GVT52-212

[burnrecordings]

I recently purchased this combo and I love it!
However being ignorant to any issue it might cause, I had been switching the 25W/50W switch back and forth and I think I cause something to fail.
Would anyone know what It might be or where to start? I have a intermediate level of electronics experience. All fuses look fine and the amp powers up. The issue I'm having is no sound and it looks like two of the preamp tubes are not heating up as there is no glow. Switching the power does not change this. Anyone have any Ideas? Thanks in advance!

[Hangman]

The owners manual suggests that the amp should be on standby when you switch the power switch. its never a good idea to quickly switch it back and forth.
do the preamp tubes get hot? sometimes they don't look like they are glowing, but they are. the best way to know is if they get warm.

the HT fuse could have blown. they are often times hard to tell if they are blown or not. best to check with a continuity meter.

-steve

I recently purchased this combo and I love it!
However being ignorant to any issue it might cause, I had been switching the 25W/50W switch back and forth and I think I cause something to fail.
Would anyone know what It might be or where to start? I have a intermediate level of electronics experience. All fuses look fine and the amp powers up. The issue I'm having is no sound and it looks like two of the preamp tubes are not heating up as there is no glow. Switching the power does not change this. Anyone have any Ideas? Thanks in advance!

[Hangman]

just realized you addressed the preamp tubes being cold in your post, sorry about that.

If a few preamp tubes are not heating up, there could be problems with the DC filament supply. as I recall ampeg has DC filaments on a couple of the preamp tubes. that would seem unrelated to the switching of the power level though.

[burnrecordings]

I tested all 4 fuses and they check out. How would I check a DC filament supply?
Would photos help with this problem or are there any schematics I don't know about?
Just trying to save on a Tech bill if possible.

just realized you addressed the preamp tubes being cold in your post, sorry about that.

If a few preamp tubes are not heating up, there could be problems with the DC filament supply. as I recall ampeg has DC filaments on a couple of the preamp tubes. that would seem unrelated to the switching of the power level though.

[Hangman]

You could pull the chassis and measure the voltage between pins 9 and 4&5.

I'm attaching a picture from the GVT15 schematic that shows the DC filament circuit. I couldn't find a schematic for the GVT52. So things will be different on the GVT52 but they should be similar enough that you might be able to figure it out.
it seems unlikely that the rectifier would go out, but its not out of the realm of possibility.

switching the power mode may have sent a transient spike through the filaments and smoked the preamp tube filaments? hard to say.