PedalPCB sproing  [SOLVED]

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blaise
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Post by blaise »

Was anybody successful building a JJ Rocket Boing clone using pedalPCB sproing PCB? I reflowed all my solders, checked for bridges, switched my IC for different kind of opamps without success.
The output gain is way below unity. When plugging a guitar, I get no signal at all (or so low that I can't amplify enough to distinguish it from the static noise).
With an audio probe, I notice that the signal out of the first opamp (pins 1-2 or IC2.1) in the schematic at https://docs.pedalpcb.com/project/Sproing-PedalPCB.pdf is already way below unity. Would a resistor in the feedback loop between these two pins help (not that I know how I would handle this on the PCB...)?

Does anybody have any other idea? I'm kind of bummed. First pedal using a PCB after building 10 or so from vero or tagboard without too much trouble...

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grrrunge
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Post by grrrunge »

Sounds odd. Could you measure the voltages on all 8 pins of IC2 and list them here.
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cspar
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Post by cspar »

Have you double checked that your 3pdt is orientatied correctly?
"There is discussion, brainstorming, disagreement, testing, verified layout and schematic. We are the fucking stompbox university -- only for those who still read though..." - Modman

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blaise
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Post by blaise »

cspar wrote: 06 Dec 2023, 14:51 Have you double checked that your 3pdt is orientatied correctly?
Not the issue but thanks for steering me in the right direction. It was a bad switch. I am so used to testing circuits before boxing them and wiring jacks and switches that it did not come to my mind.
In retrospect, once I had checked all voltages, it should have been the next thing to check.
Lesson learned!

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blaise
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Post by blaise »

grrrunge wrote: 06 Dec 2023, 13:52 Sounds odd. Could you measure the voltages on all 8 pins of IC2 and list them here.
All voltages made sense (see below). It was the switch ...
Thanks!

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scotheath
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Post by scotheath »

Late to the party for sure, Just finihed this board, only my 2nd pedal PCB build. Always been Tayda or Madbean boards. Like you I've always rocked before boxing with my test rig. Tried that no sound, then wired in jacks and power, still nothing, Went through with DMM, Then audio prob, no sound past input, nothing at R 1 or past. All volts are good. After Reading your post, do you have to have switch wired in order for this to work??

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mauman
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Post by mauman »

scotheath wrote: 29 Oct 2024, 22:29 Late to the party for sure, Just finihed this board, only my 2nd pedal PCB build. Always been Tayda or Madbean boards. Like you I've always rocked before boxing with my test rig. Tried that no sound, then wired in jacks and power, still nothing, Went through with DMM, Then audio prob, no sound past input, nothing at R 1 or past. All volts are good. After Reading your post, do you have to have switch wired in order for this to work??
Verify you have a signal at the input side of C1, but not the output side. If so, then something past C1 is killing your signal. Then I would, in any order: (1) verify the value of R1, should be 1 meg. If it's too low it could be shunting your signal to Vref. (2) Verify IC2 is installed the right way round, and has +9V on pin 8 and ground on pin 4. (3) Check soldering on C1, R1 and IC2. (4) If you socketed the ICs, remove IC2 and see if there's a signal at the socket's pin 3, without power applied. (5) Without power applied, carefully eyeball and use your DMM on the traces between C1, R1 and IC2 pin 3, there could be a solder bridge or strand of wire from there to power or ground, or a trace could be open. (6) Replace C1. (7) Replace IC2.

Let us know.

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scotheath
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Post by scotheath »

By signal do you mean with audio probe or with dmm?

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Post by scotheath »

With audio probe no signal at C1, with DMM 9.14 and zero at C1.
R1 is a 1.01 meg
Ic2 is installed correctly 9.22v at pin 8, 0 volts at pin 4
I have re flowed all solder joints
I removed IC2 and checked at pin 3 w/ out power, no siganl with audio probe
clean between C1, R1 and pin 3

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scotheath
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Post by scotheath »

Turns out switch has to be wired in with PedalPCB boards to function correctly. I've got it working

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