It looks like a Twinhead CT-6020AN but with a different silkscreen. I guess it's a pretty common board layout, that may have been sold by many companies all from the same Taiwan manufacturer. It uses alot of standard logic. What components are bad?

Hello and thanks for the reply!
I was about to have a look and troubleshoot with an oscilloscope, however some ICs on the board have had their number/model number wiped out by - i guess - time?
They are completely unreadable (even with a microscope) so was wondering if someone here had the same card and could kindly post some pictures to allow me to identify what ICs there are.
Currently the screen is garbled when powered on together with my 5160.
I am suspecting one or more RAMs, but have no clue which ones they are as lots of codes have been removed from the chips.

That's the problem with Chinotaiwanese clones, there are hundreds of "noname" small time manufacturers producing the same hardware with little to no modifications to the original hardware they stole/copied from, often reusing leftover parts sold by their business partners that went bankrupt. They don't print labels to keep costs down so these are nearly impossible to identify. I have 8 MDA monitors under different brand names with identical case and chassis.
Just replace the RAM with known good ones, they go bad quite often.

I unfortunately don't know which ones ARE the Ram ICs at this stage, as there are some ICs without any writing on them.
I can sort-of guess that they are the ones that have specific common lines, but what if I'm wrong?

Gandalf 75 wrote on 2023-06-02, 09:48:

I unfortunately don't know which ones ARE the Ram ICs at this stage, as there are some ICs without any writing on them.
I can sort-of guess that they are the ones that have specific common lines, but what if I'm wrong?

The 4416 are the RAM Chips. However I would rather go a bit more systematically in diagnosing problems with the card. Do you have an oscilloscope? I would start probing clocks and outputs of the 6845, traffic on the RAMs data and adress line, looking at the logic chips.

I totally agree with you, however in order to troubleshoot the logic chips I would look at their data sheet, but how can I do so on ICs like these?

Gandalf 75 wrote on 2023-06-02, 10:09:

I totally agree with you, however in order to troubleshoot the logic chips I would look at their data sheet, but how can I do so on ICs like these?

True... that's somewhat annoying.

EDIT: I can only find low res images on the web of this card, so no easy way of getting labels for these ICs.

I was hoping someone here would have the same card in better condition with all IC labels on them 😀

Well, 74 series logic has Vcc and GND always on the same pins. The in- and outputs should still look sensible. Even if you don’t know which IC in particular you are looking at. Hope is that it’s some other problem anyway. I would start somewhere, on one of the chips that you DO know what it is. And then work your way through the board.

Personally, I would get a schematic of a CGA card like IBM's, and identify the obvious key components and check for sync and color signals. You could do this without a picture of a card, and probably can figure out what the ICs in question are even though they are blank!

But if you would like, here is my version, but you notice that with all the standard logic, they'll shove in whatever IC they had in the bin on that day. The thing to note is the boards layout looks identical, and they were made about the same time.

Also, you could stick in a mono card simultaneously with the CGA and boot in mono, and then run debug and fill the CGA memory with 1's and 0's, to find if that is working or not. However, I'm guessing your problem is more fundamental, like no screen? Check the signals at the connector.

the3dfxdude wrote on 2023-06-03, 22:45:

Personally, I would get a schematic of a CGA card like IBM's, and identify the obvious key components and check for sync and color signals. You could do this without a picture of a card, and probably can figure out what the ICs in question are even though they are blank!

But if you would like, here is my version, but you notice that with all the standard logic, they'll shove in whatever IC they had in the bin on that day. The thing to note is the boards layout looks identical, and they were made about the same time.

Also, you could stick in a mono card simultaneously with the CGA and boot in mono, and then run debug and fill the CGA memory with 1's and 0's, to find if that is working or not. However, I'm guessing your problem is more fundamental, like no screen? Check the signals at the connector.

Thanks this helped a LOT!