[Hallicrafters] SX-42 out of tolerance resistors

[David C. Hallam]

I think your conclusion is probably correct.  Circuit requirements and
resistor tolerances were typically rather broad.  A resistor drifting upward
in value would result in degradation of performance but generally not damage
to the circuit.  A shorted capacitor could cause major component failure.

David
KC2JD

-----Original Message-----
From: hallicrafters-bounces at mailman.qth.net
[mailto:hallicrafters-bounces at mailman.qth.net]On Behalf Of Julian Bunn
Sent: Monday, May 08, 2006 5:22 PM
To: Hallicrafters at mailman.qth.net
Subject: [Hallicrafters] SX-42 out of tolerance resistors


I'm just starting to look at the electrics of an SX-42. Recently I completed
an SX-62 which
is of course almost identical electrically. What I found in the SX-62 was
that the vast
majority of the carbon resistors over about 10K nominal value, were *way*
too high in
measured resistance. In some cases double, but nearly always 50% higher. I'm
finding the
same in the SX-42. For example, the 220K resistors in the audio circuit
measure upwards of
350K!

It seems to me that these old Hallicrafters need as least as much attention
to replacement
of the resistors as they do replacement of the capacitors. So why is there
so much emphasis
on replacing caps ... is it simply because when a cap fails it typically
shorts?

Julian





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