On Sun, 7 May 2017 10:19:45 -0000 (UTC), Cursitor Doom
wrote:
I was winding up one of my old HP spectrum analysers (my best one, as it
happens, been sitting around unused for years)
Model number? I couldn't tell from the photos.
My guess(tm) is the big electrolytic filter cazapitors are shorted,
causing something between the line cord and the caps to smoke. Smoke
usually means some resistive device burning up, although it can be a
hot trace scorching the PCB. The color of the smoke would be helpful.
Black is carbon comp or oil, white is plastic wire insulation, gray is
phenolic, brown is epoxy or a dead mouse or insect infestation. There
are smells associated with each one that is recognizable. I had a
mouse take up residence inside an HP sweep generator last fall the
demonstrated gray smoke and a horrible stench. If you can't find the
source of the smoke or smell, shove one end of a 1/4" ID vinyl hose up
your nose, and inhale while moving the other end of the hose all over
the device. (Yes, I actually do this). It takes some practice and
fortitude. For a mouse, have a vomit receptacle handy. You won't
find any of this in books on electronic repair.
If you're dealing with very small amounts of smoke, that's either
invisible, or pervasive (smoke everywhere), I suggest one of these
airborne particulate detectors:
http://802.11junk.com/jeffl/Nikken%201394%20Air%20Quality%20Monitor/Nikken-AQM.jpg
http://802.11junk.com/jeffl/Nikken%201394%20Air%20Quality%20Monitor/
My office was filled with smoke when I arrived one day and I had no
idea where it was coming from. The Nikken "air quality" detector
found it fairly quickly.
If you have money, consider buying an IR camera. By IR, I mean heat
as in far-IR, not the common digital camera which does near-IR. Prices
are coming down and you get something reasonable that plugs into an
Android smartphone or iPhone. If you have a source of heat causing
problems, that will find it. I borrow one from a friend occasionally.
I've used one with great success isolating a bank of stepper motor
controllers with conveniently exposed power transistors. It was easy
to distinguish between warm normal, too hot, and stone cold.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558