Re: Inendiary discs, was Tek 465 repair hints, svc manual? (fix story)


Miroslav Pokorni
 

I am curious how much of real visual effects (smoke and flames) did you get
out of that cap. I do not doubt that there was enough energy in the circuit
but a ceramic disc does not provide much of combustible material.

Personally, I have never had a good visual show. Had some stinkers (magnet
wire seems to produce long lasting stink), had power transistors (TO-220)
that exploded, but not much smoke and never any flames.

The first place where I worked when I got out of school was a former
government lab. People had lot of time at hand and a favorite stunt played
on rookies was to take a housing of an electrolytic and put in a piece of
resistive wire and a small spool of photographic film (in those days film
was still celluloid, a euphemism for nitrocellulose, an explosive actually),
put that contraption over a voltage in a Tektronix scope and have rookie do
something that required scope. Few minutes after power on, there would be a
burst of flame and smoke. Poor guy would quickly snap power switch off and
start warring how to fix damage. And that is when fun started: some guys
would offer to arrange for an installment payment for scope (what would take
10 years with price of scope in early 60s and low salaries in Yugoslavia),
some others would offer to find a guy who can fix the scope (at an
exorbitant price) and game was played until end of day.

Fortunately for me, by time I was hired, the enterprise became commercial
and people had to do some work rather than play pranks, but I heard stories
and 'victims' were pointed, some of them were in management by that time.

Regards

Miroslav Pokorni

----- Original Message -----
From: "Craig Sawyers" <c.sawyers@tech-enterprise.com>
To: <TekScopes@yahoogroups.com>
Sent: Tuesday, February 18, 2003 1:58 AM
Subject: [TekScopes] Inendiary discs, was Tek 465 repair hints, svc manual?
(fix story)


Like a 3 volt p-p signal riding on 6 volts of DC
with a .01
50 volt disc. Where did my signal go? Took the cap out and measures 4
ohms. No stress there but the cap failed. So it dont suprise me
either,
but its not the first thing I go looking for either.
One evening, listening to the Television sound through a stereo amp (50W)
and speakers the amp died - smoke and flames. Took the lid off, and all
that had happened was a 0.1uF disc ceramic decoupler had gone short and
crowbarred the power supply. There was enough energy in the smoothing
caps
to incinerate it after the fuse had blown (around 20J).

Craig

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