Author Topic: READABLE diagram for Northern Electric 3 slot push button payphone.  (Read 842 times)

Offline tanderson78

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Re: READABLE diagram for Northern Electric 3 slot push button payphone.
« Reply #15 on: July 14, 2017, 06:17:41 PM »
I picked up a W.E. 2500 at my local Habitat for Humanity ReStore two weeks ago for $3.00.  The 2500 worked just fine.  The pad is a 72H3A dated 3-82.  Red, Green, Blue, White, Black, Orange/Black, Red/Grey, and White/Blue wires.  Even with the old pad from 1968 and trying 2 different hand sets, volume was very weak.  I swear I was able to get the 1982 pad to dial!  Plus, the diagram doesn't show what to do with the green and black wires.  And of course I tried swapping line wires for polarity.

Offline tanderson78

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Re: READABLE diagram for Northern Electric 3 slot push button payphone.
« Reply #16 on: July 14, 2017, 06:21:16 PM »
White/Blue was taped off.  I thought it was a substitute for Orange/Red.

Offline Stan S

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Re: READABLE diagram for Northern Electric 3 slot push button payphone.
« Reply #17 on: July 14, 2017, 06:52:34 PM »
A Western Electric type 72 Touch Tone dial is an integrated circuit pad. What was originally in your 2236 was a pot core pad. The colors of the leads coming out of the pad are different. Get a pot core dial.
Stan S.

Offline tanderson78

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Re: READABLE diagram for Northern Electric 3 slot push button payphone.
« Reply #18 on: July 14, 2017, 07:27:29 PM »
I have a few lying around but I think they need tuning.  I'm on the road at the moment, but the original dial was dated 1968.

Alex G. Bell

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Re: READABLE diagram for Northern Electric 3 slot push button payphone.
« Reply #19 on: July 14, 2017, 07:28:14 PM »
A Western Electric type 72 Touch Tone dial is an integrated circuit pad. What was originally in your 2236 was a pot core pad. The colors of the leads coming out of the pad are different. Get a pot core dial.
Stan S.
Even a pot core dial will probably not work just by matching lead colors because the original dial used the BL to feed the common R terminal of the NET to the receiver for switching inside the dial via the W lead, like early 7-lead  dials.  Most dials have 8 leads and switch the receiver via an isolated circuit consisting of W & W-BL.  Most likely the BL and W-BL leads of the dial will have to connect to R of the NET via the #10 terminal for the receiver to work.

Alex G. Bell

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Re: READABLE diagram for Northern Electric 3 slot push button payphone.
« Reply #20 on: July 14, 2017, 07:32:30 PM »
I picked up a W.E. 2500 at my local Habitat for Humanity ReStore two weeks ago for $3.00.  The 2500 worked just fine.  The pad is a 72H3A dated 3-82.  Red, Green, Blue, White, Black, Orange/Black, Red/Grey, and White/Blue wires.  Even with the old pad from 1968 and trying 2 different hand sets, volume was very weak.  I swear I was able to get the 1982 pad to dial!  Plus, the diagram doesn't show what to do with the green and black wires.  And of course I tried swapping line wires for polarity.
You cannot just assume that dials are interchangeable, especially if there are different lead colors, even if it worked in a different environment.  Even leads of the same colors may not function the same. 

IIRC, 72H3A dials contain a polarity guard. 

Dates are pretty much irrelevant.  Apparatus ID codes are all that matters.

Alex G. Bell

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Re: READABLE diagram for Northern Electric 3 slot push button payphone.
« Reply #21 on: July 14, 2017, 07:35:29 PM »
White/Blue was taped off.  I thought it was a substitute for Orange/Red.
No, W-BL is the input signal from the network to the receiver via the dial.  You cannot possibly hear anything in the receiver with the W-BL lead unconnected.

Offline tanderson78

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Re: READABLE diagram for Northern Electric 3 slot push button payphone.
« Reply #22 on: July 14, 2017, 10:39:48 PM »
I wonder why they kept the same wire colors but changed their function between pad models?  Did anybody every make a chart that cross references tt pad model numbers and wire functions?

Offline tanderson78

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Re: READABLE diagram for Northern Electric 3 slot push button payphone.
« Reply #23 on: July 14, 2017, 10:48:56 PM »
Anywhoo, incorrect pad and/or wiring aside, with the pad completely removed from the network and the DA15 wired per the correct diagram, I can barely hear the dial tone on this network, even after trying several handsets that sound fine on other phones.  I am half tempted to use both the dial AND network from the ReStore 2500 and put this issue to bed.  I didn't pay that much for this payphone and it's tough to expect every piece of 50 year old technology to work like it did from the factory.  Any other thoughts before I shoot this lame horse?

Alex G. Bell

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Re: READABLE diagram for Northern Electric 3 slot push button payphone.
« Reply #24 on: July 14, 2017, 10:50:58 PM »
I wonder why they kept the same wire colors but changed their function between pad models?  Did anybody every make a chart that cross references tt pad model numbers and wire functions?
It's just not that simple.  A telephone circuit is complex and a TT dial can be inserted into the circuit a number of different ways.  So cross referencing the leads assumes all phones have the same circuit.  They don't.

Alex G. Bell

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Re: READABLE diagram for Northern Electric 3 slot push button payphone.
« Reply #25 on: July 14, 2017, 10:52:47 PM »
Anywhoo, incorrect pad and/or wiring aside, with the pad completely removed from the network and the DA15 wired per the correct diagram, I can barely hear the dial tone on this network, even after trying several handsets that sound fine on other phones.  I am half tempted to use both the dial AND network from the ReStore 2500 and put this issue to bed.  I didn't pay that much for this payphone and it's tough to expect every piece of 50 year old technology to work like it did from the factory.  Any other thoughts before I shoot this lame horse?
As I said before, the receiver (and the transmitter) circuits pass through the dial.  With the dial disconnected those circuits are open so I'm surprised you hear anything at all!

Offline Stan S

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Re: READABLE diagram for Northern Electric 3 slot push button payphone.
« Reply #26 on: July 14, 2017, 10:55:03 PM »
The answer to your question is yes.
All the information regarding TT pads is in the TCI library. You just have to do the research.

The info below is courtesy of some very hard working TCI members.
Stan S.