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| IICX Restore - Graphics issue |
Posted by: smrieck511 on 2026-06-05 07:12:06
I recently got a IICX DOA from eBay. Recapped the logic board, graphics card, power supply and floppy drive. Cleaned it up, put it all back together and thankfully got a nice boot chime with no issues other than the fact that I'm just getting a blank white screen on the monitor. I noticed when I plug the monitor in NOT connected to the graphics card I don't even get the white screen (just a black screen) so my assumptions at this point are the logic board is OK and the issue is on the graphics card. My instinct says it could be bad VRAM chips? In other words it's trying to do something but it can't even get itself to 4bit/16 colors. Am I thinking the wrong way here? Anybody know of anything obvious with a BCGM0322 high resolution display video card? is it at all possible there could be something on the logic board causing this instead of the graphics board? |
Posted by: smrieck511 on 2026-06-05 07:26:28
What is this heresy ChatGPT is talking about?? Could there be any truth to this? never heard of such a thing. it's true, I haven't attached a startup disk yet. If all was working correctly, I should expect a cursor and flashing ? ... shouldn't I?
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Your suspicion about bad VRAM chips isn't out of the question, but there are several other highly probable culprits before assuming the BCGM0322 High-Resolution Video Card is dead: [1]
- No Startup Disk: The system gets past initialization, chimes, fails to detect a bootable floppy or SCSI drive, and halts. This often defaults to a solid gray/white screen on older Mac OS versions instead of the blinking question mark. [1, 2]
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Posted by: Durosity on 2026-06-05 07:44:46
I wouldn't trust any AI answer when it comes to vintage stuff like this. It'll often spew a lot of hallucinated garbage because the topic is niche and it really doesn't have any training on said topics.
Do you have an alternative graphics card you can test it with? Just because the screen displays an image doesn't mean that the GC is actually outputting anything meaningful. Also have you tried the GC in the other nubs slots?
On the flip side, do you have an alternative screen you can try it with? It's entirely possible the card is working but the screen can't process the image correctly.
Have you tested the voltages that the PSU is outputting? It's plausible that they're a bit outta spec and that's throwing the card into an error state.
Finally do you have a hard drive to put in it? I wouldn't expect it to relate to the issue chatgpt said as realistically the video should be initialised before the OS even boots, but it'd be interesting to see if the HD makes sounds to suggest the Iicx itself is actually booting or not. |
Posted by: smrieck511 on 2026-06-05 10:58:55
I wouldn't trust any AI answer when it comes to vintage stuff like this. It'll often spew a lot of hallucinated garbage because the topic is niche and it really doesn't have any training on said topics.
Do you have an alternative graphics card you can test it with? Just because the screen displays an image doesn't mean that the GC is actually outputting anything meaningful. Also have you tried the GC in the other nubs slots?
On the flip side, do you have an alternative screen you can try it with? It's entirely possible the card is working but the screen can't process the image correctly.
Have you tested the voltages that the PSU is outputting? It's plausible that they're a bit outta spec and that's throwing the card into an error state.
Finally do you have a hard drive to put in it? I wouldn't expect it to relate to the issue chatgpt said as realistically the video should be initialised before the OS even boots, but it'd be interesting to see if the HD makes sounds to suggest the Iicx itself is actually booting or not. Thanks. I'm gonna check the PSU voltages when I get home tonight. Unfortunately no other cards or DB-15 monitors (or adapters) at the moment. |
Posted by: smrieck511 on 2026-06-05 18:08:40
not seeing anything obvious. At least for me. |
Posted by: croissantking on 2026-06-05 18:26:01
Have some of the through hole parts been reflowed? The PDS connector & VRAM sockets look a bit odd. |
Posted by: smrieck511 on 2026-06-05 19:04:26
Yeah i did reflow all of that today. No bridges. |
Posted by: smrieck511 on 2026-06-05 19:52:14
Recapped Power Supply is putting out 5.1 v and 11.94 v.
floppy drive is also working flawlessly with cleaning and new eject gear. Ejects blank disk on boot. |
Posted by: Durosity on 2026-06-05 22:44:01
Recapped Power Supply is putting out 5.1 v and 11.94 v.
floppy drive is also working flawlessly with cleaning and new eject gear. Ejects blank disk on boot. That at least suggests the Mac is working, although it’s possible there’s a NuBus issue.
I assume you can’t test the card on another Mac either? |
Posted by: smrieck511 on 2026-06-06 03:12:52
That at least suggests the Mac is working, although it’s possible there’s a NuBus issue.
I assume you can’t test the card on another Mac either? actually I do have another spare IICX board. It just doesn't have any caps on it at the moment. |
Posted by: croissantking on 2026-06-06 03:24:59
actually I do have another spare IICX board. It just doesn't have any caps on it at the moment.
Recapping it is probably the next job, then you’ll know if it’s the video card at fault or not. |
Posted by: smrieck511 on 2026-06-06 03:28:28
Recapping it is probably the next job, then you’ll know if it’s the video card at fault or not. good point. Will do this week but I need to order more caps unfortunately. Any chance these will at least run without caps like an SE 30? doesn't even have the axials. |
Posted by: croissantking on 2026-06-06 03:39:38
good point. Will do this week but I need to order more caps unfortunately. Any chance these will at least run without caps like an SE 30? doesn't even have the axials. I’m not sure if the soft power circuit will function without caps, so you might not get it to start.
You could always try booting it and see. I’d probably try to be patient and just wait for the caps to arrive though. |
Posted by: smrieck511 on 2026-06-06 03:49:01
OK also I'm gonna check the Nuchip and nubus slots with the scope. Any idea which pins I would need to check specifically? If not I can go through the schematic. |
Posted by: Durosity on 2026-06-06 04:19:10
Nah I know from experience it won’t boot without caps… well not without a soft boot modification.
Also do you know for sure this other IIcx Board is good? It’s plausible it could have another similar issue. |
Posted by: smrieck511 on 2026-06-06 08:34:17
Nah I know from experience it won’t boot without caps… well not without a soft boot modification.
Also do you know for sure this other IIcx Board is good? It’s plausible it could have another similar issue. yeah not sure if the status of the other board. They both look pretty good. I have the one that looks better currently installed with caps |
Posted by: Durosity on 2026-06-06 09:17:35
I assume you don’t know anyone who could test the card/motherboard with another system do you? Where do you live? |
Posted by: trag on 2026-06-06 21:03:20
If it is outputting pure white, either
1) the IIcx boot process is not proceeding far enough to give you a mouse cursor and disk request icon,or
2) I would think that an input to the video card DAC is stuck high. That BT chip is the DAC. It should be getting data from the VRAM chips, but it probably passes through some 74 family logic on the way. I would find those 74 series chips and replace/ttest them.
for #1 have you tried having a bootable floppy in the drive at boot time? |
Posted by: smrieck511 on 2026-06-06 21:11:44
If it is outputting pure white, I would think that an input to the video card DAC is stuck high. That BT chip is the DAC. It should be getting data from teh VRAM chips, but it probably passes through some 74 family logic on the way. I would find those 74 series chips and replace/ttest them.
All that assumes the IIcx bongs on power up
That's very helpful thanks! I will check it out. Yes it does give a consistent happy chime. |
Posted by: trag on 2026-06-06 21:12:41
That's very helpful thanks! I will check it out. Yes it does give a consistent happy chime.
Edited a bit since then... Sorry for not getting my thoughts complete the first time. |
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