Ground hum on Vonage

[1a22ip]

I have installed a Vonage RTP3000 Linksys and my non Vonage lines now have a ground hum. If I remove the RJ11 from the Linksys the non Vonage line clears no hum. Has anyone had this problem. I am getting no joy from Vonage.

Thanks
ED

1a2 to ip I seen it all

 

[ISDNman]

The so called "R" interface on Terminal Adaptors are unregulated and as such the quality varies widely.

Firs try plugging a phone directly into it. If this has the same problem, then the LInsys is simply defective and should be replaced.

First try another Linksys, there may simply be a problem with this unit. If another LInksys of the same model has the problem when connected to your wiring, it is most likely that the POTS jack on the Linsys does not use a transformer to keep the cost down. My guess is that you have LOTS of phone wiring. To keep noise (hum) down in this situation requires three things

a) Good balance in the analog "line" (e.g. in the Linksys TA) usually by using a transformer design

b) Good balance in the installation. This means that each connection in the system must be equivalent on each side of the line. If there is corrosion on the connection of one side, but not the other, this creates an imbalance and that cause noise pickup.

c) Twisted pair cabling.

If replacing the Linksys with something else cannot be done (at least as a test) then here are some things to check that MAY help

1) Check the connections on all the telephone wiring (eg at all junciton blocsk and at each jack. If there is corrosion or anything does not look perfect re-do the connection.

2) Disconnect wiring going to unusused locations.

3) If you have any phone (such as older trimline and princess phones) that send power over the second pair (yellow + black or white/orange and orange/white) disconnect this (these) power supply.

4) If your facility is wired with the old obsolete Red/Green/yellow/black "quad" inside wire, you should replace it. You may not need to replace it all - start with the longest runs first.

You want to use 4 pair solid twisted pair (you may only need 1 or 2 pairs now, but it makes no sense to install 2 pair cable). This will have 2 pairs of wires, each pair twisted. The pairs are:

Pair one
White with Blue stripe (Tip)
Blue with White strip (Ring)

Pair two
White with Orange stripe (Tip)
Orange with White strip (Ring)

Pair three
White with Green stripe (Tip)
Green with White strip (Ring)

Pair four
White with Brown stripe (Tip)
Brown with White strip (Ring)

Use a minimum of Cat. 3 cable (solid twisted pair), though it makes to just go ahead and install Cat. 5e

Good luck

 

[1a22ip]

ISDNman Thanks for the reply. I am not having a hum on the Vonage line. The non vonage line is getting the Hum when connected. By just removing the RJ11 from the TA the hum goes away on the non Vonage line. So you are suspecting a faulty Linksys TA?


Thanks
ED

1a2 to ip I seen it all

 

[ISDNman]

Hey 1A22IP (I like your handle BTW)

I see, I misunderstood originally.

Does disconnecitng the LInsys wall wart also make the hum go away?

Does the Linksys have a ground or does it float.

One of my theories is still the same as previous, that the Linksys is poorly balanced and the noise is being couple into the POTS line, though this theory does not fully explain things.

I assume the two share the same inside wire? If so is it quad or twisted pair?

Here's another question. I assuem that both "lines" go into some shared equipment (PBX, Key system, multiline phone, etc).

If so, does disconecting all equipment that share both lines (e.g replacing all multi line stuff with single line stuff for the testing) cause the problem to go away.

If so try reversing Tip and Ring on one of them and reconect the multi line equipment.

You might also doubel check that the pair the Linksys is on has no leakage to ground (e.g with nothing cvonnect check each side of the pair to ground with an ohm meter or put a tone generator that has an LED on it in talk mode and see if the LED lights). My thought here is that if this is an old installation with quad the yellow lead might have been connected to ground and the may be still some connection.

Best of luck)

 

[1a22ip]

If I remove the Linksys (RJ11) from the inside wire all hum stops. If I disconnect the liksys (RJ45) from the network Hum remains. I am sharing the POTS and VONAGE on 4pr cat5 inside wire. BL/W T&R1 OR/W T&R2 to 2 line phones. My next step is to isolate the Tip and Rings to seperate cat5 runs. I will also connect the 2 line phones to Line1 and line2 on the phones trying not to use the L1&L2 port. If This works there will be a problem getting to the phones on the 2nd floor.

Thanks for the help.
ED

1a2 to ip I seen it all

 

[1a22ip]

ISDNMan I have an update. I tried to separate the T&R for each line and still no joy. I then suspected a crap telephone. I unplugged the crap set and hum is gone. I am now shopping for a new phone. Thankfully it's only one set.

Thanks again
ED

1a2 to ip I seen it all

 

[ISDNman]

Given what you had said in your previous post, that was where my thinking was headed - something that had both lines going into it.

I am currently working with a customer that has lines from SBC , some on copper and others through an IAD, plus CLEC lines plus lines FXS ports off a Cisco router that all converge on common equipment made by me.

They are getting some *very* interesting problems when these lines are conferenced!

Glad you got it resolved.

cheers