A friend of mine brought along a Fender 1972 Deluxe Reverb mit a noise problem which I tracked down to the PI and poweramp stage by pulling one tube after the other until I heard the noise just when just the PI tube and the powertubes are inserted. Now to the complicated stuff: The noise only occurs when the amp is running for 20 Minutes.
What I’m going to do as my next steps is the following:
- Clean all tube sockets of PI and Poweramp tube
- Cut the HT from the preceding stages, so that the PI Input is just connected to some wire and coupling caps at their Ends. In case this leads to no noise, I’ll find out which of the both stages produces the noise and Change the resistors with new ones. In case nothing happens and the noise persists, I’ll
- Change the cardboard under the cardboard with the components with a new one.
- I don’t know any further steps, but I’ll think about it
Some more ideas can be found in the gear page where Andy Fuchs was so kind to share his Top5 of fixes:
- Spray all controls, sockets and switches, tighten sockets where required. Don’t forget plugs to and from reverb pan and AT the reverb pan. Work the speaker cable in and out a few times to clean contacts.
- Reheat all tag board wire connections and/or dry out tag board with heat gun.
- Replace funky cardboard under tag board (often absorbs moisture and causes weird intermittants).
Lots of cool organic things growing on it from solder flux etc.
- Filter caps and/or tube replacement as required.
- Add silicone to wire leads on reverb pan.
I’m very curious what I’ll find out about the noise after I’ve found the source.