PANASONIC KX-TD1232 CE - PBX hybrid - Dial tone problem

[sententia]

Re: PANASONIC KX-TD1232 CE - PBX hybrid - Dial tone problem

Longbow,

Thanks for the detailed info and guidance.

Troubleshooting flow charts in service manual do not apply for the problem i am facing but there might be useful information there. Only flow chart i think could be related is the "TOO MUCH NOISE LEBEL WITH INTERCOM (HUM). But even that (hum) indicates a constant noise rather a noise at specific time of dial tone.

Yes the noise appeared suddenly. The only strange thing was that it appeared first in the internal extension lines and after a bit on the expansion extension card. If you are talking about when the handset is picked up then also yes the noise i the instantly and constantly.
I haven't tried to dial an extension that is not used but i will get back to you with that.
You mention to scope "the digital line" coming to an extension phone. Are you referring to the analog extension line (if that is correct) or the DATA line pair wires which are used for the panasonic terminal phones? Anyway the problem is there for all 20 extensions phones ( Panasonic terminals using all 4 wires and normal phone is using only 2 wires).

When you say "distribution interface" do you mean the telephone terminal block distribution box? I had connected a phone at the equipment room with same results. However i still connected it to the "terminal block" and did not remove the wire pair from terminal block to connect it straight there. I will try that also.

Now as for grounding. The equipment room does not have a grounding bus. All equipment use their own power plug earth connection. The only thing that is not grounded is the metal distribution terminal block telephone box. But this was not grounded in the building that we moved out from and was working there for about 10 years. I do know i should have installed a ground there but skipped it as it was not connected from the professional technician in the first place. Anyway i am going to install that now just in case.

Unfortunately i don't have a dedicated scope however i use a sound card for that. Not the best option really but still better than nothing
I will have an update possibly today but nevertheless i will do further testing on site this weekend and possibly remove the PBX again.

Thank you for your time and advice!

[emiliovilla]

Re: PANASONIC KX-TD1232 CE - PBX hybrid - Dial tone problem

Just replace ic 6,7 and 8 on CPU.
Nose goes out.
Greetings from Medellin Colombia.

[emiliovilla]

Re: PANASONIC KX-TD1232 CE - PBX hybrid - Dial tone problem

Noise,sorry.

[sententia]

Re: PANASONIC KX-TD1232 CE - PBX hybrid - Dial tone problem

Respect goes to emiliovilla!

I confirm solution with noise that emiliovilla suggested fixes the problem.

Part number for ICs is MC145503P.

Thank you very much!

[Longbow]

Re: PANASONIC KX-TD1232 CE - PBX hybrid - Dial tone problem

Thank you, Emiliovilla. Looking a bit closer, it looks like these IC's are codecs which interface the CPU with the "outside world". Here is a data sheet on the IC's:



I noted the warning in the data sheet to keep i/o pins from swinging beyond the power supply rails. Operating as interfaces, the chips are likely to be vulnerable to external disturbances. I wonder if adding some TVS diodes or gas tubes near the transformers would protect the codecs?

It would also be interesting to know if all 3 chips failed, or if the symptom can come up if any one of them fails?

Interesting problem!

[sententia]

Re: PANASONIC KX-TD1232 CE - PBX hybrid - Dial tone problem

The very first problem with the PBX appeared after some water from an A/C dripped on the PBX and all 8 CO stop working and appeared busy. However at that time there was no other problem.

The noise problem was definitely evolving as first set of 8 EXT had the problem, after some time all other extensions had the same noise problem and in "hold on" music.

Now about the protection, there are some tube like components which i cannot recognize only on CO card. But these do not exist in EXT cards.

[budm]

Re: PANASONIC KX-TD1232 CE - PBX hybrid - Dial tone problem

Those are Gas discharge tubes.
I.E.
http://www.littelfuse.com/products/g...rge-tubes.aspx

[426]

Re: PANASONIC KX-TD1232 CE - PBX hybrid - Dial tone problem

...just chiming in with THANKS. Had this EXACT issue in double KXTD1232 cabinets. Replaced U6, U7, and U8 (MC145503P) - actually removed the chips, and put in sockets, THEN put in the chips - and the system is as clear as a bell.

Thanks to Sententia for posting the sound file, and thanks to Emiliovilla for the excellent solution!

There are 2 Panasonic KXTD1232s in Atlanta with renewed leases on life.

[Longbow]

Re: PANASONIC KX-TD1232 CE - PBX hybrid - Dial tone problem

This problem is obviously Panasonic's fault because they did not post a warning about spilling water onto the Codec board. 426, was your problem related to liquid spilled on the same pcb?

[426]

Re: PANASONIC KX-TD1232 CE - PBX hybrid - Dial tone problem

Nope...dry as a bone in there. Problem most likely caused by hard use over the last 20 years. Those cabinets don't owe me a dime, its been very stable for a very long time. We've got >50 terminals attached to those 2 KXTD1232s...

Interestingly, one power supply did fail, almost immediately after that, and being a live system, I had to improvise. I robbed a molex connector from an old KX-A46 (battery backup unit for the non 'd' KX-T1232), and wired it up to a couple of 12V DIN rail mounted industrial switching power supplies. The PULS 12V 10A supplies provide +/- 12 VDC to the 1232, and its been running that way for many days now. If anyone else does this, be very careful with the color code, because RED is NOT positive - in fact its like no other color code I've ever seen (goofy), and if you are not careful, I am certain it would SEVERELY damage the unit if it were wired up incorrectly.

[Longbow]

Re: PANASONIC KX-TD1232 CE - PBX hybrid - Dial tone problem

Thanks for the added information. I was curious about whether these chips are failing due to internal problems such as heat or power supply regulation, or perhaps external surges picked up by the output lines? Sententia did mention having a surge or power outage as well as the water.

[sententia]

Re: PANASONIC KX-TD1232 CE - PBX hybrid - Dial tone problem

Its been some time since last post but hey.....

I am almost persuaded that the noise problem and ic failure is irrelevant to the dripping water. On one hand there was not any obvious moisture sign on the CPU board and on the other hand that appears to be a very common problem with these PBX if they have been operated for many years. It sound more like a design flaw....

[Longbow]

Re: PANASONIC KX-TD1232 CE - PBX hybrid - Dial tone problem

Thanks for the update. It would be interesting to know the failure mode of these IC's is. I note from the data sheet that the input impedance is 10 Megohms! Dust or airborne contamination could easily settle on the IC and put the pins into an undetermined state, possibly exceeding the maximum dissipation of the chip. One symptom of this design screw up is if the chip does something different when you hook a 10Mohm meter to one of the logic pins. Glue under the IC could actually cause it, too. Then replacing the IC would fix the problem because the contamination would be gone making it look like the chip had failed. Stranger than life.

[ahmed hamada]

Re: PANASONIC KX-TD1232 CE - PBX hybrid - Dial tone problem

I confirm solution with noise that emiliovilla suggested fixes the problem.

Part number for ICs 6 is MC145503P.

Thank you so much! ahmed helmy from egypt . cairo

[ahmed hamada]

Re: PANASONIC KX-TD1232 CE - PBX hybrid - Dial tone problem

I confirm solution with noise that emiliovilla suggested fixes the problem.

Part number for ICs 6 is MC145503P.

Thank you so much! ahmed helmy from egypt . cairo

[DIDAKE]

Re: PANASONIC KX-TD1232 CE - PBX hybrid - Dial tone problem

One more small contribution to solving the problem
Start by removing only IC6.
When I say "removing" it is removing the integrated without replacing it.
The same work in the paging of the equipment (amplifier for announcements by external speakers)
MC145503P It also appears in the doorphone interface, if the equipment uses a doorphone interface, start by leaving the interface unconnected and try.