sundance-communications.com/forum Forums TDM Business Telephone Systems Nortel Telephones & Systems Loosing line position on LSDS

I thought I had this problem solved, but it has reared its ugly head again. About a year ago I had lots of trouble with a 0x32 6.1 system loosing a position on the lsds cards. All 8 positions were in use on this system. Over time, lines were lost in each card, usually on the same lines, but it varied enough to make it interesting. If I swapped out the lsds card things would work ok for anywhere from a day to several weeks before a line position would fail again.

During this time, I swapped in a loaner card that was quite old. This card never failed. When I would put in the permanent replacement card, days or weeks later it would fail. I suspect this is because the old loaner card was built tougher than a newly manufactured card.

Anyway, to solve this perplexing, and expensive, problem I installed everything I could think of after the standard telco demarcation protection. I have ITW Linx TowerMax CO8-110 protection on the phone pairs, going to ITW Linx UP2P-235 "avalanche protectors", going to a 330 ohm resistor (one resistor on each side of the line), going to the KSU inputs. The KSU's power cord is plugged into a UPS, which is pluggedinto the TowerMax surge strip, which is plugged into the wall outlet. All grounds are run back to the electrical panel.

There was a power outage over the weekend affecting the entire town. This system isn't close to the electrical substation. This morning one line position has no dial tone at the set (dial tone on the block is ok). Incomoing calls cause the sets to ring, but no one is there if answered. Caller hears ring no answer until they hang up.

On the lines block going into the ksu I have 52 volts dc. Incoming call ringing produces 102.4 volts ac.

I have two other systems across the street from this one, but haven't heard from them yet. They have a similar protection scheme installed.

I'm at a loss at what to do. :confused:

Thanks for any ideas.
Jim

is there any alarm codes

No alarm codes.

What about event codes?

Sounds like a TelCo issue to me. Line voltage? Ringing voltage? Resistance?

(But of course, they will blame you/equipment until they're blue).

can't remember all the details, but it seems like
we had the same problem a few years back and it
ended up the trbl was in the line card of the co
at the phone company.. they had a dms 10 switch if i recall and they ended up after a kazillion
calls replacing it and never had the problem again. just a thought.. cul the dinker.

i have had some problems like that also, the last time i went to site i set the co setting for the line to short co in line programing to account for high voltaged. Have not had to go back for some time now.

The co switch is a GTD5. The lines that have failed over time are on different co cards. Had that checked out a long time ago.

One switch tech confided to me last year, that he had seen a similar thing in another town. He mentioned the resistors on each side of each pair to accomadate for a "too hot" office. I mentioned it to a supervisor at telco that I know, to see if telco would pay for my bad line cards :rofl:

I hadn't thought about changing the co settings in the MICS. I'm just awful gun shy about putting another lsds card in. Presently I have the line shorted a the demarc so all calls are rolling over to line 2. Guess it's time to pull my head out of the sand and swap another card!

Jim

This issue sounds like a high line current problem. You've read the voltages, now read your current!

I read loop current, etc, last year with original trouble. As I recall it was in the green range. Don't remember exact numbers, but will check it tomorrow on site.

Wouldn't the resistors help with a high current problem? I'll get better readings and post back tomorrow.

Jim