A1200 floppy drive problem

[jltursan]

I'm trying to fix an A1200 with a weird floppy drive behavior.

The machine, from a workbench floppy cold boots fine, workbench loads and both drives, internal and external start to click periodically.
Both drives seems to work, new floppies inserted are recognized by workbench and can be read.

After 1-2 minutes, the click start to behave erratically, leds can turn on/off and the motor hiccups of both drives can be heard. Never is the same; but the fault is always noticeable when it starts.

I've replaced all the capacitors, repaired a corroded track in the floppy area, replaced a 74LS86 at U26 and socketized/swapped/replaced both CIAs. I don't want to believe it's a Paula failure

Has anyone any idea or previous experience with this kind of problem?

[jltursan]

Oh, damn, indeed the A1200 seems to have a 4 layer board. The corrosion wasn't so bad; but maybe there is more damage that can't be seen. Of course I'll need to double-check ALL the wiring of the floppy circuit :hammer:

The thing is that it broke suddenly while formatting a floppy, my guts are telling me that's some fault in the logic

[jltursan]

I thought about it; but it's an A500's heavy brick that works fine with other machines. Seems good.

Given that the wreck happens at the same time at both drives, internal and external, it must narrow a bit the search.

I was also thinking in checking some signals, I would like to know which one drives the led...