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Joined: Apr 2008
Posts: 5
Mark8 Offline OP
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Joined: Apr 2008
Posts: 5
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.)


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Joined: Aug 2003
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Joined: Aug 2003
Posts: 1,281
For quetsions 2. Answer: The cable modems would have NOT done any damage to your system if installed correctly. I've switch service for my customers all the time.

For questions 1: I don't know what the voltage that comes out of the power supply exactly. But I could tell you this. If you have acess to program the system. Remove all the cards except the main Processor card (MPD,MPD2 or Ipex) and try connecting to the system. If you can't connect, the problem is the processor card or the power supply. In rare cases it could be the cabinet.

Joined: Apr 2008
Posts: 5
Mark8 Offline OP
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Joined: Apr 2008
Posts: 5
Thank you very much for the information. I do not have the cable or software needed to program the system. Considering this, we decided not to attempt diagnosing the problem ourselves, but rather called a local phone technician come to our office this morning. He put in a new power supply, and everything works fine now. Thanks again,


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