[HAM] OT: looking for sound system diagnostic help

[LJRose]

Hi Hams

I didn't know where else to ask this kind of question.

Please contact me off list if this is too far afield at 
lloydjrose at verizon.net

Behringer--bad reputation for being failure prone--understood!

Yet, all the Behringer devices I've been using seem ok so far, except...

I use a SHARK in my church sound system setup.  The SHARK is a digital 
swiss-army knife audio gizmo.  Feedback filters, compressor, level 
matching, noise gate, etc.  I have two live mics going to a small Mackie 
board, and then to a mic input in the church's system (they're all over 
the place here and there).  I'm using the SHARK to chase feedback and to 
match levels, between the board's hi level out and the mic level input 
of the church's system.

The SHARK, after running awhile in the church, goes into a digital 
frenzy and locks up (crazy display lights, and a loud hissing sound).  
This symptom only occurs if I'm running signal through the device, and 
only at church.  I cannot replicate this failure at home.

I suspect there's something buggy with the church system, and I'm 
wondering if I put some kind of isolation transformer between SHARK and 
the church maybe they'd get along better.

If any of you want to take a stab at this, I'd be happy to hear from 
you.  Loud hissing in the middle of a church service is not good for my 
job security.

thanks

LJR