A tale of woe, including carelessness, stupidity and laziness....

Jay Jaeger cube1 at charter.net
Sat Aug 22 14:41:36 CDT 2015

On 8/22/2015 12:55 PM, Tapley, Mark wrote:

> Jay,
> 	this is a really great post. I feel really bad for you - having the same piece of equipment go bang/flash more than once would have been totally demoralizing to me - but I really admire both your tenacity and your willingness to share this with the rest of us. 
> 	Thank you! Sure hope that disk is spinning its proper string of bits before long. You deserve the chance to post a victory story soon!
> 										- Mark

Thanks.  Really, such mistakes aren't too demoralizing if one can get
the parts, get them in a reasonable amount of time, at a reasonable
price, and have the skill to do the fix (which, in this case, wasn't a
whole lot) -- especially if there are good lessons to be learned along
the way.

But the carelessness was DANGEROUS, which is really why I posted it.

(BTW, in the way of other stories, a good friend once took out the
processor UNIBUS interface and damaged peripherals when his watch
shorted to the backplane of a PDP-11/20.  I also did something not too
dissimilar with my ring shorting out one bus line on my PDP-8/L.  Sigh).

Unfortunately, bearings did not help the floppy drive, so now I am busy
taking the floppy power supply I got with my FD 100-8, making sure it is
up to spec to use with the Shugart (and correcting that if needs be),
and making it safer (mains fuse, switch) and more fault tolerant (fuse
in the 24V line, at least) and making sure all of the mains connected
innards are not exposed.  Just about done with that.  The +24V and -7 to
-16V are in spec, but the +5V (which, curiously for a 1A supply, does
NOT use a simple 3 terminal regulator) is a tad high, at 5.35V.  I may
just change it to use a three terminal unit.

Once I get that together, I can try out my SA-801's to see if that was
what blew the Altos power supply up, or if it just shorted against
something when I started that test.  I can also more easily then measure
the "wobble" on the SA-800 and compare it to other drives, swap out
spindles, etc.


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