Posted By: John3 One port off hook - TDA50 - 04/17/19 11:52 AM
We have a TDA50 Panasonic system at my hardware store with mostly KX-DT343 phones. A few days ago extension 102 went blank, and on the other phones the 102 light is on. The phone works when plugged into other ports. I've tried power cycling the TDA50, and also I've unplugged the RK11 plug from the port 102 plug on the DLC8 card in the TDA50. The TDA is configured with two DLC8 cards, a DLC4 card, LCOT4 card, and DHL4 card. I have access to a new DLC8 card, could it be the card is bad and that's why the one port is staying "off hook"? I am hoping to solve this myself as the installer that sold us the system is no longer in business. Thanks in advance for any suggestions!

Cornell's True Value Hardware
Posted By: dans Re: One port off hook - TDA50 - 04/17/19 01:25 PM
You didn't say if you plugged the phone into port 102 at the MDF, if not do so, if phone doesn't boot up you have a bad port, if it boots up you have a jack or wiring issue.
Posted By: John3 Re: One port off hook - TDA50 - 04/17/19 02:16 PM
Bingo. I had tried some other combinations of swapping jumper wires and cables, but plugging the phone right into the port works. Thank you!
Posted By: Carl Navarro Re: One port off hook - TDA50 - 04/17/19 02:21 PM
In Panasonic digital, the absence of a phone will light the BLF. By default, the numbering starts at 101, so the extension for 102 is the second port in the system. That's the 2nd port, left to right, on the bottom row 4-port card (DHLC, black jacks).

So, as suggested, take the phone and a 4-pin line cord, and plug it directly into that port. If the phone lights, you have a wiring problem. You already said the phone works, so I'm guessing that's your problem.

Posted By: John3 Re: One port off hook - TDA50 - 04/17/19 03:11 PM
Ah, the absence of a phone causes a light. Good to know as that had me confused as well. With everything unplugged I just assumed then that the port might be bad since it remained lit. Thanks!
Posted By: John3 Re: One port off hook - TDA50 - 04/18/19 02:48 PM
Dumb question probably, but the phones require two pairs, right? One pair for data, the other for voice?
Posted By: Carl Navarro Re: One port off hook - TDA50 - 04/18/19 04:20 PM
Not exactly dumb, but here's the deal. in the digital HYBRID line card, by default, the center pins are analog (as in preprogrammed for 2xx extensions) and the 2nd pins are the digital signal. All this requires programming

Posted By: John3 Re: One port off hook - TDA50 - 04/18/19 06:09 PM
Thanks Carl. When I installed the Panasonic system in 2013 I remember I had to update some of the jacks since our old system required just two wires. I also had to do some crossover cables for the output of the TDA50 to our patch panel RJ11 jacks.

I am going to have to trace the line tomorrow, waiting for a tone generator to help with this as the phone system is in my hardware store which has wiring upon wiring in ceilings and beams dating back to 1974. We started with a system from IT&T, then later Southwestern Bell which was a real workhorse. We then went to an Alcatel which was overpriced and not very flexible for our needs. The Panasonic replaced the Alcatel system, and it's much more flexible and has stood up to the retail store abuse.

I have to assume that someone crimped a wire somewhere along the run from the phone to the main unit, so tracing it back will be my project tomorrow. If that doesn't work I will probably just make a new run (approximately 140') and be done with it. Just another abandoned wire in the rafters. smile

Posted By: jeffmoss26 Re: One port off hook - TDA50 - 04/18/19 10:33 PM
Nice to see you here John!
Posted By: John3 Re: One port off hook - TDA50 - 04/19/19 07:43 PM
Originally Posted by jeffmoss26
Nice to see you here John!

Hey Jeff! Small world.
Posted By: John3 Re: One port off hook - TDA50 - 04/19/19 08:05 PM
Not sure if I am making progress, but I at least have traced the line from one end to the other. We had this tracer kit in our tool kit:

I set it up in Scan mode, plugged into the jack at the phone location. I used the tracer and the tone was clear at the TVA50 end of the run. So at a gross level the line is continuous. Do I try testing each individual wire in the 2 pair (4 wire) line to see if one is loose or broken?
Posted By: Professor Shadow Re: One port off hook - TDA50 - 04/19/19 08:38 PM
It appears that if you set it to Network it would show all wires individual as per the products website. Test it on a known good cable first so you know what to expect.
Posted By: Carl Navarro Re: One port off hook - TDA50 - 04/19/19 09:44 PM
Well, if the cable is good, you only have the jack, the patch cords, or something stupid. Look at the line cords that make up the patch. Since it's the outer pair, is the cord maybe nicked? How about the "crimps"? Do the black and yellow wires seat all the way to the end of the plug? I had an 8-pin fall out in my hands only took about 3 weeks to find it.

Last, but not least, you could make up a jack with all the pins shorted on one end and meter out the conductors, looking for opens. I'd like to tell you that you can read the voltages on the pairs, but you can't. The voice pair has 38 volts DC, but the data pair doesn't settle. You can read the same 38 volts on one of the data pins to one of the voice pins, but that's not much.

Posted By: John3 Re: One port off hook - TDA50 - 04/23/19 09:54 PM
Just wanted to close out this topic and give everyone an update. After various tests I was unable to get a good connection through the existing wiring. There are a few spots where the cable may have been crimped, so I just ran a new line (120', but through an open basement stock area) and the extension now works fine. So now I have an additional new wire added to the spaghetti western in the rafters, but the most important thing is the phone works.

Thank you all for the suggestions and advice along the way.


Cornell's True Value
Eastchester NY
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