[Asterisk-Users] TDM400P Revision question.

[Eric Wieling]

Rich Adamson wrote:

>>>>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".

The first line of this message says "My specific issue has to do with 
ringing on my FXS ports."


-- 
Always do right. This will gratify some people and astonish the rest.
Mark Twain