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Floppy drive problems

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dongfeng

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I have three full-height 360kB floppy disk drives, and all of them seem to have a problem.

The first drive is a 1985 Tandon with IBM logo. This one used to work, but rather intermittant, however now it does not work at all. Originally it was the drive from my dead XT. When an attempt to access it is made, it states:

SECTOR NOT FOUND ERROR READING DRIVE A
Abort Retry Ignore?

The second is a 1984 Tandon with IBM logo. I never managed to get this one working, it was the primary drive in my second 5150. When accessed in DOS, it says:

DISK ERROR READING DRIVE A
Abort Retry Ignore?

The third is a Magnetic Peripherals drive, but without an IBM logo as it was out of a clone. I have no idea how to set this drive up properly, anyone have a guide?

On both Tandons I have run them through a cleaning diskette several times, and also made sure that the T-RES is correctly set depending on the drive. I have also set the dip switches correctly in the computers and tried the drives in two 5150's.

Any idea if I can get them working again?
 
You should be able to get both working again but you'll need to check alignment and drive speed and hope that's where the problem lies (as opposed to an electronic problem that may be harder to diagnose.)

You'll need an alignment disk and associated software or a 'scope.
 
Maybe connectors from PSU are too wide?
You know what I mean?

I mean these four round pieces of metal in plastic connector ;).
 
Thanks for the replies! Sadly I don't have an oscilloscope, but I guess it could be a good excuse to get one! Any easier ways to check the alignment? I've checked all of the connections, and they do seem to be fine, as well as running the drives through the disk cleaning kit.

I also checked the Magnetic Peripherials drive and it is dated week 25, 1982 - I guess it could be a single sided drive, but it still doesn't like single-sided disks.
 
You tried standart DD double-sided disks?
They are just the same as single-sided disks, but d-sided ;).

Of course you'll need to format disk 'format x: /1'.

Single sided disks could not work, because many of them is too old to work.
 
dongfeng said:
I have three full-height 360kB floppy disk drives, and all of them seem to have a problem.

The first drive is a 1985 Tandon with IBM logo. This one used to work, but rather intermittant, however now it does not work at all. Originally it was the drive from my dead XT. When an attempt to access it is made, it states:

SECTOR NOT FOUND ERROR READING DRIVE A
Abort Retry Ignore?

The second is a 1984 Tandon with IBM logo. I never managed to get this one working, it was the primary drive in my second 5150. When accessed in DOS, it says:

DISK ERROR READING DRIVE A
Abort Retry Ignore?

The third is a Magnetic Peripherals drive, but without an IBM logo as it was out of a clone. I have no idea how to set this drive up properly, anyone have a guide?

On both Tandons I have run them through a cleaning diskette several times, and also made sure that the T-RES is correctly set depending on the drive. I have also set the dip switches correctly in the computers and tried the drives in two 5150's.

Any idea if I can get them working again?
Click to expand...
You may not need any tools other than a small slotted screwdriver & fluorescent light! Position the drive so you can see the marked spindle on the underside, but still attached to everything. When the drive tries to access a scratch floppy, adjust the potentiometer slightly until the bars (by your location, whether 50 or 60Hz on the electrical wiring) on the spindle don't move under the fluorescent lighting (several disk accesses may be needed).
The old full-height Tandon drives could be real picky. Never throw out the parts. Leave them for swapping parts to get as many drives as you have like this working.
 
Yep, I was remembering something like that. Of course, the one I had used a neon light but same idea. My marantz turntable uses the same trick, neon light even.
 
I thought I would update this thread after re-attempting a repair today :)

Out of the four dead FH drives, I have managed to fully revive two of them! I swapped the controller boards on the top of the Tandon drives around and noticed that one had a broken solder joint on a capacitor, the other a dry joint on the power connector. Re-soldered, ran a cleaning diskette through them and two perfect drives!

I've put them both in my second 5150, which is now working again perfectly! Just need a keyboard to complete it... ha ha

A third Tandon drive is partially working. It can read disks, and write to disks, and can even format. However, the format completes sucessfully, but then the disk cannot be read in any other drive. Formatting with a /s for system files results in the formatting error "Cannot find track 0" (or something along those lines). Any ideas?

I haven't yet tried to fix the Magnetic Peripherals drive.
 
sounds like the head stepper motor is out of adjustment.

In theory you need an alignment disk and an oscilloscope connected to a test-point which directly looks at the analogue signals coming from the head. and triggered from the index hole.
The alignment disk has 4 "whistles" on it, one positioned too far to the left, one a little left of centre, one a little right of centre, and one way right of centre.
The idea is to set the disk spinning with the head over the alignment track and try to get the picture on the scope symmetrical like "-iii-III-III-iii-" if you have
"-III-III-iii-iii-" then the head's too far out and you need to twist the motor right a bit, if it's "-iii-iii-III-III-" then it's too far the other way.

Now for the prob.... alignment disks are EXPENSIVE!

It Should be possible to do a rough setup using a scope on a known good disk, looking for the strongest signal, but it will be tricky.

Hope that's all right - it's been 20 years and I've only done it once or twice!
 
Boy, that's the OLD way of doing it.

During the late 80s when I opened my first repir company, after parting company with Radio Shack, we bought digital diagnostics from a couple of companies (J & M Systems Ltd. was one of them) that didn't require the use of a scope.

You'd just hook up a known good drive as A: and the target drive as B:, boot from the program diskette, insert the alignment diskette in B: and it would give you pretty little patterns to look at and align on.

They were pretty damn expensive then, but, the price of such items have probably come WAY down now.

I'm still using the various computer packages to this day to align IBM and non IBM floppy drives.

A search of the 'net will probably find something similar.
 
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