V70 Beltpack Just Producing Hum

[Sheriton]

I had an odd issue last weekend with one of my V70 belt-pack systems. I was running three of them plus my new V75 hand-held which I'd just used to update the firmware in all the V70 systems. All in RF1 mode.

This particular system had the L6 lav mic attached (I normally use headsets but this particular performer insisted on a tieclip). The system was used on someone else earlier in the show and performed perfectly, but once fitted to this performer, the problem hit. I PFL'ed him just before he went out on stage and all I heard was a loud mains-type hum with some harmonics and a slightly digital quality to it. No wanted audio at all; just this unvarying buzzing. I think the level was lighting up just the bottom segment of the receiver meter. It was far too late at this point to swap anything out but as he projected well, he made it through his act without the mic.

As it was a somewhat hectic show followed by a rapid get-out, I didn't have the time to go through any useful troubleshooting to narrow down what the problem might have been; unhelpful I know.  I set up the equipment again back at base and couldn't make it misbehave in any way no matter what I did. My best guess was a dodgy connection between mic & belt-pack but no amount of cable flexing and connector wiggling and loosening would produce any issues. The venue was at the bottom of a cliff on the seafront where even mobile phone signals barely made an appearance; with no venue WiFi either, it was the quietest RF environment I've ever worked in. The other systems all worked perfectly throughout; this one was also fine up until that one act.

My question therefore (and I know it's a bit of a stab in the dark) has anyone experienced anything like this or can anyone suggest a possible cause?

[dboomer]

My best guess is that the mic plug wasn't seated in the jack.  If it never happens again then you'll never know.  Other than that you should just do conventional troubleshooting substituting known working gear in place of the questionable gear until you can isolate a problem.

[Sheriton]

That was my thought too although my assistant who fitted it assured me that it was secure. I've since tried to recreate the issue by loosely connecting the plug but as all the pins make / break simultaneously (unlike a minijack connector for instance) it was either perfect signal or silence - nothing in between.

 

I'm chalking it up to experience but still hoping that someone else may have experienced similar who can shed more light.