I take that back. It is the DRAM. But which? I cannot bulk replace because this DRAM is obsolete and eBay has outrageous prices. 35ns is also too fast to just use sacrificial EDO sticks as a source since these are 80 or 70ns. 60ns top. I cannot test them with a small C program writing into the memory and reading back because portions are write only. And there are no THT SOJ40 sockets to be found. I could use the SMD sockets and then either make my own EDO sticks to use memtest86 on or I could use a blue pill stm32 board to build a crude tester
So to summarize:
Card 1, the orange one, had bad glitches even in 2D. I fixed some loose pins on the 2D ASIC and now it's dead as a doornail. Just completely hangs on post with not so much as the BIOS complaining about it. Wish I knew where my POST card is.
Card 2 works in Windows, until you start a 3D accelerated application where it shows texture glitches until it hard crashes the system. That can be triggered by blasting the middle DRAM with hot air.
Card 3 has an FRJ texelFX with broken off pins, which could be rescued with fine enough power tools (think dentist drill). Works fine in 2D.
Card 1, the orange one, had bad glitches even in 2D. I fixed some loose pins on the 2D ASIC and now it's dead as a doornail. Just completely hangs on post with not so much as the BIOS complaining about it. Wish I knew where my POST card is.
Card 2 works in Windows, until you start a 3D accelerated application where it shows texture glitches until it hard crashes the system. That can be triggered by blasting the middle DRAM with hot air.
Card 3 has an FRJ texelFX with broken off pins, which could be rescued with fine enough power tools (think dentist drill). Works fine in 2D.
I need to think about the best course of action for a while. I'm tending towards making a crude in circuit tester. This would not be able to push the DRAM to its timing limits, by far. But at least indicate a gross fault in a memory cell.
Oh and I also need to get a very fine Dremel.
Another idea is to pull off the FRJ from the orange card and use it as a replacement on the other one. This way I might have at least one working card. Unless of course that has issues with the RAM, too. Which, given how these have been mistreated, is very likely. And pulling any of those big ICs off runs the risk of damaging them. So I'd very much do as little IC swaps as possible.
Oh and I also need to get a very fine Dremel.
Another idea is to pull off the FRJ from the orange card and use it as a replacement on the other one. This way I might have at least one working card. Unless of course that has issues with the RAM, too. Which, given how these have been mistreated, is very likely. And pulling any of those big ICs off runs the risk of damaging them. So I'd very much do as little IC swaps as possible.
Bun's Lab
I need to think about the best course of action for a while. I'm tending towards making a crude in circuit tester. This would not be able to push the DRAM to its timing limits, by far. But at least indicate a gross fault in a memory cell. Oh and I also need…
Well, I did it. Now it only has to work. Will see about that later. Bbl, garden
I painstakingly went through each and every pin thrice to make sure they are all soldered down, make contact with the pad and that there are no solder bridges. Yet it doesn't work. The chip revisions are different. Geez. Hours wasted
What looks like bridges are just flux residue and isopropyl alcohol. Am aware of those tilted pads. Again, everything checks out electrically.
Bun's Lab
The other damaged pins just fall off one after the other
As to this: get a fine enough Dremel tool, attach new wires to the internal die to pin connections, hold it down with epoxy, then I can solder it back on. I suppose it helps having it off the board now.