11-01-2018, 08:03 AM
Start with cleaning tube sockets. See if all screws holding chassis together are tight.
See if any ground posts that are riveted have good GND connection, tap them with something plastic, see if it affects anything.
check your caps, especially the AC power filter (if present) for cold soldering spots.
And, as the last resort, change tubes one by one.
(all above applies if you are sure that it is gone after 20 minutes and not because some fluorescent lamp is there producing noise)
See if any ground posts that are riveted have good GND connection, tap them with something plastic, see if it affects anything.
check your caps, especially the AC power filter (if present) for cold soldering spots.
And, as the last resort, change tubes one by one.
(all above applies if you are sure that it is gone after 20 minutes and not because some fluorescent lamp is there producing noise)
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
![[-]](https://philcoradio.com/phorum/images/bootbb/collapse.png "[-]")
