my latest problem…im trying to trace the signal. on the V1 (12ax7) I get a signal on the scope…when I move the probe from there to the junction of the 68k resistors to the input , the signal vanishes. ive checked and re-cheked and changed the components. still no signal …this amp doesnt seem to have a coupling cap . Is this correct. It has the 100k plate resistors going to b+4 and a 250pf cap going to the treble pot. i cant figure out what is wrong…please help Mike
Hello @mikecasey,
I’m not sure how to visualize “junction of the 68k resistors to the input.”
Please add a schematic.
Sincerely,
Aaron
Hello @mikecasey,
I see the schematic.
With regards to signal injection, are you using a 1/4" plug or a direct connection the junction of the resistors?
Note that the input jack will short the signal to ground.
No plug, no signal.
Sincerely,
Aaron
I’m sorry made a mistake….the signal comes out from the plate not the anode……
Correct, @mikecasey,
For this side, the signal enters on the control grid (pin 2 for this side) and exits on the plate (pin 1).
Sincerely,
Aaron
I believe I have the dog house wired wrong. I thought it looked fairly straight forward, but obviously not because it doesn’t work. I think that’s where the problem is. So I’ve hesitated to do this, but I have disconnected all the wires from the dog house. And labeled them according to the schematic. now I need someone with the time and the patience to help me wire it properly. If someone out can help me I would really appreciate it
Hello @mikecasey,
This will be challenging.
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Locate an image of an assembled amplifier. Verify your capacitors are correctly installed,
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Locate a schematic and very carefully follow each wire to the associated tube socket.
Best wishes,
Aaron