On Thu, 14 Apr 2005 08:14:37 -0600 Rich Adamson <[EMAIL PROTECTED]> wrote:
> > I was following a discussion on this list about the TDM400P > revisions. > >It is my understanding that the current revision that one > should have > >is the Rev. H and not the E/F. I have not yet been able to > verify the > >rev stamped on the board, but zaptel is reporting that I > have the Rev. > >E/F. I just bought this card in January direct from Digium and was > >wondering if I got the wrong Rev.
> >somehow?? I have been having some intermittent problems but only > >thought it was my setup.
> >
I did some more testing today. I called Digium on 4/12 and they
suggested some things to try, like different motherboard, switching pci
slots, etc.. I did everything they asked, except for the mother switch
as I do not have a different one to put in the system at this time.
So, after all that, my ringing issue still persists. Too some
measurements from bot the card and my POTS line in both the on-hook
state and ringing state. I uses a digital multi-meter to make the
measurements on both. Here are the results....
TDM400P
Before slot change:
On hook idle:
43.8 Volts DC 0 Volts AC
Ringing:
0 Volts DC 56.4 Volts AC
After slot change:
On hook idle:
48.7 Volts DC 0 Volts AC
Ringing:
0 Volts DC 65.5 Volts AC
We can only assume the above represents a fxs module on the
card. Correct?
I would find it hard to believe that changing slots would cause
the on hook DC voltage to change from 43v to 48v. That smells like
a funcky voltmeter. Slots should have nothing to do with DC
voltage unless the module is simply bad. The AC (ringing) voltage
is reasonable, but again it should not have changed simply
because of a slot change; again, questionable voltmeter.
On my POTS line:
On hook idle:
43.8 Volts DC .013 Volts AC
Ringing:
50.5 Volts DC 93.9 Volts AC
The on hook DC voltage from all US telco's will factually be
in the 48v to 52v range. If their central office equipment produced
43 volts, they would have alarms going off all over the place.
Their alarms would trigger somewhere in the 46 to 48 volt range.
So, that measurement implies the voltmeter is not accurate.
The AC (ringing) voltage is well within acceptable telco limits
and can range from about 70v to upwards of 105v.
Could it bee that from the phone company they retain the DC offset
voltage while applying a ring frequency and as it appears on the TDM it
shuts off the DC offset when ringing starts. Could this be the issue
with those of us in the U.S. having ringing issues with the TDM's??
Doubtful that is an issue. The reason for saying that is the chipset
used on the fxo & fxs modules was manufactured by Silicon Labs, and
those same chipsets are used in other telephony equipment worldwide.
Silicon Labs is known for good to excellent products. If their chipsets
didn't function correctly, there would have been a large uprising a
couple of years ago when those chips were first produced. That
hasn't happened, and they don't have a lengthy chip revision history.
Asterisk code does not have any control over adding/removing the DC
component during ringing, so that's not an issue either. Doubtful
that adding/removal the DC component would have any impact on normal telephone sets, however there certainly could be funcky sets
that don't like that DC removal.
Given the number of postings relative to the TDM card lately, I don't
remember exactly what your ringing issue was. Could you remind us
without deleting the significant parts of the above?
Even though it is long, I will leave everything intact.
I have had a few issues with dropped calls when using the FXS to FXO connection. Not sure what the issue is with that. THe main issue I have is with the ringing on the FXS card. I have three differnt brands of phones and all three do the same thing. I might get two or three calls in where everything works fine. But then the next one will cause intermittent ringing one all phones and no data for caller id.
I have tried every combination of the phones I have that is possible. From only one of each type hooked directly to the FXS card to hooking the card to my internal house wiring and using various combos of the phones connected.
It almost acts like the phones are requiring just a hair more ring voltage to work properly. That is why I was testing the voltage levels. I will try and grab a different meter to test with.
The system is a PIII 933MHZ, VIA chipset and has a 500 watt power supply in it. So I don not think it is a power issue from the computer itself.
The reason I asked about the DC offset during ringing, is that on the telco side, I noticed that the offset remained even when ringing voltage was applied. On the TDM, it does not. In the manual for the chipset that someone sent me, there is the option to apply a DC offset voltage during ringing. Additionally, the telco side gives the 93 Volts AC when ringing where the TDM is only supplying the 65 AC as according to my meter. These tests were conducted several times to get average readings.
As far as the issue with DC voltage on the POTS line only being 43.8 DC, my guess was that is just an issue with voltage drop on the line because of distance between me and the CO.
If I need to answer anything else, please let me know.
P.S. - I do realize that that the chipset is a good shipset. I am just wondering if everything is setup correctly in the zaptel driver for the proper programming of the registers in the chipset to make it function within specs.
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