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Posted By: marvf series 2500 western electric no dtmf tones - 12/08/13 01:28 AM
I have a WE 2500 phone that has quit working. I thought it was becuase the last phone tech from UVerse messed up my polarity, and the only old phone that is polarity sensitive is this phone. So I reverse the red and green again in the phone jack. Still will not break dial tone. I repeatedly pushed the hook to break dialtone and get a silence, then pushed the buttons, and there were no tones. Does this mean that the mechanism is broken, or that there is a polarity problem? I did plug another modern phone, not polarity sensitive, into the jack, and it works fine.
On the back of the touch tone pad, there is a set of contacts that move every time you press any button. There is a set that shorts out the earpiece so that you don't blow out your eardrum, and a set that actually turn on the oscillators. That set is probably no longer making contact (they may be touching, but have oxidized). You can try a non-lubricating contact cleaner spray, and perhaps a burnishing tool to gently clean them, see if that will make it start producing tones again. You can also install a bridge rectifier to maintain the correct polarity, no matter which way it is in the jack.
Posted By: marvf Re: series 2500 western electric no dtmf tones - 12/08/13 02:13 AM
I very much appreciate your reply, and I will try that solution. Also, if you could give me a bit of guidance about the bridge rectifier, how to obtain the right one and how to install it, I will try that. It's a pain every time I get a service man out who works on either UVerse or the POTS and doesn't worry about polarity since most modern phones are not sensitive.

Also, though not on topic, I see you're in Paso Robles. I was born in that town in 1944, and my parents lived at the time in Peachy Canyon, wherever that is. They told me it was very rural at the time. My father managed the local Karl's Shoe Store downtown, I think across from a park. This was during the war and Camp Roberts was hopping.
Look up "Polarity Guard". I've used match books to clean the contacts when I didn't have a burnisher. You might be able to fine a solid state dial which would have a built in polarity guard.
Does it make DTMF tones? If so, the polarity is fine. Make sure that you get BOTH tones. If it doesn't sound like touch tones
the switch contacts are messed up or dirty. It's also possible that the tone pad is off frequency. This can happen if the pot core coils
have been bumped or diddled.
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