Help navigating with audio probe

[ac30irons]

So I have built this rangemaster (done loads of these) with a NPN transistor. It WAS working. The person who I did for says there is no sound on engaging the pedal (works in bypass and led is good.)

My thoughts are to get in there with an audio probe to work out what has gone wrong (after visual checks etc.) Here is the issue, I just can’t get my head around how to follow a schematic. I know I start at the ‘in’ of the jack and then the board but where the hell do I go then. Thank god it’s only a handful of components. There is no D3, IC, C6 or C8 in this build.

If anyone could help with a road map I would appreciate it.

 

[Feral Feline]

Also, there are many schematics online marked up with the audio path.
Go spelunking, find the "audio-path" schematics, compare them to other schematics showing the audio path.

Learning to read schematics, learning what components do what, and learning how to follow the audio path — is all a journey you have to take a step at a time. There's no magic portal to teleport you to instant higher-understanding, like any endeavour done well it takes practice.



I don't collect "audio-paths" anymore since I can basically figure it out now, at least most of the time, just looking at a schematic, but...
Here are a few audio-path examples I collected from GPCB, from when I first started building pedals:



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Notice how most schematics are drawn with a fairly simple left-to-right audio-path?
Note how delays differ, see how tremolos or autowahs have LFOs and envelope-detectors respectively acting upon the audio-path with out being part of the audio-path...

Like the last example above, the Zenith; note how the path goes L>R, but above the first op-amp in its feedback loop are clipping diodes — that's part of the audio-path in one sense, you'll hear signal with the audio probe there, but really those diodes are acting upon the signal-path more-so than they are a part of it.

What about that Mini-me chorus? Two audio paths in parallel to each other. Look at the dry signal's audio-path marked in yellow and follow it through; now see if you can trace the wet signal through to where it rejoins its dry-counterpart...




Seek out some more audio-path marked schematics online, but nothing beats learning by doing and working one out yourself, just as Harry Klippton and others have indicated.