comments on these troubleshooting specs and methods?
comments on these troubleshooting specs and methods?
Looking into the phone line with on-hook phone, you should see a 48 to 58vdc, the equivalent of four lead acid batteries in series being charged.
Off hook, and assuming 48vdc, the series resistance of the line should be approx. 470 ohms to 3200 ohms, depending on how far you are from the central station, with a loop current of 14mA to 70 mA, giving an off-hook line voltage of 3-15vdc.
There's Tip (red wire, -) and there's Ring (green wire, +).
The ringing signal is 35 to 120vrms at 16 to 60 Hz.
http://en.wikipedia.org/wiki/Ringer_equivalence_number
Currently, when it rains my phone gets static and goes dead. Since it's intermittent, unplugging the Network Interface Device gives me confusing results, plus I get to get rained on along with my plug-in phone and VOM. The off-hook line voltage goes to 0.8v.
After disconnecting the telco I ran the house phones on a 50vdc supply in series with a 600 ohm resistor, and this said the house phones work.
It all works now, probably due to a far-uptream repair that the telco made, but they're supposed to come in a few days to check my house.
I haven't tried it yet, but putting a 10 ohm resistor in series with the line and, off-hook, measuring the voltage across the resistor will tell me the current.
Therefore, from the inside of the house and from the current specs above, I will know if this 0.8v is due to the downstream house phones loading down a good line, or the upstream line being shorted out by moisture.