Partner Plus line noise

What can cause line noise on all extensions of a Partner Plus system? A friend has one and asked me if I knew, I know nothing about these systems. He says the noise is not on the CO lines and it goes away if he pulls the processor card.

I told him to just buy another system on ebay but he really would like to try to fix the one he has.

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J Kelly
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How can he tell the noise goes away if he pulls the processor card? The phones would go down, too.

Take care, Rich

God bless the USA

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Rich Piehl

I get the feeling he knows about as much about the system as I do.. He called me wondering what I know, only phone system I have ever worked on was a Panasonic.

So what your saying is that the problem could be almost anything, backplane, processor card, or line card? I think he is going to try to find another on ebay and then troubleshoot the one he has to figure out what he can salvage as spares.

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J Kelly

Could be that the Partner Plus is so old, that the 206 cards are NOT

206-E (expansion) cards. Pull the processor, and with 2-206's you've got a "baby-partner", where the 206's had a limited amount of processor power in them.

Anyway, if they are noisy with the processor installed, go to an ACS R6 or R7, use the 206's as expansion modules (until they eventually and surely die), and replace the carrier as well, as the new ones have more spacing between modules for better heat dissipation.

Reply to
Touch Tone Tommy

What kind of noise? How does it manifest itself?

Anyways, his first move should be to verify if the carrier is properly grounded and so is the power outlet that feeds it. Even if there is a ground wire coming out of that box, it does not hurt to verify if it is actually connected to the ground on the other end, and how exactly: I did see quite a few of those "corner cutting" installs where the ground wire is just thrown up in the ceiling, preferably not to be seen from the phone system location.

I have just returned from a site where the customer complained about cell phones inducing noise on the Partner sets. Turns out the system was plugged into a non-grounded outlet (they simply cut off the third prong!) and the ground wire was missing. Grounding solved the problem, so it may be the solution for your friend, too.

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I've personally fixed a lot of Partner modules, both processors and line card modules.

One of the other posts was correct in that some of the 206 modules contain their own processor, and so these are capable of some "basic" functions all by themselves, without needing a separate processor module. In other words, one of these 206 modules all by itself will work as a very small system (2 trunks, 6 stations).

Now, for the noise issues:

Each partner system module has its own built-in AC power supply. Because these are located at the top of each module and the cooling is very poor due to the thick plastic housing, these power supplies run HOT.

As a result, the electrolytic capacitors in them dry out. Once this has happened, either there will be a lot of noise (often a "hissing" noise) or the module won't work at all. When the power supply is the source of the problem, there will be a hissing noise in ALL of the station ports.

Repairing the partner modules usually consists of locating and replacing about 5 or 6 electrolytic capacitors in the power supply. Any electronic technician who fixes computer monitors or DVD players is probably familiar with "dried out" electrolytic capacitors. This is one of the most common failures in AC power supplies.

Also check the large circuit card in the 206 modules. There is a row of medium sized electrolytic capacitors in the area of the 6 station ports. Sometimes these leak electrolyte all over the large circuit board. This causes one or two of the station ports to have crackling noises or to completely stop working. Cleaning the circuit board and replacing the leaky capacitors often solves this problem.

Since the power supply runs directly on AC power, replacing the electrolytic capacitors is only recommended for those who are skilled in general electronic repair and PC board level unsoldering and soldering. But the cost of the 5 or 6 capacitors is probably under $10.00. These are readily available from places like Digi-Key.

Some of the Partner modules also contain a nicad "backup" battery. These allow the system to retain all the installed settings during power failures. Often these batteries go bad. If your Partner system loses all of the programmed settings after every brief power interruption, then the battery is bad. The battery is soldered in, so again some electronic technician skills are required for a "do it yourself" fix. Note that this battery is NOT intended for "long term" backup. Losing power for more than about 24-48 hours will result in loss of all the programmed settings even if the battery is good.

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Thanks for the good info. I'll have him check the caps. He is very handy fixing all sorts of electronic stuff, but knows nothing about this phone system (nor do I), he's the computer tech so they assume he can fix the phones too, and maybe he can with this info,

He mentioned to me that he doesn't know what the processor card does, or why its even there, and thinks it is the source of the problem, so maybe he can safely pull it and run with out it. I think its a pretty small office so he likely needs only basic functionality from this system.

Reply to
J Kelly

It turns out his system doesn't work with just the 206 modules. He just emailed me and said he bought a processor module on ebay and it came today and has fixed his noise problem. Maybe with your info he can troubleshoot the old one and have a spare.

Reply to
J Kelly


My best guess is that the power supply in his old Partner processor module has some dried up caps and is putting out noise on its +5 DC output. Besides using a "ESR meter" to check the power supply caps, an oscilloscope can be used to check the various DC output lines from the power supplies. All outputs should be nice clean DC, without any high-frequency hash or ripple at the power supply switching frequency.

I don't think any analog audio signals go directly through the Partner processor module. The only "analog" input on most Partner processor modules is the RCA-type line input jack for "music on hold." But I think even this gets turned into a digital signal before it leaves the processor module.

I know that inside the Partner 206 modules each of the 6 station lines has its own "CODEC" (CODEC = combined a-d and d-a converter, similar to in a computer sound card, but with only 8 bits of resolution in PBX line cards). Also, the 2 trunk lines in a 206 module each have their own CODECS.

So, once inside the 206 module, everything is in the digital domain for the actual switching and routing. Still, a large enough amount of power supply noise on the main +5 volt line in the processor module could turn into audible hiss in the telephone sets, as this might cause "jitter" in the digital signals.


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