I got this MST with strange behavior. It won't boot at all and cycles through the same "signal loop" i.e. every 8µs (= 64 CLK8) it shows the same picture on the scope:
I checked other signals (with the pink colored probe) which are:
/DTACK = always 1
/HALT = always 1 (except whe Reset button is pushed)
/RESET = always 1 (except whe Reset button is pushed)
/UDS = /LDS = R/W = /AS (regarding level and timing)
A[1..23] = always 1
So it looks like the 68000 wants to write a 16bit word at $FFFFFE! Of course the missing /DTACK upsets Glue and it pulls /BERR low after 64 CLK8.
CPU, MFP, PSG and FDC got sockets at some time - there might be a problem here. But I cannot locate it.
I checked the signal lines from CPU -> Glue -> MFP by now. Looks fine.
Blitter is removed and both solder bridges are closed.
And yes: I cleaned the PLCC sockets and swapped ICs with working ones from a 1040