Modem won't hang up any more!
alt.comp.hardware, alt.comp.periphs
As of two weeks ago, I can no longer Internet-connect the usual way, via my Supra Express 56k modem. (My OS is Windoze98.) Here's the problem: I need to unplug and replug the telephone line going to the modem, to restore the dial tone. If not, the phone line remains open, so I can't receive or send phone calls. It's as if the modem lost its ability to hang up. (Problem remains even when my computer is shut down...so I know it's not OS--or even computer--related.) Now, when I don't need to get on the 'net, I unplug the phone line from the modem, and plug it into the back of my answering machine... which then allows me to receive and make regular phone calls. Is this a burnt-out modem chip? Or can I possibly restore my modem to its former excellent condition? Where do I start? I have yet to find the appropriate help file. If you know of one, please direct me to it. Otherwise, I'd much appreciate someone guiding me through possible maneuvers to correct the error. TIA. |
"Chief Thracian" wrote in
message om... alt.comp.hardware, alt.comp.periphs As of two weeks ago, I can no longer Internet-connect the usual way, via my Supra Express 56k modem. (My OS is Windoze98.) Here's the problem: I need to unplug and replug the telephone line going to the modem, to restore the dial tone. If not, the phone line remains open, so I can't receive or send phone calls. It's as if the modem lost its ability to hang up. (Problem remains even when my computer is shut down...so I know it's not OS--or even computer--related.) How many phones do you have plugged in in the whole house? They all add up and eventually cause problems. Try unplugging a couple phones and see if the problem goes awa. Now, when I don't need to get on the 'net, I unplug the phone line from the modem, and plug it into the back of my answering machine... which then allows me to receive and make regular phone calls. Is this a burnt-out modem chip? Or can I possibly restore my modem to its former excellent condition? Where do I start? I have yet to find the appropriate help file. If you know of one, please direct me to it. Otherwise, I'd much appreciate someone guiding me through possible maneuvers to correct the error. If it's broken, it's most likely a stuck relay. If it's just a normal relay, it should be easy to replace. |
Yours is a classic problem created by transient from AC
mains. Common mode transient sought earth ground. Incoming on AC wire that makes direct connection (through motherboard) to modem. Outgoing to earth ground via phone line. Since the surge was so minimal, a PNP transistor that drives off hook relay is permanently shorted. To get phone line free, remove phone line from modem OR remove power to computer. Second condition must be true if this is PNP transistor problem. Modem can be repaired by soldering a new PNP transistor between modem controller IC and that off-hook relay circuit. Your failure suggests no 'whole house' surge protector was installed on the most common source of lightning damage - AC electric. Lightning found earth ground via your modem regardless of whether you had computer powered. Even worse, a plug-in and adjacent surge protector makes this type of damage more probable. Chief Thracian wrote: As of two weeks ago, I can no longer Internet-connect the usual way, via my Supra Express 56k modem. (My OS is Windoze98.) Here's the problem: I need to unplug and replug the telephone line going to the modem, to restore the dial tone. If not, the phone line remains open, so I can't receive or send phone calls. It's as if the modem lost its ability to hang up. (Problem remains even when my computer is shut down...so I know it's not OS--or even computer--related.) Now, when I don't need to get on the 'net, I unplug the phone line from the modem, and plug it into the back of my answering machine... which then allows me to receive and make regular phone calls. Is this a burnt-out modem chip? Or can I possibly restore my modem to its former excellent condition? Where do I start? I have yet to find the appropriate help file. If you know of one, please direct me to it. Otherwise, I'd much appreciate someone guiding me through possible maneuvers to correct the error. TIA. |
Your failure suggests no 'whole house' surge protector was
installed on the most common source of lightning damage - AC electric. Lightning found earth ground via your modem regardless of whether you had computer powered. Even worse, a plug-in and adjacent surge protector makes this type of damage more probable. Even worse, a whole house protector on the AC would not have made a bit of difference if the lightning came in through the phone line. It still would have found ground through the PC just the same. |
Phone lines typically have a 'whole house' protector
installed free by the telco. If a destructive surge was incoming on that phone line, then 1) lightning would have to bypass a higher and more exposed electric lines to get to phone line, 2) 'whole house' protector for phone line was not installed or homeowner compromised the protectors all so critical ground wire, or 3) home did not provide / use a single point ground. So many reasons why phone lines are rarely source of surges and why AC electric is source of most surge damage. AC electric is the one utility that typically has no protection - especially if using plug-in surge protectors. Fax, portable phone base station, and modem damage usually is from a surge incoming on AC electric. Of course. Most every home is still wired as if the transistor did not exist; no 'whole house' protector on the most common source of destructive surges - AC electric. Even worse, many older homes have disconnected earth grounds. No earth ground means no effective protection - no matter how many ineffective plug-in protectors are installed. Phrederik wrote: Even worse, a whole house protector on the AC would not have made a bit of difference if the lightning came in through the phone line. It still would have found ground through the PC just the same. |
w_tom wrote in message ...
Phone lines typically have a 'whole house' protector installed free by the telco. Thanks for your helpful input...likewise, to everyone else who chimed in. I kinda thought this was NOT a problem that could be software-corrected (such as add ATH to the modem redial command string). I've gotten a lot of years out of this fine modem; and consider myself lucky that my system has suffered no other surge/spike damage in any other component. I live in an OLD building (built 1904) with old circuitry. Spikes are frequent, due to the elevator (the original!)...and I do use a Backup-UPS battery that allows me up to five minutes to shut down. In reply to Phrederik, who asked how many phones I use: just one...so the problem is simple to isolate. I believe I have experienced a short in the modem: a common experience as others here have explained. But not from lightening, which is rare in my neck of the woods (San Francisco). Thanks again, everyone! |
An old story from early days of computers. New computer
would not work. Tech ran diagnostics all night. Computer never failed until he left to get coffee. It got so bad that he would loudly announce his thirst and stomp out of the room. Then sneak back and peek around the corner. Still computer would not crash - until he actually came back with coffee. Eventually problem was traced to how one elevator was grounded. Everytime he took that elevator for coffee, it crashed the computer. Wonder why some people believe in ghosts? Who would have guessed how important grounding must be understood? Chief Thracian wrote: Thanks for your helpful input...likewise, to everyone else who chimed in. I kinda thought this was NOT a problem that could be software-corrected (such as add ATH to the modem redial command string). I've gotten a lot of years out of this fine modem; and consider myself lucky that my system has suffered no other surge/spike damage in any other component. I live in an OLD building (built 1904) with old circuitry. Spikes are frequent, due to the elevator (the original!)...and I do use a Backup-UPS battery that allows me up to five minutes to shut down. ... |
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