modem line takeover?!

[Don Bowey]

The box contains a driver CD, a leaflet like 'manual' with none of that info,
a
piece of foam plastic and the pcb in an anti-static bag.

The pcb has TUV, CE and FCC ( but not an FCC id ) printed on it together with
what I originally took to be the BABT approvals symbol ( but possibly isn't ).

I suspect the above are bogus.

There's no manufacturers info anywhere but I recall that it was sold as
'Mentor'
brand.

I've an idea to report this. Maybe I'll give the company that sold it a chance
to replace it though ?

Graham

Even a soft-modem needs hardware. For example, my new HP computer has a
soft-modem and it works through a PCI card, and it is called a PCI
soft-modem. Among other things, it has the RJ11 physical connection to the
phone line. It is this PCI card that will have the REN and other FCC
required info.

I imagine some motherboards could have this functionality so that a PCI card
isn't needed, but whether it's a PCI card, or it's on the computer
motherboard, it must contain all FCC Part 68 and Part 15 info, or it won't
be in compliance with Federal Law.

If it will help, tomorrow I will pull the PCI card and see what info it
provides.

What are you using for a terminal program?

Don

 

[Jamie]

Looked at several Motorola SM56 modems an all have the same fault-non
infinite resistance at line jack which causes them to take over the
line once the line is plugged, so none of the telephones can be used!
Checked the MOV and it is ok and there is no relay on modem !(at least
not a box type, just few too many smd transistors doing smth?)
There is a diode bridge so the line interface is a 'dry transformer'
type.Once you disconnect the line and plug it back in, it goes free for
few moments...
What do you suggest I check, other than the optocoupler?( because I
think it has to be ok since the modem is actually working if I manage
to hook to provider in few seconds before it takes over the line)

hmm, maybe your line in your home is wired backwards and
the modem thinks it should be on line?
its been so long since i have even used a modem when DSL
came out.

 

[[email protected]]

If there is a transformer, then the DAA is probably dry, as you say.
Otherwise there would usually be two chips, one on the line side and
one on the host side, with two or three ceramic caps providing the
isolation.


The symptom you are describing is that of stuck contacts in the hook
relay. But then you say that there is none ...


The optocoupler is there to detect the ring voltage and to isolate it
from the host side electronics. There should be a 1uF 250V cap in
series with its input, as well as a ~10K resistor.


There has to be some way for the host side electronics to control the
off-hook/on-hook state of the DAA. Look for a hook relay, possibly
solid state. Otherwise look for any device that bridges the gap
between the host and line sides.

Can you upload a photo to your web space?

- Franc Zabkar

here are the photos
http://putfile.com/pic.php?pic=6/17113372064.jpg&s=x2
http://putfile.com/pic.php?pic=6/17113412857.jpg&s=x2

the big lower left transistor is equiv of 2n5550 so I guess replaces
the box relay,
I wonder if somehow it could be replaced with it

 

[Arthur Dent]

Even a soft-modem needs hardware.

Yes, I have this PCI card that's based on a Motorola 'SM56' Chip.

For example, my new HP computer has a
soft-modem and it works through a PCI card, and it is called a PCI
soft-modem. Among other things, it has the RJ11 physical connection to the
phone line. It is this PCI card that will have the REN and other FCC
required info.

It *should* have yes.

I imagine some motherboards could have this functionality so that a PCI card
isn't needed,

Correct but this isn't the case here. I've had an integrated mobo like that in the
past and it worked fine. This issue relates to a PCI card.

but whether it's a PCI card, or it's on the computer
motherboard, it must contain all FCC Part 68 and Part 15 info, or it won't
be in compliance with Federal Law.

Federal Law doesn't count for much in the UK. We have our own laws.

If it will help, tomorrow I will pull the PCI card and see what info it
provides.

What are you using for a terminal program?

I haven't used the terminal program in ages !

I want to use it for a dial-up PPP account to an ISP !

Graham

 

[Franc Zabkar]

Even a soft-modem needs hardware. For example, my new HP computer has a
soft-modem and it works through a PCI card, and it is called a PCI
soft-modem. Among other things, it has the RJ11 physical connection to the
phone line. It is this PCI card that will have the REN and other FCC
required info.

I imagine some motherboards could have this functionality so that a PCI card
isn't needed, but whether it's a PCI card, or it's on the computer
motherboard, it must contain all FCC Part 68 and Part 15 info, or it won't
be in compliance with Federal Law.

I don't think you will ever find a desktop motherboard with all the
modem bits on it. This is because each jurisdiction has its own
telecom authority with its own specific requirements. Imagine if each
and every motherboard had to undergo telecom compliance testing in
every country in the world.

- Franc Zabkar

 

[Franc Zabkar]

here are the photos
http://putfile.com/pic.php?pic=6/17113372064.jpg&s=x2
http://putfile.com/pic.php?pic=6/17113412857.jpg&s=x2

the big lower left transistor is equiv of 2n5550 so I guess replaces
the box relay,
I wonder if somehow it could be replaced with it

It appears that you may have a "Kobian Mercury HPI56MII Data/Fax PCI"
modem:
http://www.modem-help.co.uk/mfc/kobian.html#hpi56mii

The two 16-pin chips, and/or possibly the 14-pin chip, appear to be
the line side and host side pair/trio of a silicon DAA. The two
ceramic caps provide the data path and isolation barrier. There is a
protective gap in the PCB underneath them. The line side IC would
incorporate the function of the hook relay and signal transformer. The
host side IC would, among other things, provide the off-hook/on-hook
control signals. In many conventional transformer-based modems, the
loop current passes through, and is stabilised by, a Darlington
transistor. This may be the function of the 2N5550 (???)

- Franc Zabkar

 

[Franc Zabkar]

I haven't used the terminal program in ages !

I want to use it for a dial-up PPP account to an ISP !

Graham

A terminal program (eg HyperTerminal) is useful for troubleshooting
purposes. For example, most modems respond to diagnostic commands such
as AT#UD, AT&V1, AT&V2, AT#UG, and quite a few others. I believe the
SM56 is quite good in this regard.

- Franc Zabkar

 

[Eeyore]

A terminal program (eg HyperTerminal) is useful for troubleshooting
purposes. For example, most modems respond to diagnostic commands such
as AT#UD, AT&V1, AT&V2, AT#UG, and quite a few others. I believe the
SM56 is quite good in this regard.

Good point. Once upon a time I even knew a few Hayes commands.

Graham

 

[[email protected]]

Franc Zabkar је напиÑ?ао

It appears that you may have a "Kobian Mercury HPI56MII Data/Fax PCI"
modem:
http://www.modem-help.co.uk/mfc/kobian.html#hpi56mii

The two 16-pin chips, and/or possibly the 14-pin chip, appear to be
the line side and host side pair/trio of a silicon DAA. The two
ceramic caps provide the data path and isolation barrier. There is a
protective gap in the PCB underneath them. The line side IC would
incorporate the function of the hook relay and signal transformer. The
host side IC would, among other things, provide the off-hook/on-hook
control signals. In many conventional transformer-based modems, the
loop current passes through, and is stabilised by, a Darlington
transistor. This may be the function of the 2N5550 (???)

thanks for taking a look
One confirmation the chips you mention- mot6269352/4 are making up the
DAA
is the diode attached to its pins probably as flyback for the internal
relay.
I doubt the diode bridge is relevant since it should be located behind
the relay in front of (incorporated) transformer. The resistance at
modems line jack is few Kohms(Varistor desoldered) either right away or
in case of several other modems only after the modem(out of the PC)
grabs the line! ATZ/ATH/ATH1 report ok but do not release the line. I
guess somehow smth energizes the relay ..> - Franc Zabkar