51-AL/151-AL to 685A subset

[Sargeguy]

I agreed to replace the line, subset and handset cords on a 51-AL Frankenphone (did not realize it was a frankenphone when I agreed;

The phone was a 20-AL that had a repro dial housing attached and the transmitter and receiver "upgraded".  The dial is a 5H.  The subset is a 634 housing with a 425B network clone inside.  The phone had a 5-conductor cord on it, I only have a 4-conductor.  Like a 51-AL there is only one terminal.  I strapped the dial and the network.  How should I proceed?

Here is what it looked like when I got it:

[Phonesrfun]

The key is in the hookswitch.  If it has three leaves and not 4, you will be left with it needing to be wired as a sidetone, and use 3 wires in the cord to the subset.  If it has 4 sections you can wire it for antisidetone and use 4 conductors in the wire.

The 425 network that is in the subset was probably wired with the 5 conductor cord, which is what conventional wisdom would have you do.  However, there is a way to wire a 425 network with either a 3-conductor (sidetone) or 4 conductor (antisidetone) configuration.  There are easy wiring diagrams that were placed in this forum a few years ago that cover that situation.

As for the connecting points in the base of the phone, you will probably need more terminals.  I know of at least one person on this forum that has sent me some of those authentic ones that clamp onto the base supports.  If you don't care whether it is authentic or not, you can probably get a two-position terminal strip at Radio Shack and file it down to fit inside the base and just let it float around or secure it with a wire tie.

I will try to search for the easy wiring diagram I am referring to.

[Sargeguy]

This is the one I have been using:

[Phonesrfun]

Yep, that's the one! 

[Sargeguy]

And this one from TCI:

[Phonesrfun]

The one from TCI is with a 684 subset using a 101A induction coil.  It seems that your subset, at least according to the photo has put a 425 network in place of the 101A induction coil and the associated capacitor.  You will need to use the easy diagram that shows the 425 network to wire yours up, or put a 101A induction coil and the associated capacitor back into the subset.  I can never remember the number on the dual capacitor.  (Same one that is in a 302....maybe 194A....  I don't remember the exact number)

Inside the phone, the TCI diagram is correct if your phone is a 151 with the 4-leaf hookswitch.  4 wires out on an antisidetone.  Red, green, yellow, and black.

[Phonesrfun]

BTW, that's a big honkin' biasing spring on that ringer.

[Sargeguy]

I am using the TCI diagram for the switch & dial connections, but have decided to use the 51-AL diagram to make things easier.   The 20-AL was actually a 20-S or 20-B converted to a 20-AL-it still has the 1,2,3,4 side-by side with the W,R, Y,YY,GN.  I need to translate these into BK, YY, RR, BB.  The huge spring was Dr. Frankenphone's idea

[Sargeguy]

I finally fixed it.  Next time I will "check under the hood" before I agree to something like this.