Debugging fuzz face clone, now have buzzing amp

[mikepevans]

I built a fuzz face clone recently and hooked it to my amp.  I got some loud pops but nothing else.  I re-checked all of the connections and think that something wasn't properly grounded.  However, now my Vox Ac4tv amp exhibits loud buzzing when I'm not grounding it by touching metal on the guitar.  Which sounds like the amp grounding is somehow broken . Is it possible that something with the pedal did this? 

Is there any set of tests I can run (with a multimeter, perhaps) on a stompbox, that would tell me if it will harm my amp BEFORE hooking it to my amp?

I now am reading about how sending DC to outputs is bad, what exactly will this do?

Thanks,
-Mike

[Toney]

Hi Mike.
Well bad news is yes, you can mess your gear up by sending DC to the wrong places. Particularly the in/outputs.
Have you modded or changed the pedal since this happened? If not fire it up and measure. You can easily measure DC on the leads by putting a multimeter across the jacks. I do this habitually when testing a pedal. learned the hard way - send a dose of 9v up the input to my favorite guitar. Easy to do too. I slightly misaligned the header plug on my Crybaby and voila 9v right up the input. Fried my pickup.
So yeah testing for DC is a must.
You need to figure out exactly what is causing the buzz. First things first - Amp, guitar or lead. You need to swap them out with known good ones to begin.
You could get lucky. A crappy lead could be the issue. We have all been there...

[mikepevans]

Hi Toney -

Thanks for the reply!  Sorry if I'm ignorant, am I correct in assuming that the "lead" is the guitar cable? 

Is there anything else that I should be checking for?  I really hate to discover all the ways to damage equipment one at a time?   

Thanks!

[Toney]

Yep. 

[mikepevans]

One more question (hopefully) .  On the input jack there is the ring, which is connected to the positive lead of the 9v, the sleeve, which is the ground and the tip which is the input.  If I measure DC voltage connecting the negative lead to sleeve and positive lead to tip, I get no voltage, but if I connect the positive lead to the ring and negative to sleeve, I get nearly 9v.

Is that a problem?  I'm mostly dense on this stuff, but I find it interesting so I'm trying to learn.

Thanks!
-Mike