[Asterisk-Users] TDM400P Revision question.

[Rich Adamson]

> >>My specific issue has to do with ringing on my FXS ports.
> >>
> >>A Northen Telecom Harmony phone (circa 1983) rings normally but when I connect my newer GE 
> > 
> > 2.4GHz cordless I never get more than 1/2 ring (it lights up and works fine... just can't 
get a 
> > ring from it). Normally I'd assume that it's a low power issue on the FXS port but with a 
phone 
> > rated at 0.1 REM?
> > 
> >>I do have some strange voltages though....
> >>
> >>ON-Hook: ~48V DC, 107V AC (this really concerns me...)
> >>Off-hook: ~6V DC, ~12VAC (where the hell is this AC component coming from???)
> >>Ring: 0V DC, ~45V AC
> >>
> >>Suffice it to say that electrically this is completely out to lunch... I'd like to throw an 
> > 
> > oscilloscope on the line to see what's what but I'm having trouble finding one.
> > 
> > 
> > That on-hook AC is a real problem "if" the voltmeter is accuate.
> > 
> > Couple of things to try....
> > 
> > 1. Go to the demarc, disconnect the in-house wiring and measure the AC
> > component again (only looking towards the telco's CO).
> > 
> > 2. Disconnect asterisk and install an ordinary analog phone. Take
> > the phone off-hook and measure the AC. If the value is very small,
> > then the voltmeter is measuring induced AC on the "unterminated"
> > wiring. (The phone being off-hook creates the termination.)
> > 
> > Put the phone on-hook and measure again. If the value is large, then
> > go looking for the source of the induced AC. Things like wall-warts,
> > fluorescent light ballasts, any device with a transformer in it,
> > electric motors (of some fairly large size), desktop high intensity
> > lamps (with internal transformer), etc, can cause inducedAC "if" 
> > they are within inches of the wiring.
> > 
> > Using a scope would be good, but it will only validate the voltmeter
> > results; nothing more. If you're unsure about the quality of the
> > voltmeter, borrow another one from someone and compare the results.
> 
> Doesn't anyone use Google anymore?
> 
> http://lists.digium.com/pipermail/asterisk-users/2005-April/098934.html
> 
> Also:
> 
> http://www.google.com/search?hl=en&q=site%3Alists.digium.com+boostringer&btnG=Google+Search

Eric, those links have nothing to do with his stated problem. The
problem is "105v AC on the pstn line when on-hook and no ringing".