[GreenKeys] Model 32/33 fires

[Jack]

I recall seeing a lot of 33 covers that had some kind of sprayed-on
white-ish
coating on the inside. It definitely was not there to cut down on the
noise!




-----Original Message-----
From: greenkeys-bounces at mailman.qth.net
[mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of Jim Haynes
Sent: Tuesday, February 07, 2012 7:07 PM
To: greenkeys at mailman.qth.net
Subject: [GreenKeys] Model 32/33 fires

I was talking with an ex-Teletype friend today, who mentioned a piece
in 
the Chicago Tribune yesterday about the occasion in 1967 when
McCormick
Place burned down.  The cause of the fire was never determined, but it
was thought to have originated in a booth at a trade show that was
about
to open.

Around that same time it was discovered that Model 32/33 machines
could
catch on fire.  It involved a certain kind of plastic used in the
distributor or selector which expanded and froze the shaft; and then
the motor lacked a thermal cutout or fuse and would get hot enough to
set the plastic cover on fire.  And the cover was somewhat
fire-retardant
but it would burn.

He didn't tell me what was done about it - presumably materials were 
chosen to prevent the problem and the motors were changed to be self-
protecting.  But so far as I know there was no general recall and 
replacement of the dangerous parts.

So, if you operate Model 32/33 machines, it's best never to leave them
unattended and turn them off when you aren't going to be present.

It can be a lot worse - I was reading yesterday in the AWA Journal
about
a man who had one of those Chinese-made clip-on fans operating, when
the
clip let go and the fan fell to the floor, blocking rotation.  And
then
it started a fire, which he arrived just in time to put out.  Most
motors
of that type are impedance protected, so they don't get dangerously
hot
even when stalled; but those Chinese companies tend to skimp on the
copper
and iron to the point where the motors are probably just short of
catching
fire when the fan is operating normally.


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