My disk drive was working fine this morning, but now it does not even spin. The screen shows a sort of moving checkboard, but it goes to basic fine.
When I turn the computer off the disk drive light briefly flashes. Otherwise nothing... is this more likely to be a broken drive, or a broken card?
First of all check that Your PSU works properly by measuring voltages; does it tic tics when You power on Your Apple ? If Yes You either have a PSU fault or a short circuit.
I would first remove the controller card and test the Apple II , if it powers on regularly, turn it off, unplug the drive from the controller card and insert it in slot 6 of Your Apple II.
Turn it on and press reset. Does it show a basic prompt?
If Yes , invoke Monitor with a CALL-151 command and list the drive controller prom code with a C600L command and compare it to the original code.
It it lists ok , it does not mean that the controller cars is totally ok but its a step forward.
Do these checks and report :)
Luca