Author Topic: No sound coming from my first attempt at Axis Fuzz  (Read 1033 times)

Electron Tornado

Re: No sound coming from my first attempt at Axis Fuzz
« Reply #20 on: October 09, 2020, 10:19:09 PM »

Perhaps I just simply chose the wrong pedal to make.

This is a simple circuit, don't give up!

Post some photos of the solder side, making sure the image is clear and that all your off-board connections are easy to see.
"Corn meal, gun powder, ham hocks, and guitar strings"

Who is John Galt?


Re: No sound coming from my first attempt at Axis Fuzz
« Reply #21 on: October 10, 2020, 07:01:36 AM »
Thank you everyone for the encouragement!

Here are the pictures.

I soldered in the 220 ohm resistor and 1nF cap, which was recommended by the original schematic to omit, to see whether if it would improve my tone but didn't help haha


I also measured the voltage of each transistor with the new battery.

Battery: 9.88v

2N3906 (264 hFE)
e: 4.54
b: 3.81
c: 4.12

2N3904 (260 hFE)
e: 3.69
b: 4.10
c: 6.57


Re: No sound coming from my first attempt at Axis Fuzz
« Reply #22 on: October 10, 2020, 08:57:50 AM »
Some easy learnings for audio transistor DC voltages.... (Silicon like the ones you have).
You want the base to be about 0.7v different from the emitter.
If the emitter or collector are connected to the rest of the circuit by resistors, you won't expect to read either 0v or  supply voltage on them. In amplifiers, collector volts are usually expected to be near half of supply volts (4.5v for us lot).
If it's NPN (2n3904), the base will be higher than the emitter. If PNP (2N3906), the base will be lower than the emitter.

So from the last voltages posted, the 2N3906 looks workable, but the 2N3904 is starved (base emiiter not forward biased enough). Consequently, the collector voltage is too high.
You also post Hfe measured that is believable for those parts, so we can assume you know which way around the ebc pins are.

As Duckarse spotted, those pot connections are not good. If you have flat side flush wire cutters, I would crop the wires close in rather than risk damage by unsoldering. While the wires are off, use the meter on resistance to confirm the pots are ok. Remake the wires by a short wrap around the pot legs before soldering.

Use the meter on resistance (or audible beeper if it has one for basic continuity proving) to confirm strip board track cuts and isolation between adjacent tracks. Use the schematic to show you what connects to what and just as important, what shouldn't connect. Confirm resistor values as it's easy to misread colour codes. You probably can't easily measure capacitors, but you can at least check that none have a short circuit.
Don't do resistance/continuity tests with the power on the circuit! Much of this can be done before you even wire the board up or apply power.

Finally, your basic workmanship is good & neat, so don't give up. You should be able to produce working pedals.

Croeso i Diystompboxes.

If they didn't hear you then you didn't say it.