bofh.fromhell wrote on 2022-07-21, 21:17:
Have you checked for lose connections on the memchips?
You can sometimes find cracked joints if you squeeze the chips and the picture changes.
When it comes to replacement chips, its probably easier and cheaper to find a donor card.
The Ti 4xxx series are getting pretty rare now 🙁
Sorry to bump this thread after so long but I'm doing the same thing and I think it's worth sharing. My Ti4200 came from a scrap parts box and it doesn't work, some RAM chips look like they've been bashed and the display is all messed up.
I have a lot of AGP and PCIe cards though, so I went through the collection for similar speed ratings of DDR from a similar era - the Ti4200 is tougher than some because TSOP-II / TSOP-66 fast DDR RAM had a short lifetime with the move to BGA. I did however find a very closely matching part on a Powercolor Radeon 9600 EZ 128MB card - which has 3.6ns DDR: https://pc-1.ru/i_shop/video/agp_512mb/A048305
As I looked deeper at the datasheet for the HY5DV281622DT, it seems that it's 128mbit comprising of 4 banks each having 2mb and 16-bits wide - which matches the Samsung K4D28163HD seemingly perfectly. It has an operating voltage of 3.3v with 2.5v for signalling which means these both might be Graphics DDR possibly:
The pinout is the same:
Compared with similar DDR chips from the era, DDR which runs at 3.3v and uses 2.5v for signalling seems to be pretty rare, they all moved to lower operating voltage very quickly and all the DDR you'll find on RAM sticks is 2.5v operating and 2.5v signalling. Good news though, it seems that UTsource have a few in stock and they're cheap enough for the 3.6ns variant:
This Radeon 9600 seems to work and I don't want to take its RAM off, so I continued looking through the pile and found a similar candidate / route, later Hynix chips on a Radeon X600 PCIe that I won't feel sad about borrowing parts from. It has the later or cheaper HY5DU281622ET memory, which drops the operating voltage to 2.8v (hmm, although that's both signalling and VCC so this probably can be found on good DDR400 or faster memory sticks). I'm thinking I'll try to figure out how to change the RAM voltage on this Ti4200 then borrow all the RAM from this card - here's all 3 together for a good reference:
edit: huh, the only other close up pics I can find of this 9600 EZ card show it has 5ns RAM, gonna check out whether it's running the RAM at 2.5v instead. In which case I'll steal the RAM off this 9600 and put some RAM from a DDR-400 memory stick in its place.
