A2000 help please

[stephen_usher]

You would need a diagnostic program into which you can put a memory range to test the upper half megabyte.

[Maximilian]

Just use Diagrom for this.

[Steve_w]

I knew U511 was dead on row 2 (D10), and when I put a working chip in the socket for U511 I would get a yellow screen so I thought that maybe the faulty chip in U511 is hiding a further fault in this row further along and when a working chip is put in U511 the further fault shows up. I piggy backed the rest of the chips in row 2 (U512-U516) and the yellow screen went and I got the KS prompt, ATK would boot and I now had 512k chip RAM and 512k slow RAM - Yes I had done it!!

I removed the piggies one by one until I identified the faulty chip as U516 (the last in row 2).

I thought I would post the answer as it maybe helpful to others in the future. I think I was lucky as all the faulty RAM chips failed in a way that piggy backing worked.

Thanks to the members for helping me during this topic, much appreciated, my first A2000 fixed Battery damage, a faulty 74LS245 and 11 faulty DRAMs !!

11 new DRAMS

final ram.jpg (94.3 KiB) Viewed 72 times

1Mb

1mb.jpg (105.02 KiB) Viewed 72 times

[PhilC]

Well done with the fix @Steve_w , I was looking on with interest at this one.

[rubber_jonnie]

[stephen_usher]

[Maximilian]

Nicely done!