Reply 20 of 49, by Deunan
Joakim wrote on 2021-05-24, 11:52:
I am a little confused about the section about the power on page 11/19. I have a 4 pin Molex connector on my model, but I also have the 10 pin molex connectors. Is 4 pin molex is enough? Maybe the other connectors are there for compatibility reasons?
It looks like your drive needs DC only and it's the usual +5V and +12V - see section 7.0 in the PDF. That's good. On old model like this it's quite likely there are 2 separate power connectors for different systems. It seems you might have 3 of those, the PC-type Molex and two 90deg pin connectors. Not sure why J2 is there but J5 should have the same pinout as in the PDF. You can easily test the standard Molex then, middle pins should be GND, one side +5V (plug in a cable to make sure it's on the red wire side), the other side +12V. To make double sure you can trace the +5V to the logic chips, most TTL series have power input in the last pin (14/16).
If the power plug seems OK then connect just the power and see what it does. Preferably you should be doing it via a current-limited PSU because if there are any faulty tantalum caps there will be fireworks. Not too worry if that happens, can be usually easily repaired by cleaning the soot and replacing the offending part. With current-limited PSU you can see the excessive power draw and act before there is actual fire though.
Assuming no fireworks, put in a floppy and close the drive door. If there are issues with inserting a floppy investigate rather than use force, only drives that eject disks need a gentle push at the very end of floppy travel, everything else should be butter smooth. There should be no need to keep pushing the floppy to close the door in any kind of drive.
Most drives, though not all, will briefly start the spindle motor upon detecting floppy insertion or door closing - this is to help seat the floppy centered. Motor should stop after at most 10s or so. And heads should not be banging the end of travel limiters. If you get this automatic action it's a very good sign, means the electronics part is not completly dead.