Hi all,

so this VGA card found its way to me and it's giving me headaches. It is the only card with a Macronix chipset in my collection and the 86000 in particular seems to be relatively rare. So it would be a shame to give up on it.

I have tested it in various motherboards and the symptoms are as follows: The boards give me a long-short-short WITHOUT the card. So, as expected. With the card inserted I get a seemingly normal POST (judging by the beep pattern which is the same with a healthy card) but the screen stays blank.

Here's what I did so far:

• Looked long and hard at all traced. Found nothing.
• Cleaned the ISA pins with IPA. Then again and then some more. 😀 Doesn't look like it, but so help me, they should be clean! 😀
• Measured continuity between all pins of the MX86000 and the pads. All seem OK.
• Measured 5V on the ICs. Present.
• Swapped the crystal with a known good one. No difference. Put the original one back in.
• Socketed the two LS (U5 & U11), the driver IC near the crystal (U6) and the Music DAC (U9)
• All four RAM chips test fine (Retro Chip Tester)
• The two LS74 245 test fine (Retro Chip Tester). I even swapped them with two new ones without success.
• Swapped the DAC with a known good one without success. Test card works fine with the DAC of the Macronix card.
• Backed up the ROM, looks good (attached to this post)
• Measured all VGA pins for continuity on the pins-to-PCB level, looks good.
• Removed the driver IC (U6). Board goes long-short-short. Put it back in. Board POSTs.
• Removed the ROM BIOS. Board goes long-short-short. Put it back in. Board POSTs.
• Removed the first RAM IC. Board POSTs normally. (Hmmm...) Put it back in.
• Removed the 74 245 below the RAM. Board POSTs normally. (Hmmm...) Put it back in.
• Removed the 8 tantalums. They are already missing in the picture. No difference. I need to put replacements in at some point obviously but would like to avoid the hassle right now as long as the card appears "dead".

What I'd like to try is to replace the BIOS. Maybe it checks fine in terms of "the board sees it" but the data is defective, failing to properly initialize the card.

Any input welcome. Unfortunately I do not have an oscilloscope. Only a Fluke 17B+. Sorry about the residual flux mess on the back of the card... I will properly clean it once I'm done... not worth it right now. Some solder found its way on one of the unused ISA pins on the back of the card. Just mentioning it because it sticks out a bit.

Thanks! 😀
Jens