Audio Signal Trace question

[djmiyta]

I think I've got a vague idea for an answer to my question but hoping someone else could confirm or deny my thoughts
So I built a Bad Monkey and I get a fairly loud hum when circuit is engaged so I try hunting down the source with audio tracing accidentally touched the output jack ground lug with the probe and heard loud and clear the signal I use for the tracing. So to me I've got something bridged or a component tied to ground that's not supposed to be . Thinking this is the cause of the hum
Can plugging in a board to power without a pf cap you forgot to install cause a component to fry or go crazy possibly cause my annoying hum?
or
Can someone provide tactics to hunt down this annoying hum? Also
Once you find where the issue lies on the board (possibly) what is the next logical step to take? Start pulling parts off the board to test? I've luckily had to troubleshoot very little out of over 200 builds so those skills are pretty weak and could use a little troubleshooting guidance.
Thanks to anyone and / or everyone for taking time to read this post and help they could provide

 

[Feral Feline]

Pics would help.

Might be as simple as reflowing a solder-joint on a jack or similar easy fix.

You said it was the output jack that you touched, so probably that jack. I doubt it's because something shorted to ground that shouldn't be because you got clean signal when you grounded the output jack with your probe...

Your output jack may not be grounded properly. What kind of jacks are you using? Is there paint around the hole of the output (or input)?
If so, scrape away the paint so the jack can connect to the enclosure.

 

[djmiyta]

Thanks for the quick response. I had reflowed the board once before but decided to do it again and although there is still a hum it was greatly reduced . Thanks again for the suggestions