[sci.electronics] Tandon disk drives lose upper head

jeffj@pedsga.UUCP (09/26/88)

[spritzensparken!]

I have had two Tandon TM-848-02 floppy drives fail recently.
(half height DSDD 8")
Both failed the same way.
They worked as double sided, then the upper head failed.
Now they cannot read nor write the upper side,
but function okay as single sided.

The heads look fine.
What went wrong?  Can I fix it easily and cheaply?
(Remember that new drives are $50 at computer fairs).

Thanks for your assistance.


Jeffrey Jonas

allegra!io!mtune!petsd!pedsga!jeffj
decvax!mcnc!rutgers!petsd!pedsga!jeffj

commgrp@silver.bacs.indiana.edu (09/29/88)

>I have had two Tandon TM-848-02 floppy drives fail recently. (half 
>height DSDD 8") Both failed the same way. They worked as double sided,
>then the upper head failed. Now they cannot read nor write the upper 
>side, but function okay as single sided.
>The heads look fine. What went wrong?  Can I fix it easily and 
>cheaply? (Remember that new drives are $50 at computer fairs).
>
>Jeffrey Jonas

Upper head failure is common on all floppy drives. Unlike the lower 
head, the upper head is mounted on a delicate suspension.  Sometimes 
they fail for no apparent reason; the most common failure mode is the 
upper head being torn away because someone put a disk with a warped 
jacket into the drive, or because a technogeek interpreted the message 
"Put a write-protect tab _ON_ the disk" literally.  :^(

It's not economical to replace the heads; new heads cost almost as 
much as a whole new drive, and a good bit of labor is involved in 
realigning a new head, even if you have all the right equipment (test 
set, analog alignment disk, oscilloscope).

I have been able to salvage a few drives with bad upper heads: 
Carefully inspect the solder joints where the cable connects to the 
flat flexible printed-circuit leading to the actual head. The wires 
often break here, and the break may not be obvious until you disturb 
the wire.  Broken wires can be resoldered, using a very small tip.

--

Frank
reid@gold.bacs.indiana.edu