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Greetings, BYOC forum. I recently finished building the Classic Fuzz pedal. It’s not working correctly.

The good:

⁃ I have sound
⁃ I have an LED.
⁃ Bypass works.
⁃ All the dials and switches work.

The bad:

⁃ Sounds crappy. Tapers off terrible, fizzy and broken sounding. Hard to explain.
⁃ Output is low; unity volume is around 3/4 on the volume dial.

When I was building the pedal, I put all the film capacitors in the wrong spots (didn’t realize they were all different!). I removed them with a de-soldering pump, put them in the right spots.

Everything else was smooth sailing, all things considered. I had soldered before, but never on a circuit board.

Here’s a pic of what I ended up with. How do I diagnose what’s wrong?

https://pasteboard.co/K0SplYh.png

Thanks!
Adam

Do you have access to a multimeter and know how to measure DC voltage with one?

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Sure do!

OK, cool. Suggest that you check the voltage bias on the collector (leftmost leg) of Q2, the upper transistor. What you describe sounds like the output tone when this transistor isn't correctly voltage-biased.

Please take three voltage readings on the collector, varying the setting of the Bias control pot, and report those results here:

• Full CCW
• At the midpoint
• Full CW

NOTE: Moving this thread to the "Transistor based Distortions, fuzzes, etc." forum where it properly belongs.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Okay. I measured each leg of the top transistor at each setting on the dial. Looking at it from left to right in the picture I included earlier, legs 2 and 3 remained constant at 1.25v and .65v (there was actually a slight variation, maybe 100th of a volt). Leg one changed:

CCW: 0.66v
M: 2.61v
CW: 6.01v

CCW = the position while looking down on the pedal as if it was being used on a pedalboard.

Voltage at the source is 9.36v.

Thanks!
Adam

Edit: readings were taken with a cable inserted into the input jack. The led is not lit with the cable unplugged.

Those voltages look very reasonable. I like to run the Bias control on my own CF so that the Q2 collector is in the 5.5 - 6.0V range, so I'd expect the your pedal to sound good with the bias dialed almost all the way up. If it's still sounding fizzy/sputtery and not sustaining smoothly at that setting, it suggests the problem is somewhere else in the circuit. Check the Q1 transistor leg voltages, too. E, B and C should run right about 0, 0.6, and 1.25V respectively. If those check out, I would try doing a full solder reflow per these instructions: viewtopic.php?f=9&t=52188

And while you have the PCB assembly out of the enclosure, taking a photo of the solder side of the board and posting it here could be useful in identifying the problem.


That is per design. The power source doesn't have the required connection to ground until the ring of the input jack contacts the sleeve of the input cable plug.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Thanks! I really appreciate all the help you’re providing. I’ll check all this out and let you know how it goes.

Best,
Adam

Voltages checked out on the other transistor. I’ll do a full reflow one night this week and report back. Thanks again.

It's pretty amazing how often we see a solder reflow clear up mysterious pedal problems like yours. But if the reflow doesn't do the trick, I would suggest replacing BOTH transistors. They are the component most likely to be at fault in an issue like this (assuming that it is a component problem). And there's no point in trying to guess which one is the culprit when the voltages all look good. So if this is the case, contact sales@buildyourownclone.com and request a new pair of transistors. They should be replaced at no cost, since the pedal has never performed correctly.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Thanks duhvoodooman. Quick question for you: is it normal/expected for unity volume (where the guitar is the same volume with the pedal on or off) to be at 75% of the level dial? For most fuzz/od pedals I have used it’s usually 25%~50%. Having said that, I have never played a real fuzz race before, so other pedals might not be a good comparison.

In other words, when I have the pedal on, I have to have the level at least 75% up. Below that, the guitar is quieter than when the pedal is bipassed.

No, that doesn't sound right. On my own CF, with the Q2 collector bias set between 5 - 6V and the Fuzz control at 3 o'clock (~80%), I get unity volume (bypassed = engaged) at 9 - 10 o'clock (20 - 30%) on the Level control. So I would assume that your lack of output volume is just another manifestation of the same problem.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Thanks, that's what I was expecting.

Solder reflow didn't help. I'll be emailing BYOC tomorrow. Thanks again for your help. I'll let you know what happens!

I ended up getting an entire “pink pack” from BYOC (I paid for it) - all the transistor, resistors, and caps. And PBC board. Put it together from scratch using the pots, jacks, etc from the first kit. Everything sounds great now! Thanks for all the help. I’ll definitely be building another BYOC pedal in the future. But first I’m building a JBL D130F cab.