> Usually the PROGRAM LEDs didn't blink like that. It only happened 3 or 4
> times.
Yes, this is also similar to the symptoms my machine exhibits.
> But I've very often experienced a switch back to A1, after 2-5 minutes. The
> alternative was three PROGRAM LEDs lit at the same time.
...and that's pretty much what my machine does all the time. Sometimes it
takes only a few seconds, sometimes longer.
I've swapped IC27 with a salvaged 4560 now. D/A calibration seems to work
fine now but I still get the other symptoms.
I've also finished a second board; so far this seems to work stable
(although I probably should do a burn-in test before making final judgement
about this).
There are a few more observations but I want to verify them before posting
them.
Just a quick question: Is the RAM (IC32) only used for patch storage? The
actual "workspace" RAM is in the 8049 itself?
--
Malte Rogacki