Residential line noise

[WildwoodEntInc]

I wasn't sure where to post this one...
I have a customer with a business in a residential setting, nothing fancy, standard phones straight off local telco.
He took a lightning strike and is now complaining of humming on the line, I tested from the customer access box and it's clean to the street. I unplugged all devices and still there is a hum, as I attach each jack back up the humm gets louder. I replaced the main wiring from access box to the punchdown block in the basement, with my buttset on, any line to any jack I reconnect generates a humm...
I checked the ground from the customer access entrance to the ground rod.. it's fine.

Any Ideas

 

[franklin97355]

Check for grounds between the wires to the jacks and ground. Sounds like a ground hum to me. Check each wire seperately.

 

[Cballinger]

Even a nearby lightening strike can short wiring. Your customer should probably contact their local utility company and have the transformer checked. Easy way to see if it is induced hum from the power lines, or being feed in via the power lines would be to tune an AM/FM radio to a dead spot and see if you can hear 60 cycle hum. If you do then hum is either being created or being feed down the power lines and could be feed in to their phone system via inductive coupling. If their phone system has a small wall-wart (power cube) this could have been affected by the strike as well, try changing that out or replacing.

 

[AvayaNovice]

Do you have a sidekick or a subscriber loop tester of any sort?

See if you have any ground loops in there, or any shorts.

Where was this lightning strike? Are we talking about down the street, or directly on his building? If so, was the telco's mpoe destroyed, or did it burn any of the carbons on the protector?

If you can get a hold of a subscriber loop tester, do some transmission noise tests and see what you find. If you're testing fine from the telco MPOE, try removing one of the existing jacks, bring it down to the MPOE and punch it directly onto the MPOE. See if you still get that noise with just that one jack and your own temporary jumper. Basically, elminate the possibilty of it being the IW. If it is the jack, then you know what the problem is... and you can replace them. If not, maybe it's the inside wiring.

 

[buitenhek]

Firstly, go through the house and have the customer turn-off and unplug all sources of internal EMI (microwave, bid screen TV, Sat-dish, computer, CRT, etc) and check for hum. If no hum, reconnect in order and observe which piece of hardware took the electrical spike.

Lightning strikes are tough buggers to diagnose. It would be simpler if all telephone cabling would be run like data cable (home run) versus the typical daisy-chain.

My guess is the electrical cable may have found a false-ground to a nearby staple or nail and may be arcing.
1. If the customer allows, turn off all electrical power to the house via the fuse box and pick a phone jack location, use your butt set to see if the hum persists. If not ---it’s the electrical cable inducing EMI.
2. If the hum persists, the inside phone cable is likely picking up the EMI. Try different phone drop locations to see if the hum gets louder or softer depending on which daisy-chain it is attached to. If you find a very noisy chain, disconnect at the 66 and see if that helps the others.
3. If it still persists, spool out 152’ or so of phone cable from front-to-back of the house and connected to the 66. If any hum is observed after connection, replace the 66.

I’m getting too wordy again (per requests) so I’ll stop here (for now).

Regards,
Peter Buitenhek
peter@profitdeveloper.com

 

[bobsou]

at the customer 's demark ,which come from the street does it have a carbon protector , check the carbons, unscrew then do you still have a hum ?

 

[ANFPS26]

Most protectors in the USA don't have the screw in carbons anymore. They are modular units and part of the interface. I would completely disconnect the wires to this module and wire the station wire directly to the drop and see if the hum goes away. If it does, the module is bad.

Jim

 

[WildwoodEntInc]

Found it guys... Thanks

 

[ANFPS26]

What was it? Please share.

Jim

 

[RandyVSP]

Experience has taught me the phone company will always assume its customer equipment. Best approach is disconnect completely all you r equipment ( bridge clips ) and see what ahppens. Then you can be on hold for 30 minutes and tell them THEY have a problem.

After a few service calls, the local Telco tech calls me, cause he knows Ive already checked the lines....He then gets it fixed faster....

I used to be able to call the guy at the local switch and he could fix it most of the time while I was there....LONG GONE are those days!

Isolate your gear first! Lightning loves my fax machines!

Randy