Champ Clone?

[ca7922303]

So you have weak output. Looks like there is a 6V6 and 12AX7 in there, just like a Champ. All heaters are lit up?
Measure DC volts at 6V6 pins 3, 4, 8. At 12AX7 pins 1, 3, 6, 8.

6V6 pin#3(287v) pin#4(243v) pin#8(12v)
12AX7 pin#1(150v) pin#3(1v) pin#6(-5mv) pin#8(-1mv).

[Enzo]

The pin 6 side of the 12AX7 is not running. Look closely at the tube, are BOTH little haters glowing inside? Otherwise the the resistor connected to pin 6 might be open.

[nosaj]

Ohh the haters.......

nosaj

[Enzo]

Hey, I am a year older now, I make more mistakes.

[ca7922303]

The pin 6 side of the 12AX7 is not running. Look closely at the tube, are BOTH little haters glowing inside? Otherwise the the resistor connected to pin 6 might be open.

Both sides of 12AX7 are lit. I took the 6V6 to an amp shop near Nashville today and it tested at only 70%. Put an almost new 6L6 in and voltage readings are: #3(278v) #4(237v) #8(16v). The 12AX7 is a Jan Sylvania and tested @ 72%. Installed a JJ 12AX7 and readings are 1(225v), 3(0.2mv), 6(-1.3mv), #8(-9.5mv).

[Enzo]

OK, well th problem at hand is the pin 6 side of the 12AX7 is not running. If the heaters are both on inside it, then the plate voltage is missing. None of this has anything to do with the 6V6. Besides, whatever 70% means, the amp would be making sound with it. Swapping the 12AX7 won't bring back the missing voltage.

You even quoted me already, check out the plate load resistor connected to pin 6 of the 12AX7. Notice pin 1 plate has 200 volts and in 6 has none?

[ca7922303]

OK, well th problem at hand is the pin 6 side of the 12AX7 is not running. If the heaters are both on inside it, then the plate voltage is missing. None of this has anything to do with the 6V6. Besides, whatever 70% means, the amp would be making sound with it. Swapping the 12AX7 won't bring back the missing voltage.

You even quoted me already, check out the plate load resistor connected to pin 6 of the 12AX7. Notice pin 1 plate has 200 volts and in 6 has none?

What should #6 be?

[Enzo]

Not zero. Like you have 225v on pin 1. If it had been 198 or 253, those would work too. What we don't want to see is zero. That means no voltage is in there. What we also don't want to see is super high voltage, meaning unloaded power supply.. The amp will function, however well or poorly at a wide range of voltages. SO to me maybe 130 to 250v? But then some circuits only run at 90v. Point is, most any middling voltage will cause the tube to at least function. Right now with zero on that plate, that tube can't function at all. Well unless in your amp that section wasn't even used or wired in. But on a Champ, both halves ARE used. So we are not looking at this point for anything precision. At least in my mind ALL I am trying to determine is why that triode is not running.

[ca7922303]

Not zero. Like you have 225v on pin 1. If it had been 198 or 253, those would work too. What we don't want to see is zero. That means no voltage is in there. What we also don't want to see is super high voltage, meaning unloaded power supply.. The amp will function, however well or poorly at a wide range of voltages. SO to me maybe 130 to 250v? But then some circuits only run at 90v. Point is, most any middling voltage will cause the tube to at least function. Right now with zero on that plate, that tube can't function at all. Well unless in your amp that section wasn't even used or wired in. But on a Champ, both halves ARE used. So we are not looking at this point for anything precision. At least in my mind ALL I am trying to determine is why that triode is not running.

What can I do to figure out why pin#6 is zero. Pin#6 is wired directly to volume pot. Only wire going to board from volume pot appears to go to orange cap(.01T 400/10).

[loudthud]

That should be pin 7 that comes from the Volume pot. Check that you counted correctly.

Edit: Is it possible the amp never worked in it's present form ?

[ca7922303]

That should be pin 7 that comes from the Volume pot. Check that you counted correctly.

Edit: Is it possible the amp never worked in it's present form ?

Thanks for that, pin#6(136v), pin #8(1.3v). Amp does work, was pretty weak with ehx 6v6 and Jan Sylvania 12ax7 that's in it.