Path: utzoo!attcan!uunet!husc6!ukma!mailrus!iuvax!silver!commgrp
From: commgrp@silver.bacs.indiana.edu
Newsgroups: sci.electronics
Subject: Re: Tandon disk drives lose upper head
Message-ID: <7200012@silver>
Date: 28 Sep 88 19:46:00 GMT
References: <718@pedsga.UUCP>
Organization: Indiana University CSCI, Bloomington
Lines: 34
Nf-ID: #R:pedsga.UUCP:-71800:silver:7200012:000:1439
Nf-From: silver.bacs.indiana.edu!commgrp    Sep 28 14:46:00 1988




>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