Tracing/troubleshooting a circuit with a MM

[Plaidesaurus]

Hey there, new to the forum. The Test Kitchen has some great tutorials which I've gotten a lot of good info from. But I was also hoping to find a tutorial on how to trace/troubleshoot a circuit from input to output with a MM. I may be overlooking just such a post but can someone direct me to that if it's on the forum? Thx

 

[EGRENIER]

Hey there, new to the forum. The Test Kitchen has some great tutorials which I've gotten a lot of good info from. But I was also hoping to find a tutorial on how to trace/troubleshoot a circuit from input to output with a MM. I may be overlooking just such a post but can someone direct me to that if it's on the forum? Thx

If you say input/output sound more like you want to trace audio and not voltage. Using a DMM isn’t the right tool, you want an audio probe.
check this for DIY:

Misc > Audio Probe : DIY Fever – Building my own guitars, amps and pedals

[DIY Fever] Audio Probe - very simple contraption that helps with debugging audio circuits

diy-fever.com

 

[jeffwhitfield]

Egrenier has a good suggestion. An audio probe is indeed an indespensible tool. Now, if you don't wanna hassle with building one, there are some pre-built ones out there. Bought one of these:

Rattlesnake Audio Probe | Rattlesnake Cable Company

Are you having a hard time finding out what component is failing or broken in your pedal project? This is where an audio test probe can be extremely...

www.rattlesnakecables.com

It's a little pricey but rock solid. Better than any of the ones I've built myself.

That said an MM is still handy. Can be used for other stuff that an audio probe is bad for. Two primary things you'll use it for is continuity checks and voltage readings. On occasion, you might find that the problem is due to a bad connection between two points on a board. Might be due to a bad trace on the board, a cold solder joint, or some other issue. Plus, you might need to do some voltage tests on things like IC's and transistors for further debugging. You'll have to do this anyways if you're biasing transistors for fuzz pedals and the like.

 

[Plaidesaurus]

If you say input/output sound more like you want to trace audio and not voltage. Using a DMM isn’t the right tool, you want an audio probe.
check this for DIY:

Misc > Audio Probe : DIY Fever – Building my own guitars, amps and pedals

[DIY Fever] Audio Probe - very simple contraption that helps with debugging audio circuits

diy-fever.com

Ok, thanks to both of you. I've had about a dozen successful builds but a couple of duds. I'll put these suggestions to use and see if I can sort them out.

 

[EGRENIER]

Ok, thanks to both of you. I've had about a dozen successful builds but a couple of duds. I'll put these suggestions to use and see if I can sort them out.

One more trick, if you have a looper pedal, record a loop and let it play, much easier than trying to strum while holding the probe

 

[Plaidesaurus]

One more trick, if you have a looper pedal, record a loop and let it play, much easier than trying to strum while holding the probe

Ha, great idea. On it.