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Old 05-02-2021, 06:46 AM   #1
N3Star
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Default Abit IC7 black screen

Hi, some time ago I got myself a great retro motherboard - Abit IC7. It used to work... Yeah, used to. I checked it myself, right after it arrived in the mail, booted only with Radeon 9550, which is the newest card I have, GF4 MX400 showed nothing. Right after I moved to the new house I noticed 3 bad caps (marked red), which I replaced with some more or less junky ones thinking bad, but working is still better than good, but faulty. And after that board doesn't show anything. It still tries to live - green and red LEDs are working, fans turn, speaker beeps when there is no RAM or GPU. The weird thing is that without anything connected it beeps that it has no GPU, but diodes on the keyboard initialize, numlock and capslock seem to work, but as soon as GPU is in, keyboard is only initialized, but after that all keyboard diodes are off, numlock and capslock don't trigger diodes, buzzer is silent. Today I replaced these caps with used, but better quality, unfortunately no change. The one thing I noticed that (marked blue) 2 13N03L MOSes are very hot to touch. As with my skill in hot air soldering it would mean pretty much destroying one PCI slot I really don't want to desolder them, so is there anything else I could check before replacing them and hoping that NB isn't shorted?
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Old 05-03-2021, 03:09 AM   #2
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Default Re: Abit IC7 black screen

I took time today and searched my parts bin for replacement MOSFETs and found ones compatible. Of course it couldn't be that easy and this repair did absolutely nothing, board behaves exactly same as before. The one thing I notice is that the board bends like a banana when cooler is attached, so maybe some BGA balls from NB are ripped from PCB.
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Old 05-20-2021, 07:33 PM   #3
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Default Re: Abit IC7 black screen

Hi N3Star,

Try cleaning the AGP slot contacts first, as that can sometimes cause strange issues of video card not working and motherboard freezing. The easiest way to clean the contacts is to take a video card and insert and remove it at least several times. I know you already did that by trying different video cards, but it still might be worthwhile trying.

That aside, do you happen to have a PCI video card?
Since you say the motherboard appears to make the keyboard LEDs flash and NumLock responds without video card, then that suggests it might be booting properly. If you have a PCI video card, you may be able to see if at least the motherboard POSTs properly.

As for the hot MOSFETs... how "hot" are we talking about? And does that happen instantly or when the motherboard has been running for a while?
In either case, measure the voltages on the Drains and Sources of these MOSFETs both when there is a video card and when there isn't one. That might show a clue if the AGP communication voltage is there and at the correct level.

Quote:
Originally Posted by N3Star View Post
The one thing I notice is that the board bends like a banana when cooler is attached, so maybe some BGA balls from NB are ripped from PCB.
It's quite possible if the cooler really warps the board very badly. I've seen it happen before. Unfortunately, Intel's latch mechanism for socket 478 / Pentium 4 is really silly, and depending on the cooler manufacturers, some coolers will really warp the motherboard, while others won't as much. But really the main problem is the design, as it relies on warping the motherboard to provide tension for the CPU heatsink.
My only suggestion to this situation - at least for testing purposes - is to lay the motherboard flat on your workbench and put a CPU heatsink (with thermal compound, of course) over the CPU, but DON'T latch the heatsink down the motherboard (i.e. just have it sitting on the CPU.) Then see if any of the motherboard's symptoms / behavior changes when you do latch the heatsink down. If yes, you might indeed have some BGA issues.
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Old 05-21-2021, 12:43 AM   #4
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Default Re: Abit IC7 black screen

yea i have this board as well... i find it odd that the caps near and under the video card can get cooked when the radeon 9550 is a low power card with only about 15w tdp. better also check the psu for bad/unstable 3.3v and 5v rail! otherwise make sure the agp & pci slot area is cooled well with a fan directly near it because the radeon 9550 is a passively cooled video card and it will benefit from a fan circulating air near it.

and this abit board also does not have a metal backplate under the cpu socket to reinforce the board and prevent warping. only the asus boards have that. so it could also be a bad cpu socket warpage problem like momaka said.

this board also has a crappy fan on the northbridge heatsink that often seizes and fails, sometimes overheating and killing the northbridge chipset. is the fan on yours still spinning good?

EDIT: im also not sure if the mosfets by the agp slot overheated and fried when u replaced the bad caps with unsuitable caps that made the mosfets run very hot. u can also check the spot on the board directly underneath the 2 mosfets? shine a light on it or hold it under the light to catch the reflection and see if u can spot any discoloration or darkening of the pcb directly under where the mosfets are on the board. it might be hard to see because this is an all-black board. but if its discoloured, the mosfets may be fried.

Last edited by ChaosLegionnaire; 05-21-2021 at 12:50 AM.. Reason: added more comments.
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Old 05-22-2021, 10:28 AM   #5
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Default Re: Abit IC7 black screen

Are you sure you didn't cause a short circuit when soldering the replacement caps?
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Old 07-03-2021, 01:22 AM   #6
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Default Re: Abit IC7 black screen

It took some time to get back to this board, here are replies to your suggestions:
1. detach heatsink: this was my first idea, as soon as I saw MoBo bending I just stopped clipping them on and set SilentiumPC Spartan on top of the cpu, of course didn't do anything, but after running it for quite some time without GPU speaker sounds CPU HOT alarm, so I guess at least BIOS lives
2. RAM compatibility: as we know most, if not all, Abit boards are picky about RAM, some just make board don't respond, some make it beep and some just *work*, I picked out the promising ones and used them while testing
3. oxidation: every connector: RAM, PCI, AGP, IDE, SATA and others were first sprayed with isopropyl alcohol and after that with deoxidizer, when that didn't help I just sank the whole MoBo in isopropyl alcohol and cleaned it with a toothbrush
4. PSU: as you suggested I opened the PSU, it is a Chieftec GPS-400AA-101 A and saw one leaky capacitor, 6.3V 1000uF if I remember correctly, so it might have been messing with something, unfortunately it didn't help
5. PCI GPU: no, I unfortunately don't have one, I understand that it would be helpful to get one and check it, but MoBo without working AGP is still pretty much as good as dead
6. AGP slot MOSFETs and caps: I cannot see any discoloration of PCB, caps are grounded only on one side, not sure if original were low ESR, new ones certainly are, as to how hot MOSes get... Let me say as hot as Celeron D running for ~3sec without heatsink. Very hot to touch, but not burning, in comparison to CPU MOSFETs they get hot almost instantly, caps also get quite hot, but not as much. As to oscilloscope test without GPU: right one: D=3,37V, S=2,4V, left one: D=2,4V, S=1,54V; with GPU:right one: D=3,36V, S=2,4V, left one: D=2,4V, S=1,54V
7. NB: first of all, the board didn't have a fan attached to NB heatsink when I got it, I'm not sure how long did it work without it, but I saw it posting before I moved. The thermal paste under it was rock solid. NB core seems fine though, nether chipped nor discolored as far as I can see. I'm not sure if there are capacitors or resistors on the NB package but my meter tells me that when looking at the chip correctly (motherboard tilted 45degrees) three on the top side and three on the right side are shorted to ground.
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Old 07-03-2021, 05:37 AM   #7
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Default Re: Abit IC7 black screen

Capacitors on the NB package should not read short. Some may read a low resistance but normally they don't.

The caps that appear to be shorted on the NB, do you measure any volltage across them when the board is powered on?
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Old 07-04-2021, 11:07 AM   #8
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Default Re: Abit IC7 black screen

My bad, I was reading shorts on diode test, they actually wary from 20 to 26 Ohms, while 'non-shorted' are ~75 Ohms. The voltage on low resistance components is 2.6V, on others 1.4 to 1.6V.
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Old 07-05-2021, 12:59 PM   #9
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Default Re: Abit IC7 black screen

Those look reasonable
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