On Jan 5, 2025, at 06:34 , James via groups.io <james@...> wrote:
The issue is that almost immediately there is a slight ticking noise inside the PSU. It starts as a fairly regular tick (every second or two) but after ten or twenty minutes has become more of a quiet crackling noise.
Are you sure it's in the PSU? Does it change if you bump the HV lead? I've had a tic from my 7704A that sounds like a static crackle if I move the HV lead with a nonconductive tool. Have not been able to make that go away.
I have a 7904 that's a bit older than yours, and IIRC it had a crackle that went away after disconnecting the CRT anode connector, shorting it to the frame, cleaning it, and applying some silicone grease. It still has a PSU tick when starting, but I understand this is common.
Adam
