atcomsystems.ca/forum Forums TDM Business Telephone Systems NEC Telephones & Systems SL1100: Static on CO line

Got a customer with an SL1100 with 4 CO lines from Spectrum hooked up to the system. Line 1 has noticeable static when on a call with a system phone. Other lines appear to be ok. I tested line 1 with my butt set by isolating line 1 and connecting to the spectrum demarc. No static. So far I've run program 90-68-01 (reset). I've also measured loop current which was at 39ma, on the high side. Aha, I figured, I'm onto something. Contacted Spectrum who didn't know what loop current was but will dispatch a tech tomorrow to, I guess, twiddle their thumbs. Contacted NTAC who advised lower gain in 14-01-02 and 03. They also advised I lower codec in program 81-07-01 from 0 to 1 (reset). It helped but static is still there. my next step I guess is to pad the lines, but if I do what size resistor would be needed. Does anyone else have any theories on this?

Did you move line one to another line port to see if it follows?

Have you tried moving line 1 to trunk 2? If the static moves to trunk 2 I would have Spectrum look at their settings or replace their equipment.

This is off topic, if you haven't already un-check 14-02-24 for each trunk. This is a known issue with cable equipment and only cable equipment causing conversations to cut out.

I'll do that....thanks for the tips

Ok, I'll ask a crazy question. What's 14-02-24? I don't see that code in the manual.

14:02:24 Found in SL2100 programming. Reference Analog trunk setup. call waiting,,
You are working on the SL1100 correct?

O, I'm working on an 1100......with an old manual. Just went on the NTAC website and downloaded the latest and sure enough, there it is. I guess this is where I wipe the egg off my face.

A side note, I just installed a brand new SL1100 and ever since the install, customer was complaining about audio on calls cutting in and out and even reports of the far end hearing a tone or beep once in awhile. I tried everything I could think of (short of replacing the KSU) and could not replicate the issue consistently. I opened a ticket with NTAC, and they immediately said to uncheck 14-02-24 (which is call waiting caller id) and is on by default. I informed them that the customer does not subscribe to call waiting on any of their lines, but NTAC was insistent that I give that a try. I disabled that on all three of their lines, and to my amazement, the problem has disappeared. I'd sure give that a try, it can't hurt.

Good to know for future use. The resolution to this issue was something else, and I'll admit something I overlooked. Line 1 went dead the next day. Tested ok at the demarc, but was dead at the tail which plugs into the SL. Switched to a spare tail. Line is up, static is gone. *dope slap*

Sometimes it's the simple things. With connections like CO's or Stations always trace a problem from a known good point to the point of failure. But you know that, right?