How do I Repair Intermittent Crackle

[Perkinsman]

I have a Hot Rod Deluxe that has an intermittent static/crackle type noise that I can’t locate. It seems to happen only when the amp is warmed up but it doesn’t happen all the time. Sometimes I can play it for hours without a problem & sometimes it will crackle after 15 minutes.

[Mick Bailey]

Cracking around the tube socket solder joints is the main cause of this problem. Discharge the amp, and take a look closely at each pin - often there are visible circular cracks around several pins. Sometimes when they're just beginning to break up it isn't so obvious. I usually resolder them all on an amp I haven't previously had in for repair as part of my servicing routine with these amps. Usually unrelated, but while you have the back off also check if it has the grey Illinois caps still fitted and look for a yellow/brown crusty discharge between the rubber seal and where the positive lead exits. This is a sign that the cap is on it's way out, and the rest to follow.

[Jazz P Bass]

You could try running a patch cord from the Send to the Return jacks.
If the Return jack is dirty that could cause issues.

[Jon Snell]

My guess without seeing it is a noisy valve, probably an output valve if the volume control has no effect. The grids work loose in the mica guides and movement makes the sound in some cases or a bad internal connection within the glass envelope.