atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems 584C Panel Oddity

I've got my 584C panel loaded with 400E KTUs and powered by a WE 20B2 power unit. Power connections were made in accordance with this ITT Practice (PDF page 61):

ITT Practice

I've got the first Amphenol connector broken out to a 66 block, and I've got PBX lines connected for the first four 400E cards. I cross connected everything for the first line to another female Amphenol, to test with a 2564 phone. The CO/PBX lines were connected to my Legend. This is where it gets weird. When I push the first line button, the relays operate and the line light illuminates as it should. All I hear in the receiver is static/noise, and when I press a key on the pad, I don't hear tone. Pressing the hold button on the set doesn't do anything. I tried reversing both the station and PBX T/R pairs (separately of course), but still only hear static. I switched out the line card and also tried a Stromberg "baby Call Director" set, and still have the same issue.

Did I make a rookie mistake somewhere, or does my hardware have gremlins in it?

I don't have the patience to try to find the part that discusses the 584C panel, amongst 126 pages of practice, so I will just tell you the way to do it, and hope that you can understand without a diagram.

Before you do anything else, be absolutely certain that you have cut down the 25-pair cable correctly. Many installers in dim light confuse the colors, or split the pairs, or make some other mistake.

After you are sure that the cable is installed correctly, you simply follow the color code in groups of 5 pairs. Each group of 5 pairs is mapped to a CO line.

Blue = CO T&R
Orange = Station T&R
Green = A ground/ A lead
Brown = Lamp ground / lamp
Slate = Common audible ground / common audible

Plug a line card into (only) the first slot.

Use your test set and verify that you can hear the CO line at the blue pair of slot #1.

Verify that you can hear dial tone on the orange pair.

Verify that you can hear 24 volts unfiltered DC on the green pair. (or use a voltmeter)

Short the green pair, and verify that you can hear 10 volts AC on the brown pair. (or use a voltmeter)

If you can't hear all of these, you have a defective card, or you have a defective panel.

I'd check pins 14 and 16 on the line card slot itself (especially on the wire-wrap pins on the back) and see if they aren't bent and possibly touching or perhaps there is some debris between them. Pin 16 is your A lead and 14 is your CO side tip. If those two are somehow married, you'd get the noise you are describing and a non-functional hold feature.

Since you say you are getting your CO line dial tone from a Legend, that line's tip side is not grounded as a typical CO line would be. That would explain why pins 14/16 being in touch with each other are only causing noise and not closing the A lead. A real CO line somehow crossed with the A lead would cause the A lead to act as if grounded by the A1 lead, which is what happens in a normal situation.

As Arthur said, you really should check your white/blue and white/green on your punch down. White/blue is the CO tip and white/green is the A lead. If they are transposed, this would cause this kind of problem. Factory wiring rarely fails, but field wiring often does.

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