sundance-communications.com/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems Strange problem with 551C and 2565

The good news is that it is nearly impossible for the A-leads for each line button to be altered since the five wire terminals reside on a strip. Unless this strip is mutilated, that part should be fine.

What you need to do is to look at the orange/white wire from the line cord (the only needed A1 lead). It should be on a terminal to the right of the left dial bracket, paired only with the yellow lead from the switch hook. I cannot remember the designation of this terminal for the life of me.

You might also check the amphenol on the end of the phone. Your W/Or pair is on pins 27&2 (Or/W is 2) see if they look damaged. I've seen that before.

Sam

Well, I previously wrote that I was having trouble getting my 2565HKM to play nicely with my 551C. I noted that on ring the light would flash, but on pickup it wouldn't go solid light and on hold it wouldn't work either.

So I hooked up my 2851 and the 2565. When the 2851 goes off hook the light on the 2565 lights. When on hold, flutter is applied on both phones.

So it's A-Lead control that's messed up on the 2565. Because if I place a call on hold on the 2851 and then pickup that line on the 2565 the light on the 2565 is still flutter and the interrupter still engaged. So apparently there's something preventing A control on that phone.

I'm checking A -lead conductivity on the 2565 now. Hopefully I'll be able to fix it.

It gets deeper. I did probe out and found that A/A1 probe out to pins 2 and 27 on the amphenol and I get solid conductivity right back to the 66 block.

But I've narrowed it down. It appears something on the line switch is messed up since if I use a probe to trigger A/A1 for line 1, it seizes the line and lights the lamp. And if I momentarily pulse an active line it'll go into hold condition. So my next guess is something in the switch is messed up.

Would this be caused by the 2565 being wired for exclusion? That's my WAG. John C.

The wired for exclusion, is there any outward manifestation of that feature?

Here's a little more info. If I pickup line 1 on my 2851 it turns the lamp on the 2565 to the on state. If I pickup the 2565 the lamp remains lit. But if I put the 2851 back on hook the line immediately goes into a hold state.

I checked the voltage on the A/A1 pair for line 1 on the 2565. I get a solid 24V. Don't know if this is normal or not. I do know though that if I jumper the A/A1 leads I can get the line indicator to illuminate and if I just tickle it with the jumper I can trip the line into hold state.

So it narrows it down to something on the key switches. At this point I'm totally lost.

If it is wired for exclusion, you'll see an extra switch hook mechanism attached to the mounting of the original one. You will also see leads from this connected to the violet/blue and violet/orange pairs (These would be the most likely used pairs).

Yes, you should be reading about 24 volts DC across the A/A1 pair.

Ok, one thing I'm a bit foggy on is how the hold function works in theory.

Someone had described it to me many years ago and it made sense then. But I don't remember it so well.

I know A Lead control has the 24V across active line but what does the hold key do to it? I know it releases the line key and I see the switch contacts on it but have no idea what they do. I think that's where part of my problem is because I mentioned earlier I get a ground hum when I depress it.

When you go off hook, two sets of contacts in the phone close. One set shorts the appropriate A leads, then a split-second later, the other set cuts through the phone line. When both sets are closed, a call can be made and the line is lit steadily.

If the A lead short is broken while the phone is off-hook, this will place the call on hold. Pressing the hold button breaks the A lead connection long enough to start hold and then to release the line key on its way back up.

The line card detects the fact that current is flowing through tip and ring, but something caused the current flowing through A and A1. In detecting this, it places a hold bridge across the line and changes the lamp from steady to winking.

There's your problem. You have the pairs reversed.