Tuesday, March 18, 2014

Wanted: Dead or Alive

Second in line is an A2630. This is an 030/FPU accelerator which came with the faulty B2000. Symptoms are that when installed, the Amiga does not boot (tested on a working B2000).

History of this card that it was claimed to be working, until someone decided to upgrade the FPU to a faster one. An oscillator socket was soldered to the board and the FPU replaced. The board then refused to boot.

Initial diagnose here was a faulty FPU. In the course of that repair, all the modifications were reversed. Still the card wouldn't boot. That's when it fell into my hands.

The plan is to check the signals of the 68030 and FPU and check all the PALs and replace them for GALs if needed. The A2630 is one of those cards which schematics and jed files are all over the net.

But first to repair the B2000 so it can act as a testing platform.

Zombie Amigalypse

First up is a B2000, rev 4.1 motherboard. Symptoms are black screen. When pushed on MB around Agnus, ROM, 68k, the Amiga either boots or shows a green screen.

Initial diagnose: Faulty Agnus(socket), bad PCB traces.

Swapping the Agnus did not result in an improvement. Looking at the board resulted in a couple of observations:

1) The board has had a 1 MB Agnus modification
2) Someone didn't really understand those instructions and also pulled pin 41 of the Agnus socket (only needed on A500 models).
3) There was a big scratch running through 2 traces between ROM and 68k.

I couldn't really test the continuity of these traces, so I just scraped, cleaned and retinned them to see if that worked. If so, I would solder a copper wire on top of it and recoat it.

Here also no improvement on the symptoms.

Then I went ahead to replace the Agnus socket. Too bad I seemed to have run out of them, so i'm waiting for replacements.

Hopefully some better news next time.

Monday, March 17, 2014

Start Amiga Repair Blog

As of today, all my amiga repairs and custom hacks will be published on this blog. It will be a kind of database for me how I repaired Commodore Amiga computers. And hopefully to share knowledge of repairing these 20-25 year old machines.