exxos's Atari, Amiga & retro forum

Hi there.
I have a bad ram ship on my ATARI STF motherboard C103414-001 REV 1 When I use the test cartridge here is the screen Do you know how to detect the faulty RAM ?

Any help welcome.

Considering all the random bad bits. Have you tried simply reseating the MMU ?

It’s not a MMU problem.
To be precise i installed new ram on bank 2. The diag cartridge shows 1MB, all connections fine but when testing i have these errors.
So (because perhaps some chip were solded with too hot air) i’m quite sure I destroyed one of them.
Because soldering there SOJ ram are really a nightmare I wondered if there is a way to detect the faulty ram before removing and replacing each one after another… ?

You should have mentioned you fitted half the memory in your initial post...

Well, you have 4 bits per chip. So going by your screenshot alone.

0,1,2,3 = 4 bits 1 chip faulty.
4,x,6,x = 2 bits 1 chip faulty.
8,9,10,11 = 4 bits 1 chip faulty.

It's why I thought you would more likely have a RAS/CAS type of fault as its heading to the whole bank being faulty. But as you say you fitted them, then I would surmise all the chips you fitted are either faulty, or badly soldered or shorting out to other pins, Or there are resistors to fit on RAS/CAS etc when upgrading to 1MB which have been missed. I am not familiar with those SMT boards personally. Good luck.