Champ with no sound

[jimmydweed]

Hello, just turned on my fender champ clone and I'm getting no sound at all from the speaker. I took a few measurements and seems that the fault is around the 6v6 power valve. Unfortunately I don't have another 6v6 to swap in and see if that's the problem.

Plate voltage: 326 V (Seems fine)
Grid/screen voltage: 179 V (Seems way too low)
Cathode voltage: 6.3 V (Should be around 18 V)

I did some calculations
Cathode current: 13mA (should be around 45mA)
Screen current: 13 mA (should be around 4mA)

Anybody knows what could be faulty? Thanks.

[Firestorm]

Low screen grid voltage will affect the cathode voltage, so that seems "right for the conditions. But it should still make some sound. Verify that the speaker is sound, that all connections are solid, no shorts, no burned components. Particularly check the values of the screen grid resistor (if you used one) and the dropping resistor feeding the screens. Check voltages with the output tube out.

If everything seems right, you'll need to swap in another tube. Unless your PT is undersized, it likely has a little heater current to spare, so you could briefly use a 6L6 to confirm that the 6V6 is at fault.

[martin manning]

Pull the power tube out and measure voltages. Plate and screen should be essentially the same, grid and cathode both zero. If so, then it's likely to be the the tube.

[jimmydweed]

Speaker works fine, slight noise when I measured plate voltage. Voltages with 6v6 removed.

Plate voltage: 351 V
Screen Voltage: 332 V

Grid Voltage: 0V
Cathode Voltage: 0V

So it seems like the tube is gone. Thanks for the quick replies and help.