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Low Voltage Toner Questions

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Douglas Cyr:

I just started working on upgrading/servicing a churches sound system - the current state is quite a mess with a lot of unused/defunct I/O, unlabeled/messy racks and no as-builts or schematics at all.

I have plenty of testers like the Soundbullet, Soundtools XLR Sniffer/Sender, and Fluke Networks PRO3000 low voltage toner.

The question is: if I send the tone down a line that's connected to something on the other end (A&H stagebox, amp, passive speaker, etc) will this be bad for any of that equipment?

Douglas Cyr

Mike Caldwell:
Short of maybe the speaker lines (you maybe able to hear tone at the speaker) I would disconnect all cables at both ends and get a helper so there is someone at each end, it will go a lot faster.
You stay at the rack or sound booth while the helper runs around looking for the other end of the line your sending tone down!

Erik Jerde:
Without knowing what's on the other end it's a complete crapshoot to say if you can damage it.  Most testers aren't going to output anything more than the voltage that they're running off of.  I've never heard of one charging up caps for a higher voltage pulse but I can't say it doesn't exist.  Most pro gear isn't going to care.  The circuits/transformers used to balance the signal will be fine.  If it'll survive standard phantom power being plugged into it then your tester shouldn't bother it - most of them run 9V or less.  Some gear may "eat" the signal though.  I know back in my full time IT days (nearly 20 years ago now) I had a special adapter to use when toning out ethernet lines.  Switches would eat the signal so you could never find a line if it was plugged in.  Those were the 10/100M ethernet days though so my adapter just flipped the tone signal to one of the unused pairs and then you could tone it out just fine if plugged in.  Probably wouldn't work these days with gigE that uses all 4 pairs.

Consumer level gear or just cheap crap gear is a completely different situation though.  I've seen more than one computer with a blown headphone port because someone plugged it into a console directly and then turned on phantom.  Not sure what voltage it takes to blow one, I've never had the repair dollars to spend on a real legit study of the question.  Mike's advice is good, just unplug everything you can find and then test.  If you've got multiple ends terminating in one location have your assistant with the Tx unit and keep the Rx at the central location.  It's so much faster with a helper and it's a great way to break in an apprentice.

Brian Jojade:
What Erik said.

FWIW, I've never blown out any gear by connecting the transmitter.  I have had it make undesirable noise when connected to an active input, but no damage was done.

However, I HAVE had systems blow out the transmitter on me.  Once plugged into an older phone system that used some non-standard way of supplying power to the phones.  Transmitter dead.  Day ruined.  Now, this was a super el-cheapo transmitter, but that unexpected voltage killed it on the spot.

When tracing wires, it's generally good to TRY and make sure you're dealing with dry lines whenever possible.

Douglas Cyr:
Thanks for the help guys, I'll try to trace open lines but won't be too scared of running it to a passive speaker or mixer input.


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