best way to test vdp's

[+arcadeshopper]

I picked these up.. wondering if there's a best practice to test beyond stuffing each one individually in a 4/a and running ti diags.

 

Greg

[fabrizio]

To test the tms9929, I use the ti99 with a zero insertion socket.

[+Ksarul]

Looking at the markings, I suspect you may have issues with some of the chips in the left picture. Something feels just slightly off with them (they may be fully functional, but they are probably fakes). The group on the right doesn't give that vibe--but you won't know for sure until you test them. I like @fabrizio's solution. I may have to modify one of my spare consoles to support that (and  look for a 64-pin ZIF to do the same with the CPU). Thinking on that I may actually already have a 64-pin ZIF around here somewhere. . .I think Burndy made them.

[GDMike]

"There embedded with ease dropping, file sharing, bank account grabbing, personal information grabbing, nuclear science and health technology grabbing

           "SPYWARE" ooooooooohhhhhhhh,.

Then again, they just may be fine .

Hehehehe.... I couldn't help myself...

Lol

 

[cbmeeks]

I don't recommend testing in a real TI because if these are fake, there's no telling what pins do what.  For all we know, it could have a dead short across VCC and GND.

I recommend you check out Noel's video on testing possible fake TMS9918/29 chips.  Basically, he just builds a small circuit that will generate a colored screen.  If that works, good chance it's real and safe enough to test in a TI.

 

 

[+arcadeshopper]

so far they all seem to have the same basic resistance on the 2 sets of pins.. which is good. will have to build a test unit 

[GDMike]

It's a great video, I'll have to do the same. Just to have it. Maybe make a permanent solution test board for my use. 

Edited December 31, 2020 by GDMike

[fabrizio]

I use a ti 99 as a forklift to do some tests, for the micro I used a socket with a tulip pin, but if I find a zero insertion socket I try it ... As for the TMS9929 I bought 10 in china, they work everyone, incredible. While the first 5 purchased some time ago, only 1 worked ....