sundance-communications.com/forum Forums General General Telephone & Systems Information Valcom Speaker

Not sure if anyone can help me, but here goes....I am currently troubleshooting a valcom speaker system that is used only for background music, no connections to the phone system. The problem is there is an intermittent buzzing noise that will come across the speakers for 5 to 10 seconds. I can disconnect tip and ring from the V2000 control unit, only have power going to the speakers, and the buzzing can still occur. I changed power supplies, but that did not help. I have disconnected all the speakers, added them a section at a time until all spaekers were hooked up, had no buzzing during this "test period" and no buzzing for ten days. Yesterday the problem returned. Went through the same disconnect and reconnect routine today, thought I had it isolated to one area. Disconnected that one area and the buzzing showed up just when I thought I had narrowed it down. Has anyone had any experience with a problem like this? Any ideas? It seems something outside of the speaker system is inducing noise.

Are you using one power supply for all speakers?
I would look at your power source and see if there isn't some piece of equipment on the same circuit coming on when the noise starts. I don't know what kind of business your working in, but if you could start turning off breakers when the noise starts, that might point to where the inductance is originating.
Mark

welder, electrical fence, light ballast. Check whats on the ac circuit going to power supply.

Start noticing what is on when the noise occurs.
eliminate one at time.

What source is providing the music ?

It is a doctor's office. Two power supplies. Music provided by a radio, but the radio can be shut off and the noise still occurs. I suspected a ballast in the fluorescent lights. I have turned many of the lights off and on in an attempt to recreate the noise but no luck so far. Like searching for a needle in a haystack! Also several refrigerators but they don't seem to be the source.

x-ray unit ? and the list goes on and on.
Do they have a fish aquarium ?

Heat tape under bldg.

Bad wiper on sw. bank. (lol)

How about bad bond on cable tv unit ?
How about the outlet you are using or sharing ?

Well since you said you have it in sections; when it returns again disconnect/reconnect one section at a time until it goes away.

Could there be mice or rats that have tasted/chewed the wiring somewhere causing a ground short when it's moved? Seems unlikely but I've see it happen, after weeks of trouble shooting.

Could the power supply be causing it, because of the circuit it's on? Have you tried running a good ground to the common ground of the PS?


Could it be the radio putting out the hum?

are all the olm settings on the speakers the same...

what kind of cable r u using...

What sort of buzz is it a low freq. like 60hz then you have a ground loop or short. A light dimmer may cause the sound to change, if theres ticking with the buzz then it maybe a ac motor. also listen for a click at start or stop of noise caused by contact closure like the old photo copiers. Another thing you can try is resistive load across the audio line to the speakers to see if noise stops

Buzzing noise for 5 to 10 seconds has to be the x-ray equipment.

This is most likely a ground on the tip or ring of the audio pair. The fact that it's intermittent is that whatever it is, whether a nicked cable, sloppy stripping of conductors on the speaker terminals, or an intermittent open in the tip or ring means that you have your hands full. An intermittent open will cause a huge hum. This happens when people are looping cables from speaker to speaker and twist the stripped ends together before placing them under the screw terminals. When the screw is tightened, one of the wires might be broken but is still close-enough in contact where it is usually good.

I'm with Ed on this. It has to be a speaker wiring problem. How many speakers are we talking about? Start replacing the wiring unless you can isolate it.

-Hal

After rereading your 1st post I have to say in order for it to be caused by the x-ray, the x-ray would have to be off for that ten day period.
If the x-ray was used during that time then I also have to agree with Ed.

is it in a office complex ?

could be something in another office causing it .

can you get acsess late at nite or on weekend ?

Since everyone else is guessing, my guess is 1 bad speaker ruining the whole bunch.

People often overlook the AC side of the equation. Others here have already mentioned the AC side. Noise induced on the AC side will travel to the DC side. Install a good ups to eliminate this possibility.

Could be a current problem/overheating power supply. Most Valcom powered speakers require about 250mA each. Check the size of the supply and the number of units on each supply.

We have a valcom system installed that is picking up ticking from alarm system wire. If i use my Progressive amp probe almost anywhere above ceiling tiles i hear it. Have to go back and replace wire with shielded,I should have looked first.-----------John

Something else that hasn't been mentioned is radio interference. Also, can you describe the noise? Is it a tone or a buzz, high or low pitch, constant or varying, always the same length?

Was one doctor away for a part of that 10days test period? I can think of several pieces of equipment that might be found in a doctor's office that would cause it, from an x-ray machine as noted above, an electric cauterizer, electroloys machine, add in paper shredder, photocopier, etc...

Thanks for the tips. This problem started about 4 weeks ago, the system has been in place about three years with no problems. The customer said nothing obvious had changed in the office (no construction, new equipment, etc) that could have started this problem, but since the problem source could be so many things who knows. The noise is not consistent, it can happen once in two hours, three times in ten minutes or not for days. When the noise occurs it pretty consistently last 5 to 10 seconds. A buzzing/staticy noise that typically increases in volume before just stopping altogether. This one is going to be a pain in the --- to figure out!

Are there any water leaks in the roof or tenant

above ?

Also Valcom has tech support in the factory.

How many speakers and do they all make the noise sounds like it may be a bad amp on one speaker if you can short the tip/ring then it should silent all outside interference then if one speaker is nosiey replace it or if a group of speakers is noisey you have wire problems

can it be cell phone interference? I have my cell phone next to my desktop speakers and the sound often goes BONKERS!

This could be powered from 24 volts DC or a Valcom AD to 24 volt adapter. That would eliminate the AC power supply. Two cheap car batteries or whatever and they recharge them at night.

You could use an isolation transformer on both the 2002 and the music source, that would eliminate AC power hum.

The power source puts out 12 "UNITS" of power, could you be exceeding this with the number of horns?

Are all of these speakers home runs?

I don't know how much experience you do or don't have, but with any of these posts, the more research you do, the more info you give us, the more situations get resolved.

A little more information might be good to point the way.

You do know that the last post was almost a month ago?
I assume that this issue was long since resolved.

Well the post before mine was a day earlier than mine. OPPS I got caught trying to help and didn't notice the post before the post before mine.

Now if there were some moderator around who would diligently determine the thread was finished, then said moderator would make a last post: This thread is closed, and lock its little keyboard input out.

I nominate Paul to be responsible for determining a thread to be closed and make it impossible for future comments. Its your job now, I just voted and no one else gets a vote, that is just the way it is.

Shut it down Paul, you are in charge and you have determined this thread is finished because I said so.

Thanks, and Happy New Year, L'Shanna Tova 5767