Hi,
I've been having intermittent problems with my external US
Robotics 56K modem (connected via serial port) under both
Windows and Linux (using KPPP). When there is a problem,
when I switched to the winmodem on windows, or use my apple
ibook modem, it was ok, so that rules out line problem
(caveat: I'm about 21K ft from exchange, so cannot get 56K).
The symptoms are as follows :
Sometimes it works fine. However, if there is a disconnect
from the ISP, then the following symptoms can occur : when I
try to connect, instead of the dial tone, the modem gives a
crackling sound, and then finally return with a No Dial Tone
Found. If I switch off the modem and leave it for a few
hours, it may come back ok. Most times, I have to leave a
much longer time (two or more days). Rebooting the machine
usually does not help in this case.
Sometimes it gives a Cannot Find Modem message without the
crackling sound. In this case, rebooting may come back ok.
However, sometimes they don't, and I have to leave it for a
few days before it gets back.
I haved used minilog in Linux (and HyperTerminal in Windows
but I seldom use windows). When the problem is a crackling
sound, AT returns OK, but ATDT has the same crackling sound.
I've tried to use ATH0, atl-A-Z and exit to reset but to no
avail. If the problem was not a crackling sound, then
minilog doesn't show anything, doesn't even seem to respond
when trying to connect to modem. Even with ATE1, nothing is
echoed. When I do an exit, it takes a long time before the
cursor comes back.
Does anyone know what is the problem? Seems like something
in the modem is bad and not resetting itself properly.
Thanks.
James.
James Lee wrote:
Try replacing the line cord from the modem to the wall jack. If the line
goes through any so-called phone line surge protectors, bypass that.
Plug a regular telephone set into the "Phone" jack on the modem. When
you are experiencing problems, pick up the phone and see what you hear.
If it sounds clear with the phone, but crackling with the modem, then
it's likely the modem interface circuit has been damaged. That would
require a replacement modem, or sending that one in to USR for service.
Unfortunately, Windows built-in modem diagnostics do not test the part
of a modem that connects to the phone line, just the part that connects
to the serial port or PC socket. Good luck.
--
Art Jackson W4TOY Owensboro, KY USA
Life is God's open book test. In order to pass,
you must open His book to find the answers.
