Dead A2000

[sev]

Hey all, I recently scored 2 a2000's and an a2500 from craigslist. The a2500 is in good working condition but Ive been working dilligently to get the other two a2000's working.

For the sake of this thread, Im going to focus on the A2000 with the Rev 6.1 mobo. It had moderate battery acid damage, which i cleaned up, to reveal most all the traces are in good condition.

The a2000 in question is doing the usual black screen business. You switch it on, nothing happens. The LED remains dim, and thats about it.

 I went ahead and replaced the socket for the 68k tested each pin front side and back side of board for continuity and confirmed all pins work good with a multimeter.

I took every single chip and the power supply from the dead a2000 and transfered it to the a2500 and the a2500 booted up and ran... So all the chips and power supply I can confirm are good. I just dont know what else to do. The socket works, all the chips work, jumpers are set correctly...etc.

one thing i find peculiar. If i yank the 68k out of the socket and power it on, the led starts out dim, then goes bright, and at the same time the LED goes bright the disk drive seeks track 0 and sits with the light on. That's it. nothing else.

Any help would be appreciated!

[Azryl]

Removing the 68k from its socket will make the a2000 seek an accelerator/better cpu during boot. I could be wrong, usually am

If you had a zorro based accelerator then you could check if it is a problem with traces around the 68k socket.

Az

[ElPolloDiabl]

I did a search for info on repairing an Amiga 2000 after battery damage...
It's possible the acid leaked right in and cut some of the tracks.
Do you have a logic probe to check continuity?

[sev]

i have a gvp 040 board, when i pop it in, it tries to boot, the screen does this weird wavey purple thing. (ill post up a youtube video)

i do not have a logic analyzer

[sev]

Removing the 68k from its socket will make the a2000 seek an accelerator/better cpu during boot. I could be wrong, usually am

If you had a zorro based accelerator then you could check if it is a problem with traces around the 68k socket.

Az

so i yanked the 68k out of my working a2000 and kept the accelerator board in there, it didnt boot (blank screen), so i dont think this works.

after much fiddling around with the 68k on the dead A2000, i got some very bleak signs of life, when i first turn it on, the screen flickers then it popped up different colors, first red, then purple, then green.

so i turned it off, reseated the cpu and got a purple screen and a sound from the disk drive every few seconds, but not like when the kick star rom looks for workbench

i removed and reseated the cpu again and all is dead. this is getting frustrating.


here is the video:

https://www.youtube.com/watch?v=wQeM-JKozBo&list=UUrDbA-kAeYmHs6FkUJ90PqQ

[Plaz]

You could be dealing with more than one problem. If you make it all the way to the green screen that usually means the Agnus chip is failing. Often a reseat will correct that. If your floppy spins endlessly, then one or both of the CIA chips could be bad. Carefully check if one seems to be running hotter than the other. Not always an accurate test, but quick and simple.

PS. I think I recall a diode, right side, at the back, edge of the mother board that could get zapped if cables were plugged incorrect in the back. So many Ami boards so many years ago, I might be mis-remembering that one though.

Plaz

[amiman99]

You said that you have some battery damage, maybe you should take a 2in radius around the battery and use the SOLDER SUCKER to remove old solder from the chips and add new solder to it. Especially around the 68000 socket.

See if that helps.

[sev]

You said that you have some battery damage, maybe you should take a 2in radius around the battery and use the SOLDER SUCKER to remove old solder from the chips and add new solder to it. Especially around the 68000 socket.

See if that helps.

so I took every single chip from the dead a2000 and put them into the working a2000 and it worked just fine.

I have a feeling the problem lies somewhere else. I have soldered in an entirely new socket for the 68k on the dead a2000.

I have, however, not replaced the solder on anything else. Maybe that's the next step, but all the components i checked that had corrosion on them have continuity.

[Plaz]

The pins in the sockets themselfs can corrode especially those near the battery. I've repaired serveral A2000's by replacing the CPU socket. Check sockets closely with a small flashlight. If the plugins aren't silvery clean, may need a replacement.

Plaz