Hey,
I'm working on this old Gallien Krueger guitar head I got with my brother from a storage unit we bought. We've sold basically everything else from the unit and have more than made the money back, so this thing's essentially free.
Symptoms are: no output, preamp out works great, but nothing from the power section.
Running through the signal chain and, while I'm new to diagnosing and fixing amps (only been doing it for 2 years, and mostly tube so far) I usually understand things pretty well, but I am having trouble testing part of the circuit. I'm trying to test voltage going into the output transformer, orange and green wires, from Q9 and Q10. I've been testing to chassis ground so far on everything else, but this time it arcs and pops through the output. Is this a symptom or am I testing incorrectly (totally possible.) I do not know what the voltage should be, but I suspect the OT is bad, so I am trying to test to make sure voltage is present going in.
I believe everything before this in the chain is testing good, but I could also be wrong about that as well, realistcally I'm still a novice.
Thanks for the help!
(https://drive.google.com/file/d/1Zm0nk767zVm-ZLgPm8Oz33WFZlwmHtX8/view?usp=drive_link)
Is this the schematic that you are working with?
Yeah that's the schematic, sorry I thought I had attached it, must have done it wrong.
If you are trying to measure at the OT primary while signal is applied the arcing and popping may be normal.
Have you checked and found signal everywhere before that, like at emitters of Q7, Q8? If not, do that first.
If so, try connecting meter with power off, then power up with no signal applied. Bring up signal very slowly to check voltage, stop if arcing or popping occurs again.