Sandspur Fuzz no sound

[skymaster747]

I build a Sandspur Fuzz everything looks find, and I test all the components before, installed.
When the pedal is bypass, the sound is normal, now when you engage the pedal there is no sound . Here are some pictures of the pedal in question thx

 

[skymaster747]

Ok I set the multimeter in V auto. Apply power to the circuit use the black lead to the PCB Ground and with the red Lead I touch the bottom of each leg

 

[Big Monk]

Ok I set the multimeter in V auto. Apply power to the circuit use the black lead to the PCB Ground and with the red Lead I touch the bottom of each leg

Ok. Now we are getting somewhere!




Take voltage readings at these points and report those.

Your transistors are not showing the expected voltages for this circuit. Did you keep heat on them for a long time?

 

[skymaster747]

No I didn’t heat them up I was quick. Those measure 1k and 33k. I got 2 extras that are new just in case

 

[Big Monk]

No I didn’t heat them up I was quick. Those measure 1k and 33k. I got 2 extras that are new just in case

I meant to measure voltage at those points. I want to see what voltage is making it to the collector resistors. Also, measure voltage coming in from the power supply:

 

[Big Monk]

Ok. I think now I did it right look this is the results I got

I would expect the collector voltages for Q1 to be around 1.3 v and Q2 at around 6 v.

Is the LED powering up? Do the voltages on Q2 change if you change the internal bias and Sundial control?

 

[skymaster747]

Ok this is correct .

 

[Coda]

Have you adjusted the trimmers at all?

 

[skymaster747]

Q1 are E=0 / B=0.241V / C=0.843V
Q2 Are E=0.244V / B=0.843V / C= 0.274V
The 33K=8.43V
The 1K =0.0V
The power input = 9.51V

 

[skymaster747]

Have you adjusted the trimmers at all?

Ten trimm pots ? They are in the middle

 

[Coda]

Turn the bottom one all the way to the right and then measure the voltage of the collector of Q3 (black probe goes to ground).

 

[Big Monk]

Ok this is correct .

Does your LED light up?

As @Coda said, try turning the trimmer up and see if it changes the Q2 voltage.

 

[skymaster747]

Yeah my LED function normally

 

[Big Monk]

Yeah my LED function normally

If you turn the Sun Dial knob and the internal trimmer knob all the way to the right, what is the collector voltage on Q2?

 

[skymaster747]

I see that the emitter in Q1 reads Zero

 

[skymaster747]

The colector In the Q2 is 0.274V

 

[Big Monk]

The colector In the Q2 is 0.274V

What about when you turn the bias knobs all the way to the right?

 

[skymaster747]

The same

 

[Big Monk]

The same

Try reflowing all the joints from the power rail to the transistor. If that does not get normal voltage to the collector of Q2, then it’s shot.

 

[Mcknib]

Are you using a battery snap it's difficult to see but looks like you've got 3 wires to your DC jack where are they wired to

What voltage do you get to the pcb

 

[skymaster747]

Yeah I have a batterie snap .
The voltage into the PCB is 9.51V