[Boatanchors] carbon comp resistors failure mode?

[J. Forster]

Unlikely, IMO. Put a DMM across it and see or try a heat gun or freeze spray.
-John


> Hello all,
>
>
>
> I am trying to troubleshoot some odd behavior in a bias supply/keying
> circuit of an amp.  I am trying to figure out why the bias supply slowly
> becomes less negative as the system warms up when it should not. This is
> causing the finals to begin conducting when they should be in cutoff even
> though the system isn't keyed!
>
>
>
> It is quite a complicated little system, but I was thinking that one
> possible cause of this could be a bad resistor.  There is a 2W carbon
> composition resistor in such a place in the circuit as to be suspect.
>
>
>
> But the question is, is it a common failure mode for a carbon comp to
> LOWER
> in value as it warms up? Has anyone seen that behavior? Or should I bark
> up
> another tree?
>
>
>
> Thanks
>
> Eugene w2hx
>
>
>
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