Does anyone know of a reason that can cause high voltage on analog ports? We are getting 148 volts when measuring the voltage at the TN punchdown. This is on an older 81 running rls 25.
I'm not sure how wide spread the issue is. We only found out because there was an issue with one elevator phone. I will be going to the site tomorrow and will check the voltages on other shelves. This is a DC powered PBX. Thanks for the replies.
What I meant about AC or DC: When you measure the voltage at the TN punchdown, is it 148 volts AC or 148 volts DC.
On a TN with message lamp/message waiting, you will see both AC and DC voltages. Example: when a phone rings, it is 90V AC. When it is idle, it is 48V DC.
The voltage is DC at the TN. It is almost system wide. I checked analog TN's on multiple cabinets and found the high voltage on most but not all shelves even within the same cabinet. This is an old 81C with the 8 port line cards. The rectifiers were replaced about six months ago. I'm not sure but we might have had the issue then but never noticed it. I also noticed on a few of the TN's I checked that the voltage was constantly fluctuating from between -116 to -148 but most of them were constant at around -144. It doesn't seem to matter if there is a station built on the TN or not. Still get the high voltage.
And where did your meter last test correct voltage? First it was just analog, now it is system wide. Do you know the pinouts of 8 port cardss Did you measure the input voltage to the system itself?
It's a DC system - that means you have batteries. Do you ave batteries?
Over 110 volts standing on an analog port is VERY hard to believe. Yeah, maybe when it's ringing, and only for a second, but all the time??? You should be smelling a foul smell and see SMOKE! Those cards should be glowing or melting. How old is that meter? Do you hear any loud humming (and not a woman!). Is this a DC system with a ground wire hanging in the breeze? Are yo sure you're in the right place? Let us know.
DocVic
Dedicated to Nortel Products till the end.
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