Looking for help with a 1969 Northern Electric 3 slot touch tone payphone

[rglenn]

A technology museum curator asked me to try to get his NE 3 slot payphone working for museum display.  So far most everything works except dialing out.  The phone can receive calls and the receiver and transmitter both work.

My problem is, the keypad doesn't produce tones.  While a button is pushed, the dial tone gets softer but the dial tone is not broken.

I will upload some pictures.  Thanks in advance for any ideas.

Rick

[Jim Stettler]

Did you try swapping the red and green wires?
Early TT pads were polarity sensitive. Later pads used a polarity guard.

[Key2871]

Yes, I was going to say that. But my phone froze and tooted.
Also it could be a mis wire that's keeping it from working.
Or the dial is bad.

[rglenn]

Yes, I switched the red and green, no change.

[rglenn]

another observation, the dial tone gets louder after inserting a dime or quarter. 

[Key2871]

Well I'd say it's the dial, it's gone south.

[rdelius]

That is a semi postpay pay station. The dial tone and transmitter will increase in volume after coins are deposited.
try cleaning the tone pad contacts and see it it will produce tones.

[Key2871]

I don't know the number on that dial, but I remember northern tone dials were a darker grey. I have one from a northern business set, that could be wired into that, free just cover postage. The dial is new with documentation for connecting it up.

[rglenn]

Ken, that's awesome!  How would you like me to handle the payment?

[Key2871]

Sorry I meant to say send me a PM and we'll work it out.

Edit,, thanks Rich I'll let you know when I send it out.

Ken

[Stan S]

Rick
You might want to try this before you get involved installing an unknown Touch Tone pad.

1- Remove the front of the payphone.
2- Connect a clip lead to the screw that the orange/black lead coming out of the Touch Tone pad is on.
3- Connect another clip lead to the screw that the red/green lead coming out of the Touch Tone pad is on.
4- Using ANY PHONE, unscrew the transmitter cartridge and clip the other ends of both
clip leads to the transmitter contacts in the handset.
5- Push a few buttons on the payphone's tone pad. If no tones are heard reverse the
contacts in the handset the clip leads are attached to.
6- If you hear tones try calling a number using the payphone's pad connected to the
handset.
This will tell you if the pad is actually working or not.

I wouldn't assume the pad is bad. That's a postpay 3-slot that depends on polarity reversal
to function. Could be other problems with polarity in the payphone causing the pad not to produce tones.
See pictures.
Have fun!

Stan S.



See photos.

[Key2871]

Good to know, I knew someone would come in and give another idea to try. Thanks Stan.

[rglenn]

Thanks Stan, I'll give that a try.

[rglenn]

Ok, I followed the steps but did not get tones from the pad even when reversing the contacts.

I did use a rotary phone in step 4 which I assume was ok.

[Key2871]

Yes correct, you just need to verify that you get tones or not.