128K Toastrack Lower RAM Fail

[tridy]

Thanks for the reply!

I am learning new things .

I think that from the 10 assorted chips I got from Ali, I have one like this, which should work, I think:

so, when the sockets arrive and the testing tool, I will test it and then see if it works in the toastrack.

I will update about the progress.

[tridy]

Also, the Fruitcake ram test rom is pretty useful. You don't have to plug it in externally - just replace the onboard ROM with it.

I was wondering how different is "Fruitcake ram test" compared to ZX-Diag in terms of functionality?

[tridy]

Hi.

I have finally received the memory modules and sockets.

I have socketed the first 8 modules, and tested them with the tester and they were OK.

Then I inserted the memory into the sockets, started the Tastrack, and got the same garbage on the screen.

On the third or fourth time while I was testing the voltages on the board I eventually got the picture. I started slightly pushing the chips down and all RAM chips did not have any effect. However, pushing the AY module crashed it.

I have to say that initially, my problems started after I tried to solder in the stereo mod onto AY chip + ULA and there is a chance I shortened something in the process. I was not sure what it was and diagnostics showed that one of the lower RAM chips are dead, so I took that as the best hint that the problem was there. Now I have figured out that it is not the RAM that is the problem. My bad, I should have noted the AY short incident in the beginning.

I am posting another question in a separate thread about AY chip, not to confuse with this thread about Lower RAM Fail:
https://sinclairzxworld.com/viewtopic.php?f=21&t=4492