Hum Problem- Off Topic

[Carl C. Miller Jr]

Hi All,

I picked up a Knight R-55A receiver recently and it has a serious hum
problem. The hum is not controlled by the volume control and it is very
loud. I thought this was a simple matter of replacing the power supply
filter capacitors, but after subbing in two different sets of caps, no
change. I changed the rectifier tube just in case, no change. I subbed for
the other tubes, no change. I checked and tightened the ground connections,
no change. I looked for shorted parts, bad connections etc. and found none.
All voltages are within tolerance. The only thing I can see that might cause
a problem is that the original builder did not believe in using the shortest
lead lengths possible. There is a veritable forest of components on very
long leads. This receiver uses point to point wiring. Could it be that these
extra long leads are picking up hum? or am I missing something else? I
noticed that moving some of them around, especially those connected with the
audio section, changes the pitch or tone of the hum.
Sorry for the off topic post,
73's
Carl KA5KAB

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