudzu,

Here what I did.
1. Remove all the pins with the soldering iron on the PT6702 (pins 1-23),
you are going to solder right to the pads underneath the part.
2. I pulled up to Vin (3.52 Volts) thorough a 10K resistor pin 2 (power good), since its open drain.
3. Short with wire wrap wire pin 7 to pin 13 to pin 14.
4. Wire up a dip switch to pins 4,5,6,7 or just ground them all (for 2.05 volts), ground is pins 14-18
5. Remove Q16
6. Connect three 22 AWG or bigger wires, one to pins 10,11,12, one to pins 14,15,16, and one to pins 21,22,23.
7. I had to dremel the heat sink leg and bend it alittle to get it to fit in the old passive heatsink mounting standoff,
and fit flush against the tenmax fan.
8. Connect the wire Vin (pins 10,11,12) to the Big square pad of Q16.
9. Connect the wire Gnd (pins 14,15,16) to Gnd, I used the big square pad with the mounting screw in it,
to the left of C154.
10. Connect the wire Vout (pins 21,22,23) to C154 C155 pads closest to the processor.
11. Put a piece of electrical tape, or mylar over the pins so it won't short to the metal shield.

Hope this helps. Any questions, email me.

rnunes

03-22-2001 18:24:43

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) JohnQPyro
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Rob,

Just recieved the PT6702A in the mail via FedEx (WOW) !!
Do you have maybe a few more pictures of your hack..??
Also in the previous post you indicated "Pins 21,22,23 to C154 C155"
Is that one wire to BOTH Tabs ??

Thanks for the help, and Big Kudos on the Hack....

JohnQ

03-29-2001 13:01:49

New MessagePT6702A is it ! (modified 0 times) Tinman2
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This Power Supply is great, and it's a free sample !!!
I am running at 600 Mhz 6x100 on a AMD K6III+ @ 2 volts core.
rnunes: thanks a million for your help, this worked out well.
I mounted it on the outside edge of the IO using the speaker clamp to hold it in place,
I also used a spare clamp I had to mount the opposite side to an unused frame lug.
The temps are 77F..mainboard , 103F..cpu and barely warm on the PT6702A, after running speed disk for 10 minutes.
Sandra 2000, 1393-MIPS 745-MFLOPS while using a usb nic.
For some reason, on one of the reboots... It lost the usb.
I am totally satisfied with this fun and free upgrade !!!
going to look into the usb problem soon.

Tinman

03-31-2001 19:27:34

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) mdetz
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So, everyone is just getting them as free samples from this company, or is there another source?
04-01-2001 14:49:05

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) mp3boombox
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How long did it take for you guys to get your samples??? i orderd mine from that link on the 17th of march, and have not recived any thing yet???
04-03-2001 13:23:50

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Glitch
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mp3boombox: I ordered my samples on 3/22, got a call from the PowerTrends salesperson on 3/23, returned the call and answered a few questions on 3/26. The samples were shipped on 3/28 and I received them on 3/30.

The questions were not very specific. I think they were just to verify that I was ordering the correct parts. HTH.


Glitch
Electronics run on smoke, if you let the smoke out they won't work
04-03-2001 14:38:41

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) mp3boombox
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welp this just sucks for me then because i work during the day 5days a week mon-fri. and I'm shure that place is closed.

would it be posable for someone to get samples for me??? because I'll never have a mon-fri off unless its a holiday!! :) though i get EVERY holiday off got to love working in a LAB

WWW DOT JAX DOT ORG

04-04-2001 13:28:30

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Enduser6
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Requested PowerTrends for a free sample, got a call to confirm address and looks like its on its way. Does anybody have a website or pictures on step by step procedure on this CPU mod? Do I have to install the SW SMT (I believe is SW4) for the clock multiplier? How about the resistor? Kindly help, I not that technical but have a steady hand and could read instructions. So far I did the HD LED mod (nothing to brag about) and duplicate a MOD3 board...I guess I could both on my resume.
04-04-2001 14:40:24

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Glitch
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mp3boombox: I don't think that I would be able to get samples for you, I'm guessing that I'm all sampled out as far as PowerTrends is concerned. I can give you the name and number of the salesperson that I spoke to. Send me email.
Glitch
Electronics run on smoke, if you let the smoke out they won't work
04-04-2001 14:41:03

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) mrblack51
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rrunes: did you add the resistor in parallel to r302?

to Glitch or anyone else who was able to get samples: did power trend ask you the following, and if so, what did you tell them?

1. What is the application the sample will be used in?
2. What is the estimated annual volume of your project?
3. When do you plan to begin production?
4. What company do you work for?

I was looking forward to the traditional 450 upgrade, but I would rather do this, as it seems to be a superior solution. Thank you in advance.

04-05-2001 20:58:21

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Tinman2
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I am sure I'm sampled out also. As for info asked by Power Trends, they didn't ask as much as I offered. Tell them your modifying a chitload of puters at a university or something, from 3.3v to 1.8v when they call or when you return their call.

Per rnunes...

mrblack51: the 10k resistor went between pin 2 (PwrGood) and pins 10,11 & 12 (Vin) of the PT6702.

JohnQ: Put Vout across both caps on the iopener (C154 and C155).

enduser6: rnunes has a picture link in his 2nd reply. With that and what he stated above should be enough to get you through the install. Power into the PT6702 from the IO mobo is on the large solder pad that acts as a heatsink when you remove Q16.
pins 4,5 & 6 should go to one side of a momentary or dip switch and pin 7 to the other for voltage adjusting, or wire them straight to ground (pin 7) if your happy with 2.05 volts. Get the pdf file on it and read it, it's helpful.
I could try to get a picture of mine and email it to you if you like. I have to put on a new fan soon and could snap one then.

As for the 600mhz, I'm no longer running that fast, my iopener kept loosing the usb.

Tinman

04-05-2001 22:31:51

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) BadFlash
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I had a nice talk with PowerTrends this week. I'll be working on a production mod board soon if this works out. They said they were nearly out of samples and when they run out it would be another 3 weeks until they had more. I'm getting the surface mount version to check out and am getting a few other goodies too. The have two other modules that have some promise. One is a 19V to 5V power supply and another is a 19V to 12V power supply. They both have logic to turn on, so it looks like an easy fix to supply 5V/12V from inside the box with this method for those external 40 pin IDE devices. The IMOD3 has that 40 pin connector just begging to get used...
04-06-2001 09:41:57

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Enduser6
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Tinman: Thanks for the info. I will be trying to draw up a schematic once I get the
PT6702 with all the info you guys posted here. I got the clock multiplier and bus speed all set up, I use ordinary dip switches (from old boards - the one you slide in the black thing to short them) and hair thin insulated wire wrapping stuff ...amazingly it works. I order a K6 II-450 for $30. Okey while I am waiting, I need to know where to measure the Vcore voltage (Oscope,DMM, spectrum analyzer etc I got them all), without the CPU plug in if possible (I know its in the bios). From previous hacks, I think I read at U16 pin 3 after its been lifted, is this a good place to measure it. BTW I got a V1.
04-06-2001 20:18:52

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Glitch
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Has anyone determined a good place to hook up pin #8 (Standby)? With the i-Opener off and pin #8 left open the core voltage will be supplied to the CPU. Without the fan running the processor heats up.

If you are experimenting with the PT6702 you may want to keep an eye on your processor temp. I left my i-Opener off, but plugged in, while I went to look something up. When I came back the processor was hot enough that I thought I might have fried it. Luckily it was OK.


Glitch
Electronics run on smoke, if you let the smoke out they won't work
04-06-2001 21:38:17

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) JohnQPyro
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Glitch,

So we just hookup one of the 12v Lasagna fans to this location on the IO....
http://sites.netscape.net/djbarry0/images/12V_On_Board.jpg
and
http://sites.netscape.net/djbarry0/images/Power_Connections.jpg

See this thread for more info.
http://www.linux-hacker.net/cgi-bin/UltraBoard/UltraBoard.pl?Action=ShowPost&Board=technical&Post=2161&Idle=0&Sort=0&Order=Descend&Page=0&Session=johnqpyro.98672030514849

And let it run..... probobly a bit loud... Just a thought.

04-08-2001 02:00:56

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Enduser6
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Glitch: Just got my PT6702 and set it up on a workbench with an external power supply, works great. I am getting ready to set it up in my IO, just waiting for the CPU. Any news what to do on Pin 8 (Standby)? Thats appears to me a major problem for me if I have to use the PT6702 for my CPU mod.

Thanks

04-10-2001 20:56:30

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Glitch
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JohnQPyro: Your idea should work. I'm not sure about what happens to the CPU if you turn off the 3.3v I/O and not the Vcore. So far it doesn't seem to have hurt anything, but I haven't let it sit in this condition for more than a few minutes. I really want to turn off the Vcore and the fan. I like silence.

Enduser6: I have not found a good place for a simple hookup for pin #8. I was hoping that someone that is more familiar the i-Opener power scheme would know of a good spot to connect.

I am resorting to adding extra circuitry to do the job. I have parts on order to try it two ways. The first is to use an TTL inverter tied to the 5v line and a Schottkey diode. This is similar to what is listed in the PT6702 data sheet. The second method is to use a depletion mode MOSFET with the gate tied via a resistor to either the 3.3v or 5.0v supply. The drain/source would be connected to pin8/gnd, respectively. I don't have much experience with MOSFETS, but I think this will work. I'm sure I will learn something from trying. The parts should be in later this week and I hope to have them installed over the weekend.

My solutions aren't very inspired. I'm still hoping that someone comes up with something better.


Glitch
Electronics run on smoke, if you let the smoke out they won't work
04-10-2001 21:34:13

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) JohnQPyro
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I DID IT !!! My V5 IO is running at a MUCH cooler 550mhz. I installed the PT6702 a few
days ago, and have yet to do any real testing. Board temp went from a scorching 158f to a
wonderfully cool 92f. Now keep in mind that i have'nt fired up Quake 3 yet, I am just
happy I did'nt end up with an expensive paperweight.

Specs as follows:
V5 IO
Win98se
AMD K6III+ 450mhz
TennMax Fan
128mb Ram
Second USB Port

I am at 100mhz Bus using K6clkw.exe to crank up the Clock speed (5.5) I had previously
installed the BadFlash approved "L" Shaped copper strip, and Cooling resistor, that was
removed to make way for the PT6702.

HEED Glitch's Warning !!! Don't leave it plugged in, and powered off... Till someone
someone finds a way to turn of the Vcore. (see above Posts).

All-in-All a Great Hack !!!

Thanks for all the help, and special thanks to Rob.... U-the-Man.

I will post pics as soon as I have them....


JohnQ

04-10-2001 23:38:21

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) therealdj
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I have ordered my K62+450 from software and stuff, and my sample PT6702 should be here tomorrow, so I am looking forward to doing some mods over easter.
It shouldn't be that hard to turn off the PT6702 when the I/O vcore is off, if we can figure out how vcore switches off. I don't have my I/O open right now, so I can't check anything. Can someone check if the gate of Q16 (driven by pin1 of U16) goes low when the I/O is off? I suspect this is how it is turned off.
If so we should be able to tie pin1 of U16 to the standby input of the PT6702 with a Schottky diode. The PT6702 spec sheet says if you use a BAT54 or similar Schottky diode in series (anode side to the PT6702) you can drive the standby input with a bidirectional output (like U16).
This could be done with either an axial lead diode from pin1 of U16 to pin8 of the PT6702, or perhaps R204 could be replaced with a SMT diode, and a jumper from the gate pad of Q16 to the PT6702 stby input (pin8). In either case the inputs to U16 should be set for an output of 3.5V so that the stby input is at 3.5V when it is on.

I'll try this when I open my I/O, but wanted to suggest it in case someone gets a chance to try it before I do.

Good Luck,
DJ

04-11-2001 13:00:26

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Glitch
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therealdj: I've already tried that (that was the first thing I tried). The pin goes to zero volts but does not sink any current.
Glitch
Electronics run on smoke, if you let the smoke out they won't work
04-11-2001 19:12:43

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Enduser6
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Installed the PT6702, works great! Running AMD K6-2 450 - did not do any overclocking yet. I been trying to figure out how to shut down vcore when IO is powered off but unsuccessful. The only thing that will shut it down is a ground to Pin 8 of the PT6702 (its open so its always on). I might have to resort to a manual toggle switch for now. Overall its a great mod (btw its free). Thank you all!
04-14-2001 09:32:15

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Enduser6
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Did my testing over weekend with a AMD K6-2 450Mhz (over clock to 550Mhz via k6clk). My CPU temp and IO temp is under 100F with the shield and cover on. I am using SMC 2202 USB ethernet, its also stable with the local and dsl network. I transfer a large file between server, play MP3 etc...no disconnect (I did have disconnect when I was using SMC 2102 version)...Only *two* issue I have is of course the core voltage always on with out unplugging the power brick and the other thing is I could not get my IO to power up (after I turn it off) using the front panel power switch unless I disconnect the power brick, wait a few seconds, re-plug then the power button works again.
04-15-2001 17:09:22

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) brian
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OK I'm interested in a CPU upgrade now that there is a switching regulator out there. My question is:

What is the power dissipation of an original 200MHz winchip? I've found specs on the K6III 475+ at 16W power. and a K6III 450 at 20W. I don't have the spec on the K6III 450+ or the winchip. I'm looking to compare due to heat limitations within my case. I currently don't have a CPU fan on my IO. I have all internal: HDD, ethernet, Audio MODS (custom), and serial mods. I have an almost stock heatsink and I want to keep it that way. I need to keep my internal power dissipation at or below it's current level if performing this mod...

To those who already performed this mod: What are you doing for the input and output capacitors on the voltage regulator? Where are you puchasing them from? Do you use them at all? Are they needed at all due to the capacitance provided onboard near the CPU?

Brian

04-15-2001 21:07:02

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Glitch
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Hurray! I think that I am finally done with done with my DC-DC regulator mod. I ended up connecting pin #8 to the "third" lead of the Q16 via a schottkey diode. I tried this before and is didn't work. This time it worked. I'm not sure why it didn't work before, but I'm not going to worry about it now . The diode is necessary because the voltage on the "third" lead goes to 14v+ when the power is on. I'm not exactly sure why this happens (yet). I put up a few pictures of my installation here and mirrored here. Everything powers on and off properly now.

FYI, I had a capacitor on the regulator output but I removed it. It seemd to work fine without it. I still need to go back with a scope and quantitatively see if it makes a difference.


Glitch
Electronics run on smoke, if you let the smoke out they won't work
04-17-2001 18:53:29

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Enduser6
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Glitch: This is great news! Thanks! Now which one is the "third" - is this one closest to the CPU or SODIMM? If I measure it to ground it will be +14 volts when power on and ground when off. I am not familiar with a schottkey diode (or any diode) - is this readily avialable at RS?
04-17-2001 22:28:01

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Glitch
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What I'm calling the third pin of Q16 is the device's gate. The gate connects back to U16 pin 1 via R204. Its easier to describe by process of elimination. The drain is connected to the 3.5v supply (big tab/center lead). The source connects to the Vcore (to the big SMC capacitors). The gate is the one that is left over.

FYI, I totally removed Q16 to do the modification. This gives a convenient place to solder the wires from the PT6702. It also ensures that Q16 and the PT6702 aren't active simultaneously. I'm guessing that you'll see smoke if they are both working at the same time .

BTW, the voltage of the gate goes nuts (14v+) due to the feedback loop to pin 2 of U16. There may be a way to "rewire" the op-amp to keep this from happening (maybe remove R203?). I probably won't bother with this ("don't fix it if it ain't broke").


Glitch
Electronics run on smoke, if you let the smoke out they won't work
04-18-2001 06:23:57

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Glitch
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Enduser6: I forgot... A schottkey diode has the characteristic that the forward bias voltage drop is usually lower than a regular diode (.15v vs. .7v). This allows pin 8 to be pulled below the 1.0v necessary to turn off the PT6702. On my machine the Q16 gate is at about .5v with the CPU installed, the power off and pin8 connected. With a schottkey diode the voltage at pin 8 is about .65v (.5v+.15v). With a regular diode the voltage would be at 1.2v (.5v+.7v) and the PT6702 wouldn't turn off. Your machine may behave differently. YMMV.
Glitch
Electronics run on smoke, if you let the smoke out they won't work
04-18-2001 06:32:29

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) therealdj
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Glitch,
I'm still in the process of modifying mine, so I haven't been able to test anything yet. (These darn household projects always seems to come up when I'm in the middle of a fun project like this processor upgrade!!)

The output of U16 goes to +14V (+18V on mine) because the "rail" or VCC+ of the opamp is 18V, and pin2 is below pin3. For a Vcore of 3.5 V this fully turns on Q16 so it acts as a switch.

You may be able to lover the voltage on pin8 of the PT6702 by removing R204, depending on what value it is. It is currently in series with your schottky. I was planning to replace R204 with a SMT schottky and tie pin8 of the PT6702 to the gate pad of Q16. This would connect the schottky directly between U16 pin1 and the PT6702 pin8.

I agree that you should not need additional capacitance on the output of the PT6702, since there already is 1000uf on the board.

Enduser6:
The 1N5711TR and 1N6263TR at radio Shack are small signal schottky diodes, listed on their web page. You could try one of them. I would take a look at all of the diodes on display at RS, and pick out one with the lowest forward voltage (Vf). You only need a very small diode (it only has to carry .01ma, or .00001A, according to the PT6702 data sheet) so current rating should not be a concern. Don't be too concerned if the Vf states .7V or 1V, because that is worst case at rated current, and it will be much lower at low current. You can use a surface mount or axial lead, depending on which you are more comfortable with soldering.

04-18-2001 11:40:14

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) therealdj
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Enduser6,
I should have said look at all of the SCHOTTKY diodes at RS in my previous message. I assume the packages are labeled if they are schottky.
04-18-2001 14:12:33

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Enduser6
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Thanks guys for the replies about the diode. I did some voltage checks today. I am getting 18V on the gate when power is ON (CPU installed and IO running) and once I turn it off I get 0V, also I get 0V on the Drain and Source (yes everything is OFF). Now check this out: If I unplug the power brick and wait a few seconds and plug it back in the Drain is at 3.3V and Source 2.2V and gate is 0v and I can turn on the IO via front power switch. Really strange but the IO is running great. The only major problem I got is once I shut down windows and it powers off....I cannot turn it back on unless I remove the power brick. I will just try the SCHOTTKY diode and see what happen.

PS: I completely removed Q16 and I have only the PT DC-DC regulator in place of it.

04-18-2001 22:01:00

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Glitch
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therealdj: Good idea! I like the idea of replacing the resistor so the diode won't be "hanging off" the PT6702. FYI, I think that R204 is only 10 ohms.

Thanks for the explanation of the what is happening with the opamp. I figured it was some sort of "unstable" condition that drove the output to a limit. It has been about 20 years since I have done anything with opamps. Sometimes it seems like I have forgotten more about engineering than I remember .


Glitch
Electronics run on smoke, if you let the smoke out they won't work
04-19-2001 06:46:32

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) therealdj
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Glitch:
It was a good idea until I talked to one of our EEs here and found out that they probably don't make a diode in that small of a package. The die size of a diode, and the fact that it has to be sealed in a package probably means that they don't make them in a package smaller than a SOT23. I might try a SOT23, or just an axial lead diode, depending on what I can find.
04-19-2001 10:23:33

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) mp3boombox
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Welp this pisses me off to no end!!!!! I should have had my dc-dc already but dont, well gues what. They never sent the dam thing, aparently it was over looked or something what ever the reason is/was its NOW in the mail luckly!

I await to see what you guys have come up with on the power 0V at power off on cpu fix ends up being? I wont recive my dc-dc till mon.

Also someone realy needs to make a step by step install instruction post!

the a-z with the 1-2-3 foot notes on each step. i.e. which side of the dc-dc is pin1-x
what goes to what what gets what, and also some info on that diod you guys are talking about. or STEPs of.

thanks chow

04-19-2001 14:20:12

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Enduser6
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therealdj & Glitch: Looks promising! RS dont have a schottky diodes at their stores, I have to order online for .35 with $2.50 s/h. I hook up regular diode laying around just for tests. You guys are right about the voltage drop on powering down the IO, its still above 1v (.5 + .707) at Pin 8. But what I am getting looks promising, I regain control of the front power on and off switch & the Vcore is Ov!! The only thing thats on all the time is the Vin 3.3 on the large pad, the source goes to 0v!! hip! hip! hurrah! Anyway, just to make sure I will get a schotty diode, to make sure it Vout stays off. Thanks guys.

My hook up was like this: PT6207 Pin 8 ---anode/cathode---Gate

Anybody got a spare SCHOTTKY diode?

04-20-2001 00:05:41

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Enduser6
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mp3boombox: Here is a *MY* rough step by step, it just might help.
I got a V1 IO

First set up the PT6702:
1.) Pin 2 --- 10K resistor--- Pin 10
2.) short Pin 7 to Pin 13
3.) Hook up a 4 pin dip sw to pin 3, pin 4, pin 5 and pin 6 (the other side of the dip switch connect all to pin 7 (ground)
4.) short Pin 23 to Pin 22

The PT6702 is ready to be hook up to the IO but let lable things first:
Pins 10,11,13 are shorted together if you look closely on the PT6702 (Vin)
Pins 21,22,23 are shorted together if you look closely on the PT6702 (Vout)
Pins 13,14,15,15 are shorted together if you look closely on the PT6702 (Ground)

Prepare the IO.
Remove Q16, the large pad is the Drain, the small pad close to the CPU is the gate and the small pad close to the SODIMM is the source.

Connect the PT6207 to the IO
PT6702 Vin connects to IO Q16 Drain (this is 3.3V)
PT6702 Vout connects to C154 and C155 (ends of the caps closes to the CPU - Source)
PT6702 Ground connects to IO ground (its up to you where)

Set your Vcore (Vout/Source) voltage via dip switch
2.0V Vcore = PT6207 Pins 3,5,6 to ground
Any other voltage see the Programming Table

Check Vcore Voltage
With CPU out, Power up and you should have 2.0 volts at the IO Source pad or at the C154/C155 or at R60/R61 (pads closes to the edge of the motherboard)

Connect the AMD K6/2+ (Vcore 2.0), Set up clock speed to 100Mhz and multiplier to 3X and boot up, use k6clk to change to clock multiplier to 5x for 500MHZ

Setting up the Standby Pin 8 (to turn off Vcore automatically)
Q16 gate --- anode/cathode --- Pin 8 of PT6702 (schottky diode)

Check Vcore to be at 0V when IO is Power down (brick still plug in)

Thanks for all the guys who help me out along the way, the above is *MY* step by step procedure I performed on my CPU mod, cannot and will not garrantee it works on your IO. Good Luck

04-20-2001 00:43:54

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) therealdj
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enduser6:
Thanks for the step-by-step. I am writing one up as I go along and will post it when I get things working.

I got everything wired up, but mine won't boot yet. I need to do some troubleshooting. My Vcore reads 2.1V with PT6702 pins 4,5,6 grounded. I think I need to add a dip switch, and adjust it closer to 2.0V. (I wish I could put on hold my other projects at home so I could spend more than 15min a day on this project!!!)

Did everyone place a resistor and cap across the reset switch? If anyone has details for this please let me know. I saw some mention of it, but haven't found any details yet.

You are right about making sure that the PT6702 stays off. You don't want a marginal situation where it could turn on under certain conditions, and then fry your processor without you knowing. My U16 measures .67V at pin1 with the schottky and PT6702 connected, and .7x at pin8 of the PT6702.

enduser6:
If you still need a schottky I could mail you one. Send me your snail mail address at
therealdj at netscape dot net

04-21-2001 07:44:38

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Enduser6
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therealdj:
Opps. Dip should be 4,5,6 to ground for 2.0V, you are right. Thanks for the offer on the diode but I finally order it via RS for $2.70 s/h (.35cents diode). As far as the cap and resistor on the reset switch, for my mod - did not add any. Just the usual moving the R60/61 resistors to create that voltage diveder network in the IO (original mod with the cooling resistor) and removing Q16.
04-21-2001 14:14:12

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) mp3boombox
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DIDO thanks for the post now just waiting for the darn part.

also is there a way to easly rig up the formor hack setup i had for the 500k pot to change the voltage?? I'd like to run the voltage around 1.8v

also this is a bios controled automatic mother board if posable someone whocan do bios working syhould look into seeing if a menu for editing the the POWER tothe mother board can be changed. the USB support is being droped by one of 2 things. its eather going to fast (i dont believe in this one), OR the chip is getting to hot which controls the USB ports and needs cooling. OR the power to the mother board is to weak, and needs to be bosted up a few points of a volt.

i believe in the second or 3rd idears. reason being is you can clock the fsb to 124mhz not to mention this same chipset is used in some 133mhz FSB BOARDS.

so i think its a power problem.
if any one could shead some light on this please do.

04-21-2001 19:24:55

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) mp3boombox
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come to think of it IT could be a driver problem also not being able to handle the higher speeds, TIMING???
04-21-2001 19:30:44

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Programmer
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when you overclock the FSB you are increasing the PCI bus speed as well, as the only devices on the PCI bus are integrated into the chipset, and the chipset is capable of dealing with it this is not generally a problem.. The comment about these chips being used in 133Mhz mhz systems is why I am writing.. When the chip is used in a 133Mhz system, the PCI bus is 1/4 of the system bus or 33Mhz. This is the exact same speed as it is when used in a 100Mhz system 1/3 of 100Mhz. when you under/overclock your FSB (set it to a setting not divisible by 33Mhz) then the PCI frequency goes out of spec and you risk screwing things up. A driver will never set the timing right on this chipset, the timing is determined by the chip itself, and provides no method for correction. After you get your stepdown, try changing your FSB to 100Mhz, and following the steps posted elsewhere on the board to see if that solves your USB problem.
04-23-2001 06:08:08

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) therealdj
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mp3boombox:
The PT6702 is voltage selectable for 1.30V to 2.05V, just by jumpering pins 3,4,5,6. For 1.8V jumper pins 4 & 6 to ground, and leave 3 & 5 open. This is in the data sheet on their web site. I recommend getting the sheet, because it has a lot of good information.

I still can't get my system to boot. I tried the K62+450 processor in my Abit TX5 motherboard, and it works, so it is OK. I tried switching the FSB to both 66 & 100. I tried re-seating the bios chip, and even replaced the bios socket, with no luck.

Here is what I have done so far ( I believe I have a V2 I/O):

Boot up to CMOS setup (CNTRL-ALT-ESC) and select CHIPSET FEATURES SETUP
SET bank X/X Dram timing to 8 ns
SET SDRAM cycle length to 2
Save & exit

Move SW3 to SW1 to set the multiplier, and remove R130 (0 ohm)

Solder jumpers onto R329 & R330 pads for 100Mhz bus (I used R130 for one of them)

Here I booted with the Winchip and verified that the system works at 100Mhz FSB

Enable split voltages by moving R60/R61 to R184/R185

Clip all the pins on the PT6702 (pins 1-23)

Solder a dip switch to pins 3,4,5,6 and the other side to pin 13(data sheet says use pin 13, not pins 14-18 as voltage programming ground) Set the switches for 2.00V (It read 2.1V, so I adjusted it to 1.95V with no luck)

Solder a wire from pin7 to pin13 of PT6702

I did not connect a pull-up to pin2, Power Good, since this is not required if this signal is not used

Remove Q16

Connect three 22 AWG wires, one to pins 10,11,12(Vin) one to pins 14,15,16,17,18(GND) and one to pins 19,20,21,22,23(Vout)

Connect the wire Vin (pins 10,11,12) to the Big square pad of Q16

Connect the wire Gnd (pins 14,15,16,17,18) to Gnd, I used the big square pad with the mounting screw in it, to the left of C154

Connect the wire Vout (pins 21,22,23) to the next biggest pad of Q16

Connect a schottky diode from pin8 of PT6702(anode) to the smallest pad of Q16(cathode)

Solder a .010 ohm (closest value I could find) smt 1 watt resistor in parallel to R302 (to get a higher current limit.)

WITH THE CPU SOCKET EMPTY, test your Vcore by powering up and measuring from GND to the Vcore pads of the now-empty R60/61, and voltage at pin 3 of Q16, and check that it goes off when the power is off (with the power supply connected)

(Thanks to badflash, rnunes, Tinman2, and others who I plagarized much of this from.)

Does anyone have any suggestions?
Has anyone "reversed" this mod? I wonder how much I have to undo to go back and try the Winchip.
Can I just disconnect the PT6702 and short the drain and source pads of Q16 to supply Vcore to the Winchip? I don't understand EXACTLY what moving R60/61 to R184/185 does.

I greatly appreciate any suggestions.

Thanks

04-23-2001 07:29:33

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) therealdj
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BTW: I have a version 3 with i-opener_bios_old.bin
flashed into the bios. I believe this is the original bios version. Do I need a bios upgrade?
04-23-2001 08:47:04

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Tinman2
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therealdj:

Be sure to check the seating of your sodimm memory, I had pulled my hair out for almost a week trying to get one of my IO's to boot, and hadn't even messed with the memory except for maybe some unknowing pressures applied to it while working on other things. Try removing it and replace it to re-seat it, or even press down on the top of the sodimm as your trying to boot. I hope this helps.

Good luck to you,

Tinman

04-23-2001 14:27:38

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Enduser6
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therealdj: By any chance you got a SODIMM PNY 128 from Best Buy? If so, you might what to check the BBS General Section. I have the same problem, power up, HD spin, and fan spin but nothing. Reseat everything but nothing (1% at a time it actually work, when the moon is full and properly align to Mars), it was the memory - I swap the memory to another IO and the problem traveled. Just a thought.

BTW, my scotty diode arrived and it worked great! Good Luck.

04-23-2001 15:48:45

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) mp3boombox
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OK got my dc-dc working first try, BUT I'm going to write up an intall HOW TO and post it because if you look closly almost every post has a numarical error which can throw people off!

I'll write up a 1-2-3 with reason's behind things. so far every post has left a lot of blanks.

04-23-2001 20:16:17

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) therealdj
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Tinman,
Thanks for the reseat on the SODIMM suggestion. I tried it, but it did not help. I also replaced the flash bios with another chip I programmed here at work, but that didn't help either. I only had about 10 min. to work on it last night, so I didn't get very far.

enduder6,
I have a 64M PNY SODIMM from Best Buy that I have been using for months. Thanks for the heads up though.

I think I am going to try putting the Winchip back in and see what happens.

Thanks for your help.

04-24-2001 06:37:23

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) rnunes
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Here are some pictures of my DC-DC Hacks. The first picture uses the power trends. The next two show the Datel DC-DC converter. Looks like I can get away with the passive heatsink. This one is using a K6-2 @ 450 Mhz (100 Mhz FSB), CPU Cool temps are 24, 38 and 38 degrees. The datel has rubber feet on the bottom to keep it off the PCB and wedges firmly once the heatsink is screwed down.

Rnunes

04-24-2001 19:03:36

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Glitch
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rnunes: Very nice! Can the Datel converter be switched off like the PowerTrends one? It certainly looks like it packages much better.

BTW, if the other pictures are of your family, congratulations! Looks like you will have a bunch of sleepness nights in the near future <g>.


Glitch
Electronics run on smoke, if you let the smoke out they won't work
04-24-2001 19:34:06

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) mp3boombox
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I got a question??? if you leave the power pluged in and you run the IO then turn it off but leave the Power pluged in?? waht is it that happends????

case i did this the other day for almost 4 hours, came back and turnd on my iopner just fine. I notted my error when i turnd on my io cause it turnd ON.

but there was NO heat or any thing going up??? or hot ANYWHERS, the power cube was even COOL. and i dont have the diod installed either??? now i do still have the old V3 hack in place even with teh resister could this have any thing to do with it????

cause from waht i had read befor the computer got VERY HOT if you leave it running pluged in but not turnd ON to have the fan running????

no DIOD but stone cold to the tuch???

04-28-2001 08:41:09

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Glitch
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mp3boombox: Check to see what happens to the 3.5v supply when you turn off the i-Opener. Maybe on a v3+ the 3.5v supply gets shut down. I have the PT6702 installed in a v2. The 3.5v supply is always active in my machine. I also have a Lasagna heatsink which is useless without the fan running. A stock heatsink may be able to disappate the heat well enough to keep things cool even if vcore doesn't get shut down.
Glitch
Electronics run on smoke, if you let the smoke out they won't work
04-28-2001 09:14:03

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) mp3boombox
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I'v got a v3, I'll check the next time I take the thing apart. to see if it it is dropping the voltage. I think it is. Oh speaking of would this hack make a v1 k6+ ready??? i know they where having problems befor due to power problems and the v1 missing some parts. It would be nice to upgrade a v1 of mine to a k6-2 500 for next to nothing.
04-29-2001 08:24:20

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) mp3boombox
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Ok just checked :) I'v got a v3 v3b i think?? cant rember but in any case I dont know if it has to do with the orignal dropping resister hack BUT i dont need the DIOD. the only thing left inplace from my orignal hack are the 500k pot and the resisters i had put in place by the q16 therm. sensor.

BUT i'm just barly below the voltage dropping line. the only heat I am getting is a LITTLE bit of HEAT FROM THE standerd IO power supply which is almost less then noticeable.

HAS any one else put a dc-dc into a v3??? this will be intresting to see if its because of the orignal q16 dropping resister mod or just v3's in general.

04-29-2001 08:31:42

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Glitch
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mp3boombox: Yes, this mod would be perfect for a V1/V2 K6 machine. All you have to do is install the DC-DC converter and do the split voltage mod (move R60 & R61 to R184 & R185). I also did the SW1/SW2 dip switch mods.

BTW, the diode is there to keep from backfeeding current into pin8 of the PT6702. I forget the max voltage spec for the pin, but the op-amp rail of 18v is well above it.


Glitch
Electronics run on smoke, if you let the smoke out they won't work
04-29-2001 12:10:20

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) parasyght
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Its been about a week and i havent heard from powertrends about the sample pt6702. The only thing i did was fill out the request form. Is there anywhere that has these for a reasonable price? I was also wondering if therealdj ever got his to work right. How about the datel converters? no one posted any information about how to hook that one up. The datel seemed to be a little more expensive than the pt6702.

mp3boombox:
did you ever finish your write up on the install of the pt6702? Enduser6 seemed to have written a nice 1,2,3 plan. You mentioned that they all had numerical errors, what did enduser6 post that was wrong, so i dont break this thing if i ever get it.

05-09-2001 22:48:30

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) r_fl_z
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Parasyght:

I received my PT7602 5 days after requesting it. Try again, it may have gone walkabout.

05-10-2001 10:11:34

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) parasyght
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i got a reply from a lady stating that she sent it off to me. Now how do i go about getting two more? Can i buy the pt6702 from them? I feel kinda bad just getting one for free when i know that i only need a few, when they expect to sell them by the 100's.

Since this mod has proven to work wonders, mp3boombox should finish his write up and post it on the bbs with a new title.

05-10-2001 16:14:31

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) mp3boombox
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2 more will cost you money :),

as for the write up on the install. I have it done but i need to refine it. I'll post it some time soon. Been realy busy latly, hence i have not put any post's up latly.

Right now I'm off to RS to order a schottky or bat54 DIODE for my iopener's dc-dc. Just to be on the safe side of things.

Then its back out to fuss with the dang lawn mower which will not kick over. I realy hate fixing them!! nothing but a greesy grassy mess.

Also my write up is VERY basic 1 2 3 on the dc-dc, and you wont have to do any searching for info which is iffy on the install. :) i check these things with my roomate whom is not very technical with electronics. If he can follow the HOW-TO I'm happy hehe.

05-12-2001 12:53:04

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) Enduser6
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Got one spare PT7602 (new), was going to put it in my second IO but willing to part with it in exchange for a websurfer keyboard or webplayer keyboard, just trying my luck here. Being looking for one for months, willing to buy it too! Anyway, drop me a note: enduser6@juno.com
05-13-2001 17:27:57

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) parasyght
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MP3boombox: your roommate must have failed the install. That would be great if you could post the writeup. This pt6702 should be more popular than it is. My k6's with the the dropping resistor still would heat up way to much, in fact i dont think the resistor did anything but a 1 or 2 degrees. People need to know about this, so get your writeup out there man. You should include the stuff about the shottky diod too, that sounds critical to this mods success.
05-17-2001 15:32:53

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) mp3boombox
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I'll post it on saterday some time.

I'm just poping on VERY QUICKLY!!!! SARRY TO keep you people waiting. I just have no free time.

fri. I'm working a double 6am-11pm 2 jobs UGH!!!! its all in the name of MONEY and that GEFORCE3 mega video card!!! with my name on it.

as for the dropping resister hehe TRUST ME if your system runs stable at OVER 300mhz and you got a good cooling system on the q16 CHIP!! trust me the dropping resisters are doing there job.

AS for the diod on the dc-dc as someone mentiond befor its to protect the dc-dc supply from harm of backflow. Though i believe that part of the problem this fixes is DUE to the version of the iopeners. I'v got a v3 and the diod is not installed YET!! But, nothing gets hot when the power supply is pluged in and system is turnd off??

The people who have had this problem all installed the mod on V1'S or v4+??? i cant rember.

05-17-2001 20:46:24

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) therealdj
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Here is the procedure I used to upgrade mine.

I had problems getting it to boot initially, but it turned out to be a combination of having the SODIMM seated, the BIOS chip seated, and the correct CPU multiplier all at the same time. Once I got those things straightened out it works great.


Boot up to CMOS setup (CNTRL-ALT-ESC) and select CHIPSET FEATURES SETUP
SET bank X/X Dram timing to 8 ns
SET SDRAM cycle length to 2
Save & exit

Move SW3 to SW1 to set the multiplier, and remove R130 (0 ohm) and set the multiplier to 2.0 for the Winchip

Solder jumpers onto R329 & R330 pads for 100Mhz FSB (I used R130 for one of them)

Here I booted with the Winchip and verified that the system works at 100Mhz FSB

Enable split voltages by moving R60/R61 to R184/R185

Clip all the pins on the PT6702 (pins 1-23)

Solder a dip switch to pins 3,4,5,6 and the other side to pin 13(data sheet says use pin 13, not pins 14-18 as voltage programming ground) Set the switches for 2.00V per the spec sheet (pin3 open, pin 4,5,6 closed)

Solder a wire from pin7 to pin13 of PT6702

I did not connect a pull-up to pin2, Power Good, since this is not required if this signal is not used

Remove Q16


Connect three 22 AWG wires, one to pins 10,11,12(Vin) one to pins 14,15,16,17,18(GND) and one to pins 19,20,21,22,23(Vout)

I mounted the PT6702 along the edge of the case on the processor side, below the speaker. I placed one of the legs under the speaker clamp, and tied it to the clamp with a tie-wrap. I glued the other end down with some RTV glue.

Connect the wire from Vin (pins 10,11,12) to the Big square pad of Q16

Connect the wire from Gnd (pins 14,15,16,17,18) to Gnd, I used the big square pad with the mounting screw in it,
to the left of C154

Connect the wire Vout (pins 21,22,23) to the next biggest pad of Q16
(I didn't add any additional capacitors, since there is already 1000mfd on the IO.)

Connect a schottky diode from pin8 of PT6702(anode) to the smallest pad of Q16(cathode)

Solder a .010 ohm smt 1 watt resistor in parallel to R302 (to get a higher current limit if necessary, for clocks higher than 3 x 66 (default).)

WITH THE CPU SOCKET EMPTY, test your Vcore by powering up and measuring from GND to the Vcore pads of the now-empty R60/61, and voltage at pin 3 of Q16, and check that it goes off when the power is off (with the power supply connected)

Set the SW1 multiplier to 3.0 (these things don't seem to boot higher than 300Mhz)

Install the K6 processor (make sure you have a heatsink & fan if you are going to leave it running for more than a few seconds)

Let 'er rip!!!

I used
k6clk.exe 4.5
to jump from 300 to 450 Mhz in the autoexec.bat

I have some pictures to post, but haven't downloaded them to my PC yet. I'll try to do that this weekend.

Thanks to badflash, rnunes, Tinman2, and others who I plagarized much of this from.

05-18-2001 11:56:45

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) parasyght
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right on man, the write up looks good. It will be even better when you post some pictures to clarify. You forgot to mention what version you modded. How would this apply to a v1? Would there be any changes in the steps?
05-18-2001 17:06:13

New MessageRE:DC-DC Stepdown regulator for CPU MOD (modified 0 times) therealdj
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Well I finally downloaded the pictures from my digital camcorder last night so here they are:
http://y42.photos.yahoo.com/bc/therealdj2/lst?.dir=/My+Photos&.src=ph&.last=1

There are several pictures of my PT6702 mounting and electrical connections. It is mounted along the side of the case below the speaker. I put one leg under the speaker bracket with a tie-wrap to hold it (the tie-wrap is hard to see in the picture), and I put some RTV on the other end.

There is also a close-up of the connections from the PT6702 to the Q16 pads and ground. You can see the schottky diode is soldered directly to one of the pads, with some RTV to help hold it in place. There is an orange wire from the other end to the PT6702. The other wires are all blue. One of them is hard to see because it is under the diode & is covered with RTV.

I also came up with a new circuit for controlling a 12V processor fan. The schematic is posted at the address above. The circle with an M is the fan motor.
It is a NPN transistor used as a dropping element with a pot to control the voltage. The pot controls the voltage at the base, and the emitter is connected to the fan. The emitter follower configuration means the voltage to the fan will be about .5V to 1V less than the base, depending on the transistor you use. I use the output from U16 pin 1 to supply the voltage to the pot and to switch it on and off (see restriction below). The pot can be adjusted to control the voltage to the fan, and can be set to anything from 0V to about 16V. The collector is connected to the 18V supply at one of the caps on the motherboard. This can be seen in the "fan regulator voltage adjust pot" picture. It is the orange wire which goes to the upper left side of the picture.

Restriction: This will only work with a DC-DC regulator configuration like the PT6702 (or if you have vcore=vio) since, if you use U16 to regulate the voltage to Vcore, the output on U16 pin1 will not be at 18V when the processor is turned on. (If you are not sure if you can use this circuit, measure U16 pin1 and make sure it is at <1V when the IO is off and at 16-18V when it is on.)
I mounted the transistor under the speaker bracket. I bent the bracket a little to clamp it tighter, and used some RTV to help hold it in place. The transistor will get warm, but should not get too hot. It should dissipate about a half of a watt ((18V - 12V) * 80ma). I don't know what the part number was of the transistor I used (I think it was an OEM marking). Mine is an overmolded d-pak, but a TO220 should work even better. Use a NPN transistor which has a collector current (Ic) greater than the current required by your fan (mine is 70ma @12V), and a Vce >20V. The 2N6292($1.29) or TIP31($.99) or many others at Radio shack should work fine.

I glued the pot to the circuit board under the SODIMM door, so I can adjust it if necessary. I used the ground pad next to the SODIMM socket for the pot ground and the minus side of the fan. Be careful to solder the wires to the edges of this pad since the RF shield has a standoff which sits on this pad. The pictures I posted should help you see how I mounted everything.

A word of warning when using silicon RTV. Silicon will prevent solder joints from wetting properly, so be careful where and how much you apply.

As you can see from some of the pictures, I am using a stock heatsink (milled out for a hard drive mount.) I have cut a hole in the back of the case and RF shield for the fan and to allow air flow. Running at 450 Mhz with a K6-2+ 450 with Vcore at 2.0V and Win98se idling I get about 120 F at the motherboard and 110 F at the processor as reported by MBprobe.

parasyght,
Mine is a Version 3, and as far as I know there should not be any changes for a version1, but I am no expert on IO versions.

05-24-2001 14:19:20

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