[Asterisk-Users] Hum/bux on line

Rich Adamson radamson at routers.com
Sat Apr 10 10:41:37 MST 2004


Mike,

> After Qwest pronounced my circuits as within spec. (yes, disconnected 
> from the house) I listened on the lines with my butt set.  Clear of all 
> noise and hum.  I then got my box of Cat3 and laid a circuit around the 
> outside of the house and into my lab.  Still clear of all noise and hum. 
>   I then connected the circuit to the Adtran and made a call.  Lots of 
> hum and buzzz.
> 
> As I said, I replaced all the Adtran components with no effect.  I then 
> switched the Adtan with one at a customers site (Saturday night.)  The 
> customer lines were clear of noise.  I brought the customer's Adtran 
> back to the house and still had the hum and buzz.

Now there are only three components left: 
1. Asterisk
2. power supply for the Adtran (assuming its separate)
3. the physical connection of the phone line to the Adtran.

I'd look very close at the phsical connection to the Adtran, absolutely
assuring yourself the tip/ring is attached to the proper pins, no 
solder splashes between pins, nothing is touching the chassis or
any form of ground, etc, etc. If you're using a special cable (I've
never seen an Adtran so don't have a clue how it connects to tip/ring),
then either substitute the cable or bypass it one way or another.
It almost sounds like either the tip or the ring side of the line is
touching something else (eg, chassis).

If the Adtran is using a stand alone power supply, substitute that.

Can't even imagine anything in the relm of asterisk causing this.

> The Qwest guy had this handheld test set that you talked about.  He said 
> the garage manager confiscated his VOM when he was given the test set. 
> Narrow thinking by management, wouldn't you agree? Oh well.

Using a VOM isn't going to find the problem. The noise level is far to
low for it to even register. The noise meter is the right tool assuming
it is a real noise meter.

Leaving for lunch, but call me at 700-434-5395 in a couple of hours.
I'd like to hear the noise.

Rich





More information about the asterisk-users mailing list