Re: Weird modem problem

Stated was that a telephone line protector must be properly
earthed. Is your's installed and earthed? What is missing? Only way
to know is visual inspection. What must be may, instead, be missing.

Other sources of these transients include AC utility power
switching. We recently had a 33K wire drop onto a local primary
wire. That surge also that must be earthed before entering a
building. A surge that can overwhelm galvanic isolation inside the
power brick.

If a modem is hanging the phone line without power applied, then
either modem's relay is stuck closed or something else on modem's DAA
side has shorted. No power to create the problem means no PNP
transistor failure. Since power is not required to see it, then an
ohm (continuity) meter should locate the DAA (phone line) side short
immediately. Very few components are on that side of the board.

Also possible that a part has failed on its own - manufacturing
defects. If the 'free' telco protector is installed and earthed to
same ground as AC electric, then modem should never see more than 300
volts. 300 volts should not cause DAA damage. Is that telco
installed protector earthed to AC ground rod?

Best evidence is a dead body. Easy to discover what is shorting the
phone line since that failure exists even when modem is not powered.

On Jun 1, 1:32 am, Charlie Wilkes <charlie_wil...@xxxxxxxxxxxxxxxxxx>
wrote:
There haven't been any electrical storms recently. I'm in the Pac. NW
where they are fairly uncommon.
...

This is a laptop, with a power cube that steps the voltage down and
converts it to DC. How likely is it that a surge of electricity would
make its way through the power cube, through the computer, and exit via
the modem and phone line without damaging something else besides the
modem? And what would the source of this power surge be?
...

It also acted like a phone off the hook when the power to the machine
was completely shut off. When I get back to my primary residence, I
will open up this laptop and try to determine the nature of the problem
and fix it if I can.

.

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