[Asterisk-Users] Qs about FXO/FXS cards

[Jim Van Meggelen]

asterisk-users-bounces at lists.digium.com wrote:
> On Sat, 2005-01-01 at 16:14 -0700, Michael Welter wrote:
> 
>> Since you asked, and since I'm well into this bottle of Merlot on
>> New Year's day: 
>> 
>> 1.  Power alarms.  WTF does that mean?  Wish I had some support docs.
>> 
>> 2.  On bootup, "Excessive leakage module x, ProSLIC failed Auto
>> Configuration".  Again, WTF?  Reboot and it's ok.  But, just a reboot
>> after driving 100+ miles to the client site is not a good option.
>> 
>> 3.  On bootup, a LED won't light.  When zapata gets to it, it can't
>> find the channel.  Usually means a complete power cycle to get it to
>> work. 
> 
> Those first 3 all sound like you have a problem with power
> supply and consistency. You don't mention what modules you
> have in the cards, but I bet you have FXS ports and have too
> light of a power supply for the job.

Oddly, the maximum power requirements of the TDM400 (fully loaded with 4
FXS modules) is 20W. That'd have to be a pretty weak power supply (or
heavily loaded chassis) to have problems drawing that power. Still, I
agree that the power supply is a suspect. I'd want to know who makes the
power supply, which model it is, and whether that model has a good
reputation. An electrically noisy power supply could cause the kinds of
anomalies described. So could a faulty supply, of course.

More important to my mind is the overall quality of the power feeding
the system. Is a dedicated electrical circuit employed? Isolated,
insulated grounding conductor right back to a separately-derived source?
Power conditioner? So many of the problems people are having with the
TDM cards sound like power-quality issues, one has to wonder. I don't
mean that as a panacea, because the TDM400 troubles seem to go beyond
any one issue. It's merely one thing that might bear looking into.

It'd be nice to see some statistics on not only what percentage of
TDM400 users are having problems, but also what kind of environment
they're in. I'd want to know about the elctrical environment,
manufacturer and model of each system component (power supply and
motherboard especially). I'd also like to get a report from a circuit
analysis performed on the PSTN loop. I realize that much of this would
be impossible to get, but one of the most important steps towards
solving a bug is being able to identify the conditions which cause it.
So far that data is not known, which is a large part of the reason the
problem is not getting fixed - no one knows exactly what is causing the
troubles - we just have symptoms.

What if, for example, the TDM400 issues were a cumulative thing? If you
had over 6dB of attenuation on the PSTN loop, coupled with greater than
5V potential on the neutral-ground of your elecrical receptacle,
compounded by a cheap power supply, exascerbated by a Via-chipset, would
you not be virtually guaranteed some strange behaviour? But if your PSTN
was -3dB, your electrical feed derived from a power conditioner, your
power supply manufactured by PC Power & Cooling, and a ServerWorks
chipset-based MoBo, would your system always be faultless?

With enough data, we could really start to hone in on this animal.


>> 4.  A TDM card that isn't recognized at all.  DOA.
>> 
>> 5.  Impedience matching to eliminate hummmmmmmmmm?
>> 
>> I'm calling Matt on Monday, and hopefully he'll RMA these cards.
>> 
>> I hope that everyone that has a life is out enjoying the New Year.
> 
> 
http://lists.digium.com/mailman/listinfo/asterisk-users

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