atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems Melco Intercom problems

I'm looking for help with a problem I'm having with a Melco KT-19, Bell Systems 55`C KSU and a 2851 Wall mount phone. I replaced a 2565 Desk Set (was working the Melco Intercom just fine) with the 2851 Wall mount phone. The 2851 receives buzzer ringing and voice path from Melco but the 2851 cannot buzz other phones. The weird thing to me is that I can hear the Melco box relays switching when I go off-hook and when I dial extension numbers.

Any ideas on what I am dealing with is appreciated.

Press one of the keys on the pad and listen. You should hear two distinct tones instead of a peep. I'm guessing that the new phone as a polarity dial and you need to reverse the tip and ring on the intercom. Quickest way is at the MDF where the phone is connected to the KSU.

Carl

He said "I can hear the Melco box relays switching when I go off-hook and WHEN I DIAL INTERCOM NUMBERS."

That is ambiguous. If he hears relays OPERATING when he dials, then there is another problem.

Carl has a good point. You need to be sure that the dial is actually transmitting correctly.

We need to have you to answer the following:

Do you hear actual Touch Tone signals in the handset when you dial on the intercom?

Can you take your test set, and monitor the T & R of the intercom circuit while you dial on the 2851?

Do you hear tones?

Did you use the same cable/connector for the 2851 as you had been using for the 2565? In other words, was it just a plug-n-play swap? Was the 2565 a Western Electric phone, or some other brand? Does the stamped model number on the base of the phone indicate that it was equipped with a polarity guard?

Is the 2851 able to dial out on POTS lines correctly?

Once we have these answers, we can continue.

Thanks for your help. Back working on this again.

Yes I hear Touch Tone signals in handset when dialing and on test set. Tones sound good to me.

2851 didn't have connector so I punched down wires. POTS and everything else working properly on2851 except Melco signaling of other phones. I can access Meco line on 2851 and all other phones on system have lines light up. I can have a second person pick up Intercom line and we can talk. Only problem is just 2851 will not buzz other phones. If I put back the 2565, it works fine.

If you hear tones in your test set, while monitoring the ICM line, but the ICM unit doesn't signal the other stations, there is a problem either with the dial or the ICM unit.

Does the dial on that phone work when you make calls on the outside line?

It's hard for me to understand what's going on, because you need to understand how all of these parts work, and you have presented us with a lot of contradictory symptoms. I was GOING to say the following, but your answers still do not make sense to me.

From what I understand, you have an earlier version of the 2851 that does not have a 25-pair connector inside, but has a small 66-type connecting block. (You didn't answer the question about what manufacturer made the 2565, but we'll get back to that if the following doesn't fix the problem.)

There are two ways to correct the problem, which is a polarity reversal on the T & R of just the intercom talk circuit. You need to find the pair of wires that feeds the 2851 ICM T&R and reverse them at the KSU or at some convenient wiring spot closest to the KSU.

--OR--

You can just go to the 66 block inside the 2851 and find the pair of wires that represents the T&R of the ICM talk path. If you are using the last (5th) pick-up key for the ICM, the pair would be the 13th pair (BLK/GRN - GRN/BLK). Disconnect that pair from the connecting block, and re-terminate it in reverse. (Swap the two leads)

In the event that you are using some other key for the ICM, the other T&R combinations for that phone are as follows:

Line 1 W/BL - BL/W
Line 2 W/BR - BR/W
Line 3 R/OR - OR/R
Line 4 R/SL - SL/R

Let us know if reversing the pair fixes it.

Failing that, give me a call between 9 am and 9 pm any day on 631 - 749 - 0100 and I'll try to walk you through this.

"Sounds good to me" does not equal precise DTMF tones needed for the Melco to work properly. But, as Arthur wrote, some of your statements don't make sense. While Central Office POTS lines are a little more forgiving regarding the DDTMF precision, it still does not make sense that the proper number dialed is reached on the POTS lines and the ICM does not function.

When you wrote that you can hear relay activity when you dial on the Melco, that may indicate that some of the tones may work or they are close enough to another tone to be recognized as a digit out of your extension range.

Rcaman