Sandspur Fuzz No Effect, Low Q2 Voltage

[DSoda]

Hi everyone, relatively new to building pedals. I've once built an Electra distortion but that was a fluke as my next builds have never made a sound.

Here's my latest attempt which I thought would make an effect but I only get the true bypass sound. It's a Sandspur Fuzz with BC183Ls.

Observations:

1. No sound when effect is engaged.
2. LED turns on when effect is engaged
3. True bypass works. There is sound that goes through the pedal when it is off.
4. Voltages through multimeter:

1. 9.5V of power coming from the top portion
2. R4 also near 9V
3. Q1 voltage at collector is 0.7
4. Q2 voltage at collector is 1.5
5. R3 voltage is 1.5

Note: Bias trim and Sundial were both set to full as suggested in the other thread. I noticed that when I turn the knobs down, the voltage goes up, but only slightly.

5. My soldering is pretty bad. I had much cleaner joints in the past. I don't want to blame my equipment but the tip may need replacing. The solder is starting to ball up already.


Please let me know what I can do to salvage this project. I would really love to get this to work.

 

[Coda]

Transistor orientation. Your transistors are ECB, and the PCB layout is EBC, left to right. Just twist the center leg to the right side, and that right side leg to the center. Make sure they aren’t touching…

 

[DSoda]

Transistor orientation. Your transistors are ECB, and the PCB layout is EBC, left to right. Just twist the center leg to the right side, and that right side leg to the center. Make sure they aren’t touching…

Thank you! I moved the legs over and now I'm getting 9.3V on the collector legs of both Q1 and Q2. I noticed that my bias trim and bias knob both do not work. No matter where I move the knob, the bias remains the same.

Also, there is still no fuzz sound coming out when the pedal is engaged. I still have my bypass, LED still works when pedal is engaged. There is no sound at all when the effect is turned on.


***Changes made as of today: moved legs of BC183L and now I have higher voltages on the collector legs***

 

[Laundryroom David]

Thank you! I moved the legs over and now I'm getting 9.3V on the collector legs of both Q1 and Q2. I noticed that my bias trim and bias knob both do not work. No matter where I move the knob, the bias remains the same.

Also, there is still no fuzz sound coming out when the pedal is engaged. I still have my bypass, LED still works when pedal is engaged. There is no sound at all when the effect is turned on.


***Changes made as of today: moved legs of BC183L and now I have higher voltages on the collector legs***

I would do a close visual inspection - are all component values correct?

I would then used a clean and well-tinned tip in the iron and reflow all the solder joints. You have a lot of solder joints and, as you recognized, they need some help to do their job properly. If you need to replace any components, might as well do so while the iron’s hot as well.

Off board wiring - nothing wrong with doing so, but you double the # of solder joints per potentiometer when you do off board vs pcb mount pots. You might want to consider using pcb mount pots for next time if you can.

Once you’ve confirmed your component values and reflowed the solder joints, please try the pedal again. If it still doesn’t work, then onward to continuity tests and audio probing methinks.

 

[DSoda]

All component values are correct upon double checking last time. I will triple check but that part seems to be in order.

I will go out and buy a new tip as my old one seems to have given up on me. I use a decent iron but I think my upkeep has been shoddy.

Unfortunately I couldn't find a C1K that was board mounted from Tayda. I live in Asia and they're the easiest supplier for me to get from. I was able to get a few C1Ks from stompboxparts since I needed to repair a fuzz face I already own anyway. I will go for board mount pots in my next build.

I will try reflowing things when I get a new tip. I will also go do more continuity tests and audio probing. The probing bit is new to me but looks like it will be necessary. What should I hear when I probe?

Also, I would still love to hear suggestions from others on how I can fix this.

Thank you very much for your response, David.

 

[Laundryroom David]

Post in thread 'Noob Audio Probe question'
https://forum.pedalpcb.com/threads/noob-audio-probe-question.18062/post-216713

 

[DSoda]

***ACTIONS DONE TODAY***

1. Audio probe found the ff:

1. Clean trim, C1, Q1, R2 - with sound
2. R4 onwards - no sound
3. R1 - no sound

2. Continuity in pedal is still in order. It receives power throughout.
3. New tip ordered for further soldering.

If R4 and R1 both don't have signal, what does that mean and what do I do moving forward?