atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems Troubleshooting help, please?

OK,

So here's the deal. As most of you know, I have 2 incoming CO lines. There's 7303 & 3942.

At some point (it may have been there from the beginning, I do recall making a post about a noise showing up and thinking it was caused by my alarm system) a noise started showing up on 3942. Don't quite know how to describe it, sort of a high pitched, very steady noise, present on 3942 at all keyset locations. You don't really notice it at all over the dial tone, but once you start dialing, you can hear it. It's not so loud as to make the line unusable, but just loud enough to irritate me.

I went down last night and hooked the buttset to the CO terminals. I then started pulling clips from the blocks, starting at the end of the chain and working my way back to the KSU, on line 3942.

Finally the noise went away when I pulled the clips from the first feed point to the 66 blocks, coming from the KSU. So my first attempt was to replace the cross connects going to, and coming from this point.

I Put the clips back in, and the noise was still there.

I then went up and diconnected the 2 keysets that were fed from that group of 66 block terminals... and the noise was gone.

Then I plugged one of the keysets back in. Noise comes back.

Unplugged it, noise went away.

Went to the other keyset location, plugged a keyset into it. Noise comes back. Unplug it, noise goes away.

Basically if I use a keyset on either of the cables supplied by the same group of 6 terminals on the 66 block, the noise appears.

Here's where it gets stranger. On the off chance I had 2 bad keysets, I grabbed a third. Same results as above.

Grabbed a fourth. Noise goes away, or at least so I thought. It went away from 3942..... but shifted over to 7303.

It was about 1:30 AM when I gave up, but a couple other things I did try was to repunch the 2 keysets at the block, which wasn't a lot of fun, but I managed to get enough slack to do it. The only place I haven't repunched is the KSU. Over the course of the night I also swapped out line cards, killed power to the intercom, disconnected the Melco C16, and removed the MOH and tuner cards.

I don't see how puchdowns could be the problem, since all keysets work fine, with no noise, as long as I don't use either of the 2 afformentioned keyset feed lines.

Any thoughts on the next troubleshooting step?

It's driving me nuts. Right now I just have them both unplugged and everything is fine on all keysets.

Thanks!
Matt

Addendum -

The problem persists if the KSU is powered up or not.

Also, thinking maybe I was running too close to a power line somewhere, I killed the mains.

Problem remains.

This is going to sound pretty basic, but go over the 25pr terminations to make sure they're not flipped. And look at the black/orange and black/brown pairs with an incandescent lamp! If no joy, check the connector end. I have had 1, and only 1, 25prFF with the pairs landed wrong. The factory DOES make mistakes. If both ends are flipped the same, no problem, UNLESS you cut the cable and punch it down or put a new head on it. John C.

Will do John - I've never looked closely at a connector end - do they follow the standard pattern?

Thx
Matt

Matt, also make sure that the last three violet pairs from each of the 2565's are not connected to anything unless you are using them with 4A speakerphones.

OK Ed - will do. Fortunately I'll only be using the TAM with the spekerphone, so tha makes it easy.

Thanks guys -
Matt

Yes, the connectors follow standard color code. BUT, remember that a pair is split between the left and right side. And now you know why white/blue is '1' and blue/white is '26'!

Well,

John -

Black/Orange and Black/Brown pairs look good, but I don't know if they are reversed in the connector.

Ed -

The last 3 (actually all) of the violet pairs dead end at the 66 blocks, with the exception of the 66 block where the 4A terminates, and it's fed on the 24th pair on only that block.

There's definately some sort of strange relationship between these 2 25 pair cables though.

Maybe another clue, I'm thinking of just ripping them both out and repunching.... but before that, I thought I'd throw this out there.

As I mentioned, plugging a keyset into either of these cables produces noise on all the other keysets. HOWEVER..... the 1 keyset plugged into one of the two 25 pair cables works fine, no noise at all. This is true for both of the cables in question.

I also removed all the clips for lines 3, 4 and 5 from the CO block. No luck.

Even with an incandescent, it's hard to tell the colors sometimes, as only a portion of the wire is visible. I think my next step is going to be to ohm out each terminal on the CO black back to the KSU, to verify nothing is backwards.

Will let ya know ... meantime ... as always ... open to any suggestions.

Thanks!
Matt

Not at the block, in the sets. Make sure the violet pairs are not laid down on the terminal strip, you need to insulate the spade tips and clear them.

Thanks Bill -

Will do. But on that subject - if they dead end at the block - why does it matter if they're connected inside the keyset? I'm not doubting you, just trying to understand.

Oh - Thanks John!

Thanks
Matt