EpsilonRho wrote:

I am having sporadic problems with DSL. I have established that the source
of problem is the phone line, because I have connected two different laptops
directly to the AT&T outside box in order to bypass the house wiring
completely and the problem persists with both PCs.



I called the AT&T customer service and the technician confirmed that the
line was unbalanced (squirrels chewing on the wiring). To solve the problem,
he just swapped the old pair with an unused one. The situation has now
improved somewhat but still the reliability is not 100%.



To satisfy my curiosity, I loaded the phone line (again bypassing the house
wiring) with one 2Kohm resistor. The measured loop current is ~15mA (well
below the range of the max. REN load). I was expecting to find a symmetrical
voltage change at the TIP (RED) and the RING (GREEN). To my surprise the
TIP voltage dropped from 0V to � and the RING voltage went up from �5V
to �30V. Obviously the line is totally unbalanced.



Is my assumption correct that the line should be at least DC balanced when
referred to ground?



TIA,

Gene



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"Those who cannot change their minds cannot change anything." - - - George
Bernard Shaw
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"Scientists study the world as it is; engineers create the world that has
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I had some trouble with my ATT DSL which stemmed from 1) Need for
filters on all phone jacks in the house. ATT put a master filter outside
in the NIC box to isolate all the old wiring. This helps. 2) I am at the
16,000 + distabce from the CO so my line is a compromise. 3) Some of my
old wiring was loose and shorting where it left the NIC. Still not 100%
perfect but more reliable.

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money" ;-P