So today worked out pretty well, as I discovered a very small thing that was having a fairly annoying side effect, that being the machine misbehaving.
It's not so obvious in pic no 1, but have a look at the second EPROM back:
- IMG_20191019_120509.jpg (313.81 KiB) Viewed 4072 times
I only noticed as I caught it in the light just right. Pic no 2 shows just what the problem was:
- IMG_20191019_120554.jpg (173.56 KiB) Viewed 4072 times
And after some gentle manipulation, I plugged it back in and everything seemed much better
The list of fixes so far is:
1. Replaced mising sound chip. Channel A is silent under test, but B & C work fine. I'll test with another chip in case I have a duffer, but I suspect the problem is one of the nearby PCB traces that was damaged which still needs work.
2. Replaced missing Blitter. This all seems to test out fine.
3. Tweaked the contacts in the MMU socket, now I seem to be seeing 4MB ram all the time.
4. As above, fixed bent EPROM pin.
5. As the floppy connector disintegrated in my hands,I fitted a new one. Floppy works just fine now.
So what's left?
1. Fix the sound chip channel A problem.
2. Even with Eiffel, I can't get the mouse to work properly (KB is fine), either with a normal Atari mouse, or a PS/2 mouse. Could be a dodgy connection on the Megas RJ11 socket, I just don't know. I figure I need to wire up a spare ST KB direct to the board, see if that works.
3. Make a new wiring harness for the battery compartment.
So good overall progress, I think it'll be fully operational pretty soon. Once it is all running stably, I will look at some options, like a PAK install, possibly an internal IDE adaptor and maybe I'll even look at installing the DVI adapter board I have from Simon Monson. That would be quite a machine