[net.misc] Some modems dont work on some lines

k9un@iwsl7.UUCP (07/28/83)

I have a Rixon Sangamo 1200b modem that worked fine 'til I moved to a new
office here at the labs. On my new data line, I can dial my phone, get
an answer and carrieer, but the modem refuses to recognize it (all the
usual signals like TR.. are ok). The modem works fine on other lines.
The line "seems" to function fine audibly. I also tried a DEC DFO3 modem
and it also doesn't work. Finally, I tried a Penril DCD modem and what da ya
know? It works! 
Any suggestions? Our local people who are in charge of these lines have no
t been very responsive. I seem to remeb=mber having a similar problem at
home on my apple with the Rixon modem.

						Wes Ague

rb@houxn.UUCP (R.BOTWIN) (07/29/83)

Most likely problem is polarity!

Try reversing the tip and ring wires (usually red/green pair)...

All other things being equal that seems to be the problem...

Some things are polarity sensitive (like older touchtone units).

	Rob Botwin
	ABI/BTL .....houxn!rb

horton@uiuccsb.UUCP (08/02/83)

#R:iwsl7:-10200:uiuccsb:9900004:000:486
uiuccsb!horton    Aug  2 00:44:00 1983

Re: Some modems dont work on some lines

I can recall an instance where a modem worked on one phone line but not
another.  A different modem worked on both lines.  Turns out the mysterious
modem used the black/yellow leads for some kind of "data mode" switch.
The telco installer had left the spade lugs loose inside the box and they
had shorted together (as I recall).  The other modem didnt even have the
black/yellow conductors in the cable.

   kurt horton
   pur-ee!uiucdcs!horton