Post by jmpff3d on Nov 21, 2018 6:46:48 GMT
Though not strictly Herdware, this '1541-blast from the past' may make us appreciate our 1571s a little more ..
comp.sys.cbm #39804 (65 more)
From: mwandel@bnr.ca (Markus Wandel)
Subject: Re: help w/ 1541 error msg's
Date: Tue Feb 06 08:36:56 EST 1996
Organization: Bell-Northern Research Ltd.
Lines: 63
In article <4f6d0n$c2k@news-e2a.gnn.com>, X Nihilo <ExNihilo@gnn.com> wrote:
>Disk new command: 21 Read Error 20 6
>Open Write File: 74 Drive not ready 0 0 (the 2nd time I ran
>the program it said 21 Read Error 18 0).
>Open read file: 21 read error 18 0
>Scratch file: 21 R.E. 18 1
>Write Track 35: 21 R.E 35 0
>Write track 1: 21 R.E. 1 0 (2nd time it said 27 R.E. 1 0)
>Read track 35: 21 R.E. 3 5
>Read track 1: 20 R.E. 1 0(again, 2nd time was 27 R.E. 1 0)
My expert diagnosis based on this output is that the best way to maintain your
sanity is to drive to the nearest big bridge, and throw the 1541 off it.
If that doesn't work, throw yourself off it. These drives are trash.
Seriously, it's probably suffering from one of THREE major 1541 failure
modes:
1. The endless bashing the head against the track 0 stop on every format
and error has knocked something loose in the head stepping mechanism
and it won't maintain alignment any more (note: if there was just a
fixed misalignment it would work fine with disks it formatted itself.)
2. The woefully underdesigned power supply blew a rectifier. That's easy
to check... put a voltmeter across each of the big electrolytics in the
back of the circuit board, and verify one has about 10V the other about
21V. If either is low, one of the bridge rectifiers at the back
corner is probably blown. If that's the case you're lucky, substitute
a new rectifier and you're in business.
3. The disk isn't spinning reliably. Either it's slipping at the coupling
between the drive's hub and the disk's hole, or the belt is slipping.
Slipping belts can be cured with a product called "Rubber Renue"
available at better electronic parts stores. Slipping drive hubs --
I dunno, but you can CHECK for them -- if the disk appears to stop
rotating, push down on the door latch (or with the drive open, on the
part that the door latch pushes down) -- if it now rotates, that's where
the problem is.
I don't know about a fix for #1.
My first 1541 lasted about three years, then it started becoming flakey.
I could not fix it. What I did in the end was take a 360K half-height IBM PC
floppy drive, strip the analog electronics off and change all the connectors,
and bolt that into the 1541 chassis (which I had to modify too.) Some
experimental alignment later, I had a rock solid, direct drive 1541 which
has worked ever since. I may have been lucky to get the tracking right
(i.e. track 0 bash stop in the right place, stepper motor phased correctly,
read/write head compatible, etc.) All I know is that I can still read the
disks I made with that drive 8 years later.
The way I recently acquired a working 1541 was to find a flakey one for $5
that failed of something other than #1. It failed of #2, and I was able to
fix that, and now it's OK.
This is MY take on 1541s. Anyone else care to contribute theirs? I think
there should be a FAQ on these things.
--
Markus Wandel Ottawa Ont. Canada (613) 592-1225
markus@pinetree.org <-- NOT 'mwandel@bnr.ca' (that's for work only)
*** DISCLAIMER *** Not speaking for or representing my employer in any way.
