@billy
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Could be something as simple as a dry solder joint Luigi
It’s just a process of elimination
Are your pins 2 and 15, 0 volts or do you get a small reading
Got the voltages from an old post from Petevig
Yours look to be ok in comparison
1– 1.34 16– 1.34
2– 0.69 15– 0.69
3– 3.56 14– 3.56
4– 3.58 13– 3.57
5– 4.75 12– 4.78
6– 0.00 11– 7.22
7– 4.75 10– 4.78
8– 3.56 9– 3.57
The only difference is your internal diode bias pins 2 and 15 are at 0 whether that would make a difference I don’t know
I use gimp for mine
If it’s on-board pots I use the guide in the build doc for measurements then always print it on paper or card to check it fits before committing to drilling
Basically it’s measure everything several times to make sure it all lines up and your labelling won’t be obscured by pots, washers etc
I usually use paper tape to draw horizontal and vertical centre lines to get it nicely centered and a square rule, digital caliper and centre punch and always drill 3mm pilot holes
The best men to answer this are Cybercow, Wilkie and Playsforfun all of whom have completed complex builds with lots or drilling also Chuck and Dan who’ve recently put up some nice builds
Do you have another to try I’m not 100% sure what voltage you should get with the IC in socket at pins 1 and 16 but I know it’s the current into those pins that drives the filter reading Tonmanns post here it does say it should be low signal
https://guitarpcb.webs.com/apps/forums/topics/show/8230458-swah-super-white
Hopefully someone with a working circuit can post IC voltages to see if it’s a problem
Another great looking pedal
Defo got the Chuck style I like the tb 11 looks almost like a code
Now is that a dragon fly or something else
Great looking beast Chuck
I really like the enclosure knobs, labelling and the countersunk LED
I may give your mods a go I think I’ve got a PUFF somewhere
Glad it’s sorted Steve
Just finished work and was about to have a look
If possible could you post your working voltages for IC1 and 2 just so I can add it to my notes, your problem would have been obvious checking resistor bands but not from the voltage to pin 2 the voltage looked good with the feedback from pin 1 so interesting to note that
Cheers
You can garner some info from your voltages Steve
You’ve got 7.24 going into pin 4 (power) 0 on pin 11 (ground) and all other pins with the exception of pin 14 (output) are around 3.62 half the power supply VB as they should be so that tells us your power section is ok
The voltage divider R29 and 30 is working providing VB, you’re getting 5v on Q2 and 3 collector so we know the regulator part is supplying VC
D3 is working it’s got what’s coming out of pin 14 less a little voltage drop through R24 then as expected with a germanium drops around 0.3v unfortunately not enough signal going into Q2 base through Q3 to provide the current required at pins 1 and 16 of the LM13700
So it’s just a case of a process of elimination which will hopefully lead you to the cause – wrong value, cold solder joint, faulty component etc etc
Post some nice clear images Steve your Q2 base voltage is too low it looks like it starts at pin 14 of the TL074
Did you check all your resistor values etc prior to installing them
Your voltages are confusing me a little Q3 emitter is at 4.05v with only 1.30v and 1.21v going to pins 1 and 16 of IC1
When you set the trimmer did you turn it in small increments
Try turning the sensitivity control fully off and using the bias trimmer as a manual sweepable filter to see if you get any wah sound
With D3 put your black probe to ground and measure the voltage both sides with your red probe it’s just to see what’s going in and what’s going out to Q2 base
Post voltages on all IC and transistor pins Luigi that may indicate your problem area
All your component values and orientation look correct
If I understand correctly you get clean signal in both bypass and effects position of the 3PDT? If that’s the case just swap your wires back on the socket end not the pcb end it’s much easier to remove and resolder on the socket lugs
The most recent problems with this circuit have been an incorrect trimmer value or a D9 series Russian germanium diode where some have the stripe on the anode + side
Check your trimmer is a 50K code 504 and post voltages on both sides of D3
It is fairly difficult to see all your component values clearly if you could post a photo of the component side with the wires moved out of the way as much as possible
You can check your transistor internal diodes with your meter Tim to see if it’s good or not
https://www.allaboutcircuits.com/textbook/semiconductors/chpt-4/meter-check-transistor-bjt/
Transistors can be damaged by heat from your iron you really only want to solder for 3 to 4 seconds you actually did the correct thing initially using a socket if you have another socket I’d recommend using that obviously be careful you don’t accidentally lift a solder pad again with you removing the socket your pads have been subjected to a bit of heat
When using sockets don’t solder the transistor pins in until you’re happy it all works I usually only solder 1 in to hold the transistor in place if you have a small croc clip use that as a heatsink by clipping it on up near the transistor body
The parts look correct from what I can see Tim
Reflow all your solder joints hold your iron on the joints for around 4 seconds until the solder flows
The joints on the bias pot look ball like and could be dry inside, this would affect your transistor biasing as you turn the bias pot the voltage to the transistor collector pin should change ( the outer pin without the small metal tag)
With this being a small circuit I’d reflow all joints
