Hey all,
I have just gotten my hands onto a collection of amigas that also included an a2000 with battery damage. I have removed the battery and fixed all connections, but the board is still dead (mostly stuck at the green screen, sometimes its yellow).
All connections test fine when measuring continuity with my multimeter from the CPU to U101 (Fat Agnus), so I don't think there's a problem with those.
I have also tried using a debug rom (V1.21), which outputs the following (and every 100 runs or so it also detects errors with the UDS/LDS test):
Garbage before this text was binary numbers: 1, 2, 4, 8, 16, 32, 64, 128, 240, 15, 170 and 85
To help you find biterrors to paula. Now starting normal startuptext etc
Amiga DiagROM V1.2.1 - 16-Jul-20 - By John (Chucky/The Gang) Hertell
Testing if serial loopbackadapter is installed: <> NOT DETECTED
- Parallel Code $ff - Start of ROM, CPU Seems somewhat alive
Checking status of mousebuttons for different startups:
Set all Interrupt enablebits (INTENA $dff09a) to Disabled: Done
Set all Interrupt requestbits (INTREQ $dff09c) to Disabled: Done
Set all DMA enablebits (DMACON $dff096) to Disabled: Done
Testing if OVL is working: OK
- Parallel Code $fe - Test UDS/LDS line
- Test of writing word $FFFF to $400 OK
- Test of writing word $00FF to $400 OK
- Test of writing word $FF00 to $400 OK
- Test of writing word $0000 to $400 OK
- Test of writing byte (even) $ff to $400 OK
- Test of writing byte (odd) $ff to $401 OK
- Parallel Code $fd - Start of chipmemdetection
Addr $00058400 OK Number of 32K blocks found: $0B
Startaddr: $00000400 Endaddr: $00057FFF
- Fastmemcheck skipped as we found chipmem
- Parallel Code $fb - Memorydetection done
Using $00044CEA as start of workmem (Base)
- Parallel Code $fa - Starting to use detected memory
m0n;
After the "- Parallel Code $fa..." it sometimes hangs, and sometimes just prints random junk.
The only real concerning part of the test I see is "Startaddr: $00000400 Endaddr: $00057FFF". I assume Endaddr should be something more like $000FFFFF?
This number is also different between different runs of the debug loop.
I have looked around the board with my oscilloscope too, but found nothing obvisouly out of the ordinary.
Has anybody got some ideas or tips as to how i can get the machine up and running again?
P.S. it's not a problem with any of the chips, I have swapped every single one over to a spare A500 and everything works fine there.
