Floppy Drives

[Castellen]

The ports should be pin compatible.

Make sure there is power at the port first, +5V on pin 12 and +12V on pin 23.
If there is no power, check fuses F350 and F351 are not open circuit.

Make sure jumper J351 is set in the DF1: position, otherwise DF1 will not be not return a positive poll when the system powers up, so it will report there is no DF1.

[Castellen]

Sounds like something is causing the ready line to be pulled low when SEL2 is polled during power up, casuing the system to think there is a DF2.

Perhaps the faulty internal drive is causing these problems.  Or perhaps the there is a problem with the floppy controller, which is why neither of the two drives are working correctly.

If you haven't done so already, check Paula (U400) and it's socket for corrosion, as it's located right beside the leak prone RTC battery.

It's also worthwhile swapping the two CIAs over as one could have an I/O pin problem.  If the floppy starts working, but the parallel port or something now fails to work correctly, you'll know there is a CIA fault.


Reseat all the socketed ICs on the motherboard, as IC sockets are bad for developing intermittent problems which can cause strange things to happen.


Other than that, I can't think of any other reasons why the external drive won't work on the A3000.

[Castellen]

I've repaired a few A3000s with floppy problems due to IC socket corrosion.
Remove U400 and U450 and carefully inspect each socket contact.  They should all be silver and shiny.

If there are any signs of green corrosion, then the socket needs to be replaced.

Normally I remove the socket and fit the IC directly into the PCB.  A far better soloution as there's no unreliable contacts to worry about ever again.