Hum Problem in a 69 Bandmaster Reverb

[SBax]

Trying to get this amp up and going from storage. Checked all tubes with known good ones, not an issue.
Hum is independant of volume. Here's a frequency snapshot. I'm looking for suggestions on where to start tracking down the problem. Thanks.


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[The Dude]

Best guess with an amp of that age is dried out filter caps. Check or replace all electrolytics.

[SBax]

Well, that was weird. The OT secondary was loose at the speaker jack. Soldered back and no hum.

[The Dude]

Well, that was weird. The OT secondary was loose at the speaker jack. Soldered back and no hum.

It's good to get an easy one every once in a while. Glad you found it!

[stokes]

Still a good idea to re-cap.Its an old amp and if it was unused (in storage) for a long time,those filters are over due.

[SBax]

Well, that was weird. The OT secondary was loose at the speaker jack. Soldered back and no hum.

That makes no sense based on the frequency scan that shows a 120 Hz and harmonics hum.

I had inspected the doghouse at the same time and replaced the cover but spun it around the other way. The foam strip pushed down a loose connection that was causing the hum. As I opened the doghouse cover again, the hum returned. That was fixed with a re-solder and now the real cause for the hum was fixed.