Centracom 7-Pair Cable Q's and DigiTAC tone keying problems

[d119]

I'm piecing together a Centracom Gold Elite from spare parts. Having some minor issues I think might be cable related.

When I start up the OP and launch Gold Elite, it connects to the CIE and says "Op not ready - Internal communications error".

The only way to clear this and get the OP to start up is to unplug the 7-pair cable from the back of the CIE or CEB, wait a few seconds, plug it back in, and everything is ready.

I didn't have a factory 7-pair cable handy, so I used a couple of cut off pieces from different equipment and wired it straight through, 1 to 1. Do any of the wires cross over from CEB to CIE or is it straight through? Seems like a reset line isn't working right or something.

The other issue I'm having is that when the console keys the DigiTAC during a conversation, they keying tones are heard over the air. I've tried adjusting the rekey delays in the DigiTAC, and it does get rid of the tones, but this leads to the transmitter dropping momentarily and then rekeying, causing an audio hole and loss of dispatcher audio for about 1.5 seconds. I've tried playing with jumpers on the Tone Keying Module in the DigiTAC (yes it's a DigiTAC, not a SpectraTAC).

Base station is an MSF 5000.

Thanks for any help.

Any ideas?

[wa6jbd]

No ideas on the Centracom Elite problem, but I've dealt with similar issues in the Digitac's. I had observed either intermittent dropped audio, or completely missing audio, and the alignment solved the problem.

In my case, the problem was improper decoding of keying tones from the console in the Digitac itself, and was resolved with a complete alignment of input and output levels. There's a factory alignment procedure that shows how to properly do that, if you don't have access to it yourself, I could forward it, along with a rewrite of the process that I developed that made it a bit easier to follow.

[Bill_G]

As requested, looking at your thread, and I don't have any ready answers for you d. I've had to put a cable stretcher on Centracom cables before, but I always spliced the wire color for color, not wired direct to the connector. Don't know off the top of my head if the pairs are straight through or crossover. I'll look it up when I get into the shop today. As for keying tones over the air, I'd start with levels. Since it sounds like all the equipment is in the same room, the levels should be -10 in and out.

[luisa.kmet]

Hi, That 7 pair cable needs twisted pairs otherwise you''l get crosstalk from the data to audio and vice versa. I have had customers wire 1 to 1 without the twisted pairs being correctly matched and get ticking noise on the audio due to the data bursts. I think if I remember correctly, the pairs go across the Amphenol connector.

Pair 1 <1 14 > Pair 1
Pair 2 <2 13 > Pair 2
Pair 3 <3 12 > Pair 3
Pair 4 <4 11> Pair 4
Pair 5 <5 10> Pair 5
Pair 6 <6 9> Pair 6
Pair 7 <7 8> Pair 7

Amphenol connector

[d119]

Turns out the solution to this problem with the "Internal Communications Error" and having to unplug the CIE 7-pair and plug back in to get it to boot was as follows:

Dip switch 8 on the COIM was set for "Classic" mode and not "Elite" mode. Once this switch was set properly, the system works fine.

Still getting keying tones over the air when the console rekeys during a subscribers hang time. I've set all levels properly and it's still doing it.

[d119]

Still getting keying tones over the air when the console rekeys during a subscribers hang time. I've set all levels properly and it's still doing it.

FYI I found the solution to this being that the HLGT level programmed into the DIGITAC was set to 0dBm. Setting it to -10dBm got rid of the bleed through. The overdeviated signaling was punching through the notch filter.