5.25" floppy drive issues

[PgrAm]

I have been having some issues with the Teac 1.2MB 5.25" drive in my AST premium/286 PC. When I first got the machine about 2 days ago it seemed to function properly but after being used, it slowly became less reliable until at this point it can read the directory listing from most factory disks but fails to read most files. My first thought was dirty heads so I cleaned them to no avail. I then thought it might be the ribbon cables so I replaced them with known good cables with no success. I then tried to check the alignment with ImageDisk using an original IBM disk in the drive as well as some game disks and imageDisk appeared to get a good signal from all the tracks. The drive will correctly format 1.2MB disks which can then be read in all my other drives but not vice versa, using a different 1.2 MB drive in the PC will read all disks properly. At this point I'm at a loss of what to do, perhaps somebody could give me a clue on what I can do to fix this drive?

 

[krebizfan]

What model Teac drive is it? The maintenance manuals have a lot of suggested test points to check for proper operation. Well, if you have an oscilloscope.

My guesses are either the drive is partially out of alignment or something in the read circuit is not working correctly. Fill a 1.2 MB disk with data on the TEAC. If the TEAC drive can't read back all the data on a disk it wrote, that suggests a problem in the read circuit.

 

[PgrAm]

Thanks, its a TEAC FD-55GFR.

I do have a scope, a kikusui 30mhz model, although I think I've fixed the drive. I didn't realize that both heads could be aligned differently and that the main adjustment moved both at the same time. My guess is that part of the mechanism bent slightly while I was moving the machine, I was able to fix it by loosening the head mechanism and shifting it slightly while watching the imageDisk readout.

 

[zombienerd]

To me, it sounds like it needs some electrolytic caps replaced.