[Asterisk-Users] Major problems with TDM400 and specifictelephones: suggestions?

[Soner Tari]

I did the modification that Rich explains in his email on March 23rd below. 
I believe it works for me, because before this mod I was getting "Ouch, part 
reset..." errors at least once a week, rendering * unsuitable for production 
systems. After this mod, the system is running flawlessly for almost a month 
now.

The closest capacitor value I was able to find was 100nF though, but it 
seems ok. And I had empty module slots, so I did not have to solder 
anything, I just inserted the pins firmly to the slot (capacitors usually 
have long legs). Very simple.

Now I am quite happy with TDM400, and I recommend Rich's mod to everyone 
having such problems.

Thanks Rich...

----- Original Message ----- 
From: "Rich Adamson" <radamson at routers.com>
To: "Asterisk Users Mailing List - Non-Commercial Discussion" 
<asterisk-users at lists.digium.com>; <jnovack at stromberg-carlson.org>
Sent: Wednesday, March 23, 2005 1:32 AM
Subject: Re: [Asterisk-Users] Major problems with TDM400 and 
specifictelephones: suggestions?


>
>> >I've improved the stability of my card by adding a capacitor on the
>> >reset line. Hasn't taken a hit in over two weeks.
>> >
>> >
>> Is this the E/F or revised H card? Where and what cap did you install?
>
> My card reports as E/F; only have one, so not sure what the differences
> are between the various revisions.
>
> Adding the capacitor seems to have corrected the "my TDM card goes
> out to lunch about every two weeks, and the only way to correct it
> is to reload the drivers or reboot the machine" problem.
>
> Trying the following will likely void any digium warranty.
>
> Remove the TDM card from the PC and look closely at the pins associated
> with the four fxs/fxo modules. The pins are labeled on the modules as
> 1, 2, 19, and 20. The "reset" line is pin #2 while ground is pin #20.
> Carefully solder a .02 ufd capacitor between pin #2 and #20 on one
> module. Solder it onto a "single" module; no need to add one for each
> module. Install the card and boot up. Nothing more to it.
>
>> Also, when the driver is loaded, my system reports an E/F card, but the
>> board clearly says "H". Anyone know for sure which is correct.
>
> Best guess is the driver reports the E/F based on the pci controller
> ID, which may or may not have been changed when revisions to the
> physical card were made. (That guess can be verified by checking
> the code; I remember seeing it, but don't remember which file.)
>
>> As illustrated by the problems this card has with PCI slots. Even some
>> motherboards which clearly are PCI 2.2 can't see the card in ANY slot.
>
> Yes, but the flacky pci bus issue is a motherboard problem that
> really has nothing to do with the digium card design. (The pci bus
> issue is fairly well understood by those involved with heavy audio
> apps. It just so happens to impact how the TDM card is used as well.)
>
>> The FXS module is configured as a ground start device to provide dial
>> tone to an EM switch, as well as an inward path. Multiple FXS modules
>> would allow multiple connections, and GS is normally used to prevent
>> GLARE, or head on collisions on the outside chance that several calls in
>> and out occur at the same time.
>> Digium support person #1 has stated that GS does not work  on this
>> module, and support person #2 says " it should work"  In fact it does
>> provide a GS trunk that works well for outgoing calls. On incoming
>> calls, the module does not behave properly, in that before ringing
>> begins, Tip should be grounded, and stay that way throughout ringing and
>> answer. In fact, Tip seems to float somewhere during the ring cycle, and
>> providing an external ground causes ring voltage to cease but not trip
>> ringing.
>
> That's kind of weird as the Ground Start pin on the chipset isn't
> wired to anything whatsoever. The SI chipset apparently supports GS,
> but the circuit board traces don't. Guess it might be possible to
> _emulate_ GS through software, but its obvious the emulation isn't
> the same as the real thing.
>
>
>> Also dial pulse detection seems very narrow, and different dials that
>> work fine with much other equipment is not so with this card.
>
> The dial pulse sensing would be something done in the drivers, so
> sounds like that routine has the same narrow operating margins
> the echo canceller has.
>
>> >Trying to follow the code path for a functional TDM card is not
>> >to be taken lightly. Code is scattered across multiple drivers
>> >and buried in asterisk modules. Even those that consider themselves
>> >good asterisk developers stay way from this one.
>> >
>> >
>> That doesn't bode well for any corrections, does it.
>
> Nope.
>
>
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