[Asterisk-Users] tdm400p static - out of ideas

[Jorge Mendoza]

We have not experience with Digium cards. However we had similar 
problems when installing legacy pbx. The problem: local ground. One easy 
way to test the local ground is with a voltmeter measure the voltage 
between the CO tip wire (in open loop state) and local ground. This must 
be less than 2 VDC and must be stable (not oscillations). Correcting the 
local ground all problems were fixed.
When you plug a regular phone, the phone is floating and have not 
electrical contact with other devices, then there are not ground currents.
My guess is that there are some hardware design that are more sensitive 
than others to ground currents.

Hope this helps.

Jorge

Ryan Courtnage wrote:
> On July 8, 2004 03:22 am, Nicholas Bachmann wrote:
> 
>>Ryan Courtnage wrote:
>>
>>>Hello,
>>>
>>>Over the past several weeks, we have been having an intermittant problem
>>>with our deployment of a TDM400P card (4 fxo).  We have tried many
>>>things, and the problem still re-occurs.
>>>
>>>The Problem:
>>>
>>>Occasionally (every 48 hours), the TDM400p card will stop answering
>>>incoming calls on ALL fxo ports.  Attempts to send outbound calls on any
>>>Zap channel will result in hearing a loud 'static' noise on the line.
>>
>>Let's look at some possibilities of line problems:
>>What time does it stop answering? Is it ever during ALIT times (usually
>>very early morning)?
> 
> 
> It's totally random - morning/evening/afternoon.  Once it stops answering, 
> that's it, a reboot or module-reload is needed.  If ALIT for some reason 
> prevents the card from answering, it should be able to recover and begin 
> answering after the ALIT is complete.
> 
> 
>>Have you tried calling the telco to see if it could be their problem?
> 
> 
> When the card goes into the non-functional state, I can plug a regular phone 
> into any of the lines and make calls just fine.  After verifying working 
> lines and plugging them back into the tdm400p card, I still can't dial out 
> (the Zap channel will answer, but I will hear only static, and the call to 
> the pstn is never placed).  As well, incoming calls will not be answered (* 
> console will not even show the 'started simple switch on zap/x' message).
> 
> 
>>How far away from the CO/mux are you?
> 
> 
> Not too sure - it's in downtown Calgary - so probably not far.
> 
> There is the possibility that _something_ with the phone line is triggering 
> the problem.  Maybe it's some noise, an unexpected signal, some crosstalk ...  
> things that will cause unexpected behavior ... but also things that shouldn't 
> put the entire card into a non-functioning state.
> 
> 
>>Have you tried a new/different card?  If you didn't want to fork out the
>>cash for a new one, you could try a X100P/knockoff* on one of the lines
>>to see if that fixes the problem... if so you can deduce a bad card.
> 
> 
> I may have to push for a replacement tdm400p card from Digium.
> 
> 
>>Nick
>>
>>*I usually don't recommend the knockoffs, but for a day of testing $10
>>sure beats $100... everybody else should support Digium! :-)
> 
> 
> An acquaintance who is having the same problem has reluctantly replaced his 
> card with an openline4.  I would like nothing more than to stick with Digium 
> hardware - this thread and obtaining a replacement card is my last kick at 
> the cat.
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