About pittbull ultra lead

Amps & Cabs Ultra-Lead
1

Hello,My pittbull ultra lead has a malfunction and needs help to resolve it. clean channel is normal，but lead/rhythm channel is experiencing issues with very low volume. I have tried replacing all the tubes and still cannot solve the problem.May I ask if you could provide me with a circuit diagram so that I can repair it? Thank you very much！

Best Regards

Ziv Huang

2

Hey Ziv,

Sorry to hear about this and I think you did the right thing to change the tubes first.

We will work with reputable repair shops and give them information but we don’t send out schematics otherwise. Or you can send it in for a repair to Fryette?

Let me know what you prefer.

Regards

Dan

3

Hi dan
Thank you for your kindness, but it’s difficult for me to send it to you as it’s quite remote.May I ask you a question?

I used an oscilloscope to test V3A&B. The 8-pin output signal of V3 is normal, which means that the signal strength is normal before entering EQ control, at 470pf. The signal before the two 0.022uf capacitors is normal. However, after passing through these three capacitors, it is impossible to measure the signal on the EQ potentiometer, and of course, it is also impossible to measure the signal on the vol potentiometer. What are the situations that can cause the above problems？

Best regards

Ziv

4

Hi Ziv,

  • What’s the setting on your scope?
  • AC or DC coupled?
  • Assuming 1Meg impedance?
  • What is the input signal, magnitude and frequency?
  • What is the rotation of the pots you are measuring?

If the signal disappears could there be an open circuit? Or could that point be shunted to ground?

It is quite hard to debug like this!

Regards

Dan