How to troubleshoot

[GeorgeFormanGrill]

Hey all:

Looking for some tips on how you typically go about troubleshooting pedals. I'm testing out a board I built out on a test box and something is way off. Originally, I wasn't getting any signal at all, so I triple checked I'm following the layout and found some spots with some sloppy solder work that was connecting rows incorrectly. Now I'm getting a signal, but it's crackly as all hell and the dynamics are all over the place. One second it's quiet and the next it's piercingly loud. Any advice on how to get this resolved apart from me throwing my tools in the ocean?

Thanks,
George

[jimilee]

With strip board. Run a knife down all the tracks. Check voltage with a DMM then audio probe. You should be able to track the audio pretty easily, just follow the components.


Sent from my iPhone using Tapatalk

[GeorgeFormanGrill]

Got it, thanks. What am I looking for when I'm checking for voltage? Is there a primer somewhere on how to check for voltage?

[GeorgeFormanGrill]

I checked out a few videos on how to get voltage readings, so think I get the rough gist of it. I've got a very cheap DMM. What setting should I be on to read the 9V battery?

[jimilee]

If I'm looking at it right, the top left 20 should be fine.


Sent from my iPhone using Tapatalk

[GeorgeFormanGrill]

Cool, cool. Thanks.

I'm not getting any voltage reading on the input, so I guess that's a good place to start!

What's the cause of getting an incorrect reading. Bad soldering job?

[matmosphere]

The guy who has the diygp shop (linked above) has a really good video about making and using an audio probe. Dead simple, no solder needed.

The basic idea is that you use a probe to directly play some recorded sound through different parts of the audio path of the circuit. By connecting the audio out to the leg of a resistor or capacitor or whatever is would normally have the guitar signal going through you can isolate where the problem happens. It's usually easiest to start at the out put of the circuit and work your way backwards to the input.

[GeorgeFormanGrill]

Oh, nice. Thanks.

I don't see the link to that video -- could you share?

[matmosphere]

https://m.youtube.com/watch?v=jWvIfDSxbIk

[jimilee]

That's for an audio probe, which is super helpful too. For voltages, the red probe goes to different point o. The board, the black goes to ground. I usually use the power supply ground.


Sent from my iPhone using Tapatalk

[Zerro]

Don't forget at first to controll the consistency of all tracks at PCB. Crackles in tracks or around soldered points. At your DMM use conductivity function. That diode/beep at cca 5. hour.

[GeorgeFormanGrill]

Nice. Thanks for the video -- super helpful.

And thanks for the tip on going to ground on the power supply -- I was able to finally get a reading when I figured that out.

@Zerro what do you mean about "controlling the consistency"? I've was able to find a few solder bridges using the conductivity function, but not sure how to check for consistency.

Also: I finally have a signal! But there's no sustain on the signal, especially if I crank up the fuzz pot. Here's a recording. Any one experience with this? What causes this kind of dead tone?

https://drive.google.com/file/d/1yNvYY2IX5-uaZAH7gWclpZFkBY4uqjOR/view?usp=sharing

[Zerro]

Hi, I meant if that tracks and soldered points are not interrupted, and/or damaged by etching or soldering. Sorry for my english, it's not my native language.

[GeorgeFormanGrill]

Ah, got it. Makes sense. Thanks for clarifying!

[GeorgeFormanGrill]

Anyone got any tips on dealing with a signal that's crackly/decays too fast?

Here's the sample audio again: https://drive.google.com/file/d/1yNvYY2IX5-uaZAH7gWclpZFkBY4uqjOR/view?usp=sharing