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?
"Just because the forgoing circuits have produced results there is no reason experimenting won't lead to added results." L. E. Darling, in his article containing the earliest published vacuum tube synthesizer circuit, Popular Science Jan 1920

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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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