Franc Zabkar wrote:
On 22 Oct 2005 04:54:15 -0700, put finger to
keyboard and composed:


Franc Zabkar ?? ???????
On 21 Oct 2005 12:55:26 -0700, put finger to
keyboard and composed:

Ambient Ham chipset Modem ATI diagnostics OK.Disabled 'wait for dial
tone' and It dials but it cannot connect and after that it just
'arrests' the line; tried at&t1 in Hyper terminal-modem 'connects' at
115200 and spits some characters,

The AT&Tn commands test the data path to the DSP. They are not really
helpful when troubleshooting a DAA fault such as yours.

ath/h1 ok; checked line-around 50
volts but when modem plugged in, it goes to 13v,

If you are measuring 13V on both sides of the relay contacts, then the
relay is stuck.

desoldered MOV is ok
but low resistance measured at it's modem board contacts;bridge output
goes to darlington...?;

Yes, that's the loop current stabilisation circuit, or whatever it is
called. It would be on the host side of the relay contacts. If you are
measuring any voltage there, then the relay is stuck.

as mentioned-in or out of the PC when I plug in
the line first you can hear the dial tone &then after 1-2 min. modem is
holding the line

Change the relay, or at least desolder it.

-- Franc Zabkar

Please remove one 'i' from my address when replying by email.

Shouldn't I suspect the transistor i.e. the circuit feeding the
coil-looks like upon line plug-in voltage buids up gradually to switch
the relay.

The transistor is driven from the DSP chip which gets its power from
the slot. The relay's coil voltage also comes from the slot. No slot =
no power. If the transistor or coil are getting power from the phone
line, then you have a *serious* isolation problem.

Change the relay, or at least desolder it.

You mentioned OC-if it's only function is ring detection can
i remove it, though OC's input diode seems to be connected also to
relay coil...

OC = open circuit

-- Franc Zabkar

Please remove one 'i' from my address when replying by email.

Thanks again
checked the transistor driving the coil-ok as well as flyback diode
Seems defective optocoupler(OC) could be connecting line to the relay
even when modem out of PC?