Tagged: swah building help
January 2, 2021 at 12:00 pm #16486
I’m not new to pedal building but I’m new to this forum.
I am trying to build the swah pedal that I have bought from the musikdinge store. I have finished all the soldering of the components and have connected all the wires. However, I cannot get the wah effect when I try the pedal with my guitar and amp. I get a clean sound both with true by pass and when I switch to the wah effect. I have already checked that the input goes through the circuit only when I switch to the wah effect ( I press the 3DPT).
thank for the help.
Here are a few pictures of the pedal.January 2, 2021 at 1:08 pm #16488
thank for your answer.
i did what you suggested but now it doesn’t work at all (no TB no effect).
the lug you labeled as TIP is connected at the “small connector” the “mic” one, the other one is to the “long” (the positive) are you sure the “mic” should go to the input of the board?
thanks.January 2, 2021 at 1:22 pm #16489
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 possibleJanuary 4, 2021 at 10:29 am #16519
yes i get clean signal in both bypass and effect.
the trimmer is a 50k
d3 have a misure of .244V (good for a germanium) with the + and – show on the picture:
the voltage i measured, when i give 9v at the circuit, around d3 is 0.22v and -0.22v (if i invert my multimeters pointers)
here a more close photo with all components.
thank for your help.January 5, 2021 at 1:30 am #16523
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 correctJanuary 6, 2021 at 7:45 am #16533
here my measure (all in V):
D3) 5.13 on the negative 5.37 on the positive side
IC1) from 1 to 16 -> 1.30 0 3.74 3.73 4.93 0 4.93 3.72 3.73 4.93 7.46 4.92 3.71 3.71 0 1.21
IC2) from 1 to 14 -> 3.70 3.70 3.69 7.42 3.62 0 3.69 3.40 3.76 3.69 0 3.68 3.64 5.72
Q1) CBE -> 7.39 4.34 1.84
Q2) CBE -> 4.98 5.12 4.62
Q3) CBE -> 4.98 4.62 4.05
IC3) Out Ground Input -> 4.99 0 7.34January 6, 2021 at 7:33 pm #16537
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 soundJanuary 8, 2021 at 9:14 am #16566
yes i did with small increments.
i try to set SENS to 0 (RES and DECAY to middle) and the trimmer from 0 to max but i still don’t have any effect.
the measures i did last time was with SENS RES and DECAY to max and the trimmer on the middle.
new measure with SENS RES DECAY to middle and
trimmer to 0 :
IC1) pin1 and 16: 1.32
Q1) 7.19 4.25 1.79
Q2) 4.97 5.55 4.97
Q3) 4.97 4.97 4.35
D3) 5.55 5.68
trimmer to max:
IC1) pin1 and 16: 1.28
Q1) 7.28 4.28 1.81
Q2) 4.96 5.55 4.97
Q3) 4.97 4.96 4.35
D3) 5.55 5.68
it looks like that the trimmer makes no big difference. I measure again the trimmer and have (like it should be) a range from 0 to 49.1 Kohm.
thanks a lotJanuary 8, 2021 at 3:29 pm #16570
Take the LM13700 out of socket and see what voltage you get on pins 1 and 16January 9, 2021 at 9:32 am #16576
i get on 1 and 16 between 4.72 and 4.95 (moving the trimmer )January 9, 2021 at 2:03 pm #16580
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
Hopefully someone with a working circuit can post IC voltages to see if it’s a problemJanuary 9, 2021 at 3:51 pm #16584
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 knowJanuary 10, 2021 at 9:08 am #16594
if is not the IC, what should it be?January 10, 2021 at 12:03 pm #16599
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 readingJanuary 11, 2021 at 4:58 am #16613
there are 0 no small reading also if i change the scala of my tester and there aren’t connect to the ground.
i try to check all solder.
thanksJanuary 21, 2021 at 4:45 am #16733
i check all solder but all should be fine. any new idea?
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