My company's Telrad 128/S60 system abruptly stopped working (completely dead), a few days after we switched from POTS telephone service to cable telephone service from our local cable TV company. I removed the Telrad power supply (#76-110-1601/2) and tested the voltage on J1 with a digital multimeter, and I found only fluctuating voltages in the range of 0-4 volts on the +/- 5V terminals versus GND. At the -48VA and -48VA I measure exactly 0 volts with respect to GND, EGND, and each other (I'm not sure which terminal to use as "ground" for -48V).

I'd appreciate anyone's help with the following two questions:

1. Do I have a bad power supply, or am I testing the power supply incorrectly?

2. Does anyone know of any incompatibility problems with cable telephony modems that could cause damage to Telrad phone systems? (Our phone lines are now provided by an Arris Touchstone model TM504G modem which receives data through a standard RG6 television cable.)

Mark