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Home / I-Opener Areas / I-Opener Technical Stuff No Power At All! Is there a fuse somewhere?

No Power At All! (modified 0 times) Las_Vegas Profile | Email Last night my iopener was working fine. I shut down normally. No problems. This morning I went to power it up and nothing! NOTHING! The power LED didn't light up. The hard drive didn't spin up. Nothing. I immediately checked the power supply. The green light glowed nicely. I check the power from it. All okay. I took the iopener apart. Removed the hard drive and the modem. Tried again. Still nothing! Okay... Took the meter to the iopener. I have 19v at the ferrite core. I have 19v before and after Q34. Voltage shows okay through the discrete components below Q34. Nothing anywhere to the right of Q34 though. Does anyone have any ideas (Other than selling it in eBay!)? Thanks, Las_Vegas http://iopener.how.to/ 08-24-2000 12:08:36

RE:No Power At All! (modified 0 times) Las_Vegas Profile | Email Okay. I jumped the gun a bit... Looking back at the board. I do have the 19v pick up again on the right of the power supply circuit. Everything seems to measure fine until I get to L32 and L39. L32 has about 3.5v going into it and L39 has nothing. Following the 19V on the right. There are a series of 330ohm resisters in series to the right of SW3. The pads are marked as diodes (D13 and D14) but the look like resisters (marked 331) and actually measure about 300ohms both ways. After D14 there is an additional one jumpered between D14 and a capacitor (number obscured by the additional resistor). Power measurements at these resisors are 19v going into D13, 12.75v between D13 and D14, 6.36v at the juncture of D14 and the added component and Zero volts at the juncture of the added component and the capacitor. Perhaps this circuit is being used to tap the various voltages for the system? Hmmm... 08-24-2000 12:38:47

RE:No Power At All! (modified 0 times) Las_Vegas Profile | Email Okay... I've been running around in circles on this one. Please! If you have any experience with power supplies at least let me know you're reading this! I'm a computer tech. I've never dealt with power supplies. I feel like I'm just talking to myself here. I downloaded and studied the data sheet on the MAX1631 that the iopener uses. As I gather it, the circuit has pin 23 (-SHDN) bypassed to GND through a Capacitor and pulled up to the 19v through a 10ohm resister (sheet specifies 220k, but who understands engineers...). This means the chip it configured for automatic startup (DUH!). Okay. Pins 15 (SEQ) and 9 (REF) are tied together indicating that power is controlled by both pins 7 (ON5) and 28 (ON3). Pin 28 measures 5v and pin 7, low. This should mean that 5v is on and 3.3v is off. Here's the clincher. Pin 15 and 9 should measure 2.5v (Measured from the top of C257) at all times. I read exactly 2.5v until the power button is pressed. Then it rapidly drops to about 0.2v Do I have a bad chip? Could there be something else pulling the REF down? Please! I need feedback! 08-24-2000 23:02:31

RE:No Power At All! (modified 0 times) Las_Vegas Profile | Email One more addition to the thread. Still hoping for some feedback. Carefully checking out all the power circuitry, it appears that the 3.5v supply is always on, and the 5v supply is switched using the 3.5v (pin 7 to pin 6 of the front panel board). when the iopener is plugged in, the 3.5v supply turns on correctly. Unfortunately, my multimeter is digital and I can't be sure, it appears that when the power on button is pressed, I get voltage from the +5v supply for just a moment and then everything goes dead (including the 3.5v supply and the chip's 2.5v reference). Monitoring the 2.5v REF, it goes from 0.02v to about 0.4 about 2 seconds after the power is removed. Reconnecting the power brings it right back to 2.5v My guess is that somthing is causing the chip's OVP (Over Voltage Protection) circuitry to kick in as soon as the 5v supply turns on. I tried it even with the WinChip, memory, modem and LCD removed. I even removed my USB hack! Still no +5v... Any ideas? 08-25-2000 00:46:28

RE:No Power At All! (modified 0 times) Turbo3 Profile Removing the cpu and other parts is what I would have suggested but you tried that. Yes it seems like the OVP has cut in for some reason. I see the same thing when I set too high of an operating frequency and/or core voltage. It is a little late now but in the morning I will reread all your posts and check with my iopener power supply. But it does seem like some part (a cap or transistor) has died on you. 08-25-2000 02:34:37

RE:No Power At All! (modified 0 times) Turbo3 Profile Actually I should have said the OCP (over current protection) is probably being activated. Yes the 3.5 volt supply is always on and the 5 is off before you press the power button. You might try isolating the 5v from the iopener by removing R306 the 0.020 current sense resistor. That way you can tell if it is the power supply or the load that is at fault. To remove the large resistor I use solder wick to remove as much solder from both ends. Then with two soldering irons I heat both ends and slide or lift the resistor. There is a lot of copper foil around it so it will take some time to heat it all up. Measuring the voltage drop across R306 I see from 17 to 47 millivolts during windows startup. It mostly sits around 20mv with peaks as the drive runs. With all parts out including the keyboard you should see much less. Anywhere close to 80-100mv is going to trip the over current limit. With R306 removed you could also try an external (current limited) 5volt supply. I would try this if it seems the iopener 5v supply is dead. Good luck. 08-25-2000 08:30:13

RE:No Power At All! (modified 0 times) Las_Vegas Profile | Email Thank you Turbo3! I removed R306. Still no go with the 5v even without a load! That eliminates a lot of circuitry! Unfortunately, my Fluke doesn't measure mV, but that problem's mute now that the cause appears to be before R306. Any ideas what to check next? Since the supply is already out of the circuit, I'm thinking of pulling the large electrolitic capacitor behind the coil. This is new territory for me. so I'm very scared to blowing the, likely hardest to replace, MAX1631. 08-25-2000 09:00:00

RE:No Power At All! (modified 0 times) Turbo3 Profile Don't think it is the large capacitor since it is across the +19 supply in parallel with the other cap (C248) near the 3.5 supply. Check D22, Q33, and Q35. What voltage do you have at the junction of those three parts when you power up? Does it go above 5 which would mean Q35 is bad or is it stuck at 0 which might mean Q33 or D22 is bad. Do you have a scope to look at the voltage? 08-25-2000 09:56:13

RE:No Power At All! (modified 0 times) Las_Vegas Profile | Email No scope. Just my Fluke (Digital Multimeter). I pulled D22 only to find the same results. The junction between the Q33 & Q35 (two resister packs?) shows a momentary pulse on the meter and right back to zero. I think you may be right Q33 is the next thing to get pulled. Now... That appears to be a resistor pack perhaps in parallel? If that's the case, I might be able to get away with replacing it with discrete component(s) as opposed to SMD. Am I right? Thanks Turbo3. Your help is greatly appreciated! Las_Vegas http://iopener.how.to/ 08-25-2000 17:01:15

RE:No Power At All! (modified 0 times) Las_Vegas Profile | Email God! Am I red in the face! Those are MOSFETs! Welp, it looks like Q33 might be stuck on... or pin 19 of the MAX1631 is stuck. I'm not sure if my iron will work well with those tiny pins though. The other components were relatively easy to pull. I've got a temperature controlled Weller iron and a great solder sucker... Las_Vegas http://iopener.how.to/ 08-25-2000 17:24:46

RE:No Power At All! (modified 0 times) Turbo3 Profile No, No those are MOSFETs Si4800DY by Vishay. Here is a link to the datasheet: http://www.vishay.com/docs/70856.pdf 08-25-2000 17:30:35

RE:No Power At All! (modified 0 times) Turbo3 Profile To remove the MOSFETs you need shim stock about the 1/4" wide. Mine comes in a small reel. You make a diagonal cut in the end of a 1" piece and put it in an xacto knife handle instead of the blade. Use soldier wick or your soldier sucker to remove as much soldier from all the pads. Now heat one pad and slide the tip of the shim stock under the pad then heat the next pad and keep sliding the shim stock under each one. Then do the other side and the part falls off. 08-25-2000 17:38:22

RE:No Power At All! (modified 0 times) Las_Vegas Profile | Email I removed the lower MOSFET (I think Q35). D22 remains off. With the power supply plugged in, pin 4 of the missing MOSFET measured 5v. pin 4 of Q33 measures 1.7 volts (as does the output). I assume this is due to it floating. The 3.5v line holds steady at 3.5v. Pressing the power button has no effect on pin 4 of either the missing Q35 (Remains 5v) or the present Q33 (remains 1.7v). However, the 3.5v supply immediately drops to zero. Both of the 3.5's MOSFET's pin 4s measure zero. Perhaps I'm on the wrong track? Or is the 3.5v supposed to shutdown? Perhaps the MAX1631 just won't operate without the missing MOSFET? 08-26-2000 04:02:36

RE:No Power At All! (modified 0 times) Las_Vegas Profile | Email I tried swapping the MOSFETs to see if the behaviour differs. It does. Everything still goes dead when the power button is pressed, but now both Q5 and Q32 have 5v at pin 4. Tell me if I'm wrong here, but I'm betting that the old Q5 (now Q3) was bad since that 5v line from the MAX1631 wasn't present after pressing the power button before. That tells me that Q5 is now working properly, pulling both supplies to ground when they turn off. Now, is there a clue where I might acquire a couple of these Si4800DYs? 08-26-2000 17:41:10

RE:No Power At All! (modified 0 times) Las_Vegas Profile | Email Don't know how that got past me... All mention of Q5 and Q3 above should have been Q35 and Q33. 08-26-2000 17:54:31

RE:No Power At All! (modified 0 times) Las_Vegas Profile | Email Problem Solved!!! Turns out I've been running around in circles unnecessarily. The absence of the current sense resistor caused an UCP (Under Current Protection) condition in the MAX1631. So anything I did with that resistor removed would produce the same results. The MAX1631 simply shut down. I tried bypassing the io's power supply with another unswitched 5v supply with the drive connected, but no memory and not proccessor. The drive started spinning, but very slow. It never came up to speed! I concluded that the problem likely was somewhere else. I finally found that the board was produced with two traces between line one and two of the second USB port. Just the act of soldering pin one caused it to short slightly (enough!) with the adjacent trace. I had removed the wire but hadn't found the short in the process! This happens to be the very same flaw that caused the Apple /// to fail! Clearing out the short, and rebuilding the power supply returned my +5V supply! Now I reinstalled everything, including the USB mod, but this time I used solder extreamely sparingly and only on the backside of the board. Everything started up properly and I'm back in business. There is one good side to this blunder. I now know more about the MAX1631 then I ever thought I would have! Thank you again, Turbo3, for your suggestions. At least I now know the function of the parts within the power supply... 08-27-2000 06:03:59

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