nortel MICS 8x32 intermittent buzz on cpl handsets internal and external calls

[melbs1]

This one has me stumped. Let me know if you have seen this and/or have any suggestions.

MICS 8x32 plus 0x12 (fiber)- 5 phone lines and using 30 M7310 handsets.

Approx 6 handsets hear an intermittent buzz on internal (intercom) as well as outside line calls. There are 2 of these 6 extensions that have the issue much more frequent than the other 4. Several times per day.

For those 2 extensions, I have replaced the phones (now using Rel 22), changed pairs on the cable run, replaced cross connect, made sure the amphenol cables were secure to their ports, changed the power surge protector and the power outlet the phone system is connected to. After all of this, the problem is the same as before.

What's left? Thanks in advance for any help.

 

[curlycord]

My first thought is a ground issue.
Also maybe a failing power supply or mobo.


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[flafoneguy]

Could be a failing flourescent light ballast next to station cables. Or it could be a similar power feed (AC or heater) running parallel to the voice cables and imparting RFI. If you get clear sound direct from station port on short test cable run near the switch - then I'd have start looking at those AC power feeds laying in the ceiling or ballasts in proximity to the problematic exts.

Mike P.
flafoneguy

Is it close to beer:30 yet?

 

[melbs1]

Thanks for the suggestions. Have tried different power outlets and different ups. I made sure the cable run is not sitting on any power lines or lights.
Might try hooking up a phone direct to the station port on the 66 block but since the problem is intermittent I would not feel sure the cable run was the issue if I had a clean line for a few test calls.
I have not heard of an issue like this being caused by bad 0x16 or possibly the power supply in the 0x32 cabinet but looks like what I am down to checking at this point.

 

[silver987]

I had a similar problem, I found a handset when brought to close to a computer it had a bad buzz on it. I know from what you said you changed the phone. Did you change the handset as well? That cured my problem, I'm just throwing this out there. Take it for what it's worth. If there's a computer nearby it should be easy to see if that's the problem.

Wayne T

 

[cook1082]

I had this in Washington DC on Capitol Hill it was sets near this one side of the building with the window. CNN microwave signal was causing the problem.

 

[melbs1]

Thanks again for the input. PCs are not near the phones and there are no radio or microwave signals anywhere near this building that I am aware of. I have plugged into a panamax surge protector and it into a differnet 20amp outlet than it was before. The problem is gaining ground with 2 more phones reporting issues now. some extensions on the main cabinet extensions and some on the 0x16.

power supply on the main cab?
If i was to earth ground this unit how do I do so?

Thanks

 

[curlycord]

The ground comes from the outlet and pass through the third prong, check it with a basic tester.
Are you in the UK?

-Check the phones AT THE KSU! this will omit anything outside the phone room.
-Have you asked for the outlet to be tested by an electrician yet?
-Check for ground at the AC plug
-Check the voltage at the AC plug
-Replace the power cord from AC plug to KSU
-Replace the power supply on the KSU if need, 1 minute job.

You should probably nail this down in one visit.
Sounds like something changed in the building.
I think grounding issues are noticeable on ATA ports but digital ports I have yet to experience.

Also transformers in electrical rooms can sometimes cause issues.





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