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Posted By: jnimmick 25Volt sound/paging system in supermarket - 06/10/14 11:30 PM
have a supermarket customer with what I find as a strange issue. They have a 25volt system with numerous speakers connected. Over the last few months various sections of the store (bakery, deli, gen merch) have seen a decrease in the volume coming out (keep in mind no one has touched the system or speakers). I am at a loss as to where to begin troubleshooting or what could be causing this issue. Have at least 8 speakers this has happened to. Any ideas/help would be appreciated!
You sure it's a 25volt system? That voltage is normally used for Education sites.

First, is this a multi-zone system? and is the failures happening over different zones?

Is there multiple amps involved?

Are Volume controls in use and if they are. Are they inline with the speakers or do they connect to the controller (assuming a zone system).


K-Mart used to use 25 volts on their amps. A sure sign that someone messed with the speaker grid is the amp would start to cook. A good impedance meter will tell you if you have bad speakers, but you should also look for a line sitting on the ceiling grid or the mounting bracket. Grounding one side of the line makes the system work really hard.

Carl
Any work done by sparkies lately???

If like most markets just one long loop.

Could be short, bad speaker etc.

First put in a new speaker where the low volume is.

If they have a lift just start breaking the line every 5 or 6 speakers, won't take long.

If you have an Impedance Bridge use it first.

I work with some Mexican Markets here and the locals have a habit of tapping in with unauthorized speakers where they want music.
Posted By: Rcaman Re: 25Volt sound/paging system in supermarket - 06/12/14 05:39 PM
If you are doing paging system work, I highly recommend Mike Sandman's TOH3S meter. It will save you many wasted hours trying to hunt "snipes." This meter will allow you to determine if the amp is capable of supporting the load. If you break the speaker line in half, this meter can show you if there is a high load situation.

I installed and serviced sound systems for 40 years without this meter. Now, I can't imagine working on a sound system with it.

Rcaman
What happened to the OP?

A follow up would be nice
Carl's post reminds me of a grocery store I worked at. Paging and music were there just very low. Nothing documented as far as how the legs were laid out. There were multiple legs. Isolated to the one bad leg. Then had to start following that leg. Eventually I lifted a ceiling tile by one of the speakers I wanted to use for a test area and a wire nut fell out AND the music came back upstream from my break and in the rest of the store. Turns out this was a "new" section and they spliced it in using wire nuts. One of the nuts fell off and, in addition to this, the store would hang banners so somehow the wire nut got knocked off and the bare wire side jammed into the ceiling grid by the tile.

Secured the cable up into the ceiling so it could not be disturbed and problem solved!

If you don't have the tools noted above remove all the legs from the output of the amp. Grab a speaker and connect to the amp output and make sure the amp is not the problem. Keep your speaker connected while doing the next step. After this, start putting the legs back one at a time. When the volume dies then you have a problem on that leg. If there is only 1 leg then you will need to start working downstream from the amp or down the leg you have determined has a problem. You can now put the speaker back or take it with you as you work in case you come across a speaker you suspect may be bad. Keep in mind that as speakers were added they might have broken off into different legs as they added on. Go to the first speaker and pull the wire going to the other speakers. You should notice the first speaker work right (assuming the speaker is good and there is not a cabling fault between the amp and the first speaker). You can either go to the next speaker and rinse/repeat or work several speakers down if you are sure of the speaker wiring layout. Assuming 1 wire daisy chains all the speakers and discovering they started another leg somewhere will drive you nuts so I would advise following the wiring. Time consuming but eventually you will find the problem and have a good understanding of this system for future calls.

If this is a regular customer of yours, spending some time documenting how the paging is laid out can save you considerable time and stress when it comes to service calls.
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