atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services Security, Alarms and Paging Paging issue

Here we go in a nutshell. I have a store where the phone system, panasonic 1232d, is located in the back of the store. The amp, TOA 1120, and music source are located at the front, approx 150 feet give or take. This location has been set up this way for several years. All of the sudden the music stopped working unless you pull the paging off of the amp, paging worked no matter what. If the amp is moved back at the phone system everything works perfectly. My electrician ran new cat 5 to the front, same result. I will say that the cat 5 was not shielded, but I can't figure what caused this issue all of the sudden. I don't want to have to run more cat 5. Any ideas

Ground loop
Some how you are getting a ground loop that is killing the radio audio. It could be from a wire shorting to the building ground or poor electrical wiring. If it works perfect with the amp at the phone system why not leave it like that?

Or look up 'humbuckers', 'isolation transformers', etc, on the internet. Most sound equipment manufacturer's make something along that line, and many major sound equipment wholesaler's have something of their own. John C.

Inputs to an amp should ALWAYS be shielded. If you're feeding a 600 ohm output from the KSU to the telephone input on the TOA you might not need shielding.

Which input is the music going into? Are you using shielded cables for that? What's your music source? Is it colocated with the amp?

Are you shorting out the Background music when you page (you should be!) Maybe there's a problem with the shorting circuit.

But go with what Merritt said. If it works in the back. Leave it there.

Or start troubleshooting.

Give us a full description on what is hooked up where and what is going on. We'll see what we can do.

Sam

All of the sudden the music stopped working unless you pull the paging off of the amp, paging worked no matter what.

I'll assume that the page input has priority and "ducks" the music when a page is made. I'll also assume that this is accomplished using the VOX function of the amp- you are not using a contact closure in addition to the audio from the Panasonic, correct?

Since you can eliminate the 150 feet of cable by moving the amp to the system location and the problem goes away, you have to be picking something up on that cable that is triggering the amp ducker just like the page audio would.

It's very strange that the most likely cause would be hum but you don't hear it from the speakers. Correct? What's also strange is that this began after several years of operating properly.

Does that TOA have a sensitivity or threshold adjustment for the ducker? What happens if you turn the page input control all the way down. Does the music return?

I'm leaning towards a problem with the amp unless we can see otherwise.

-Hal

Hi all. Thanks for the feedback. I have tried using in isolation transformer, to no avail. The music source is a computer, but I tried a separate source to rule that out. The voltage is right, however I can't say that the ground in the store is "perfect." I have turned the "sense" up on the amp, tried a new amp. All I can think is that it is a ground loop issue. Right now the amp is ok where it is, I just wanted to move it to a safer and more convenient location.

Are you saying you are trying to move the amp away from the 'unsafe' area where the phone system is? If that's true, then the phone system would be the priority in my book! Music is nice, but communication is BETTER! John C.

If it were a ground loop issue you would have a hum problem and you would hear it. You still haven't answered my question, do you hear any hum when the music is not working??

-Hal

Sorry, been out of town, working of course! There is not a hum in the system, that I can hear anyway. It is an open ceiling grocery store, so maybe I can't hear the hum, but I do have a good ear. Can wireless devises such as Arlen or wireless scales (grocery store remember) interfere at all?

Just for giggles, this phone system is located in the motor room, refrigeration compressor room, so I agree that all of the comm stuff should be moved elsewhere, but that is above my pay scale!

While on the issue, I have a 130000 sf store with approx 90 speakers going in. We use TOA amps, but the TOA 724 amp doesn't seem to work for us. We experimented and were not please. We had to get a MOH module which really didn't work out well. Is the Bogen equivelent better, or are there any ideas you guys could provide? Thanks. Hey only been doing this 2 years! You guys are the experts!