Dec 182017
A text file explaining hand telephone wiring circuitry and conventions.
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A text file explaining hand telephone wiring circuitry and conventions.
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FONE2.DOC 4307 1974 deflated

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FONE2.DOCHand-phone wiring connections.

(When trouble-shooting your handphone, or swapping its components, the
following information may prove useful. Downloaded from the AIMS RCP/M,
this file was originally named FONE. I have reformatted it slightly.
--Roy Lipscomb)

Date: 14 May 85 16:04:49 EDT
From: *Hobbit*
Subject: Wiring
To: [email protected]

It's rather difficult to send out schematic diagrams to a network of
people using regular old ascii terminals, but since wiring inside most
fones is pretty standard, a description should do the trick. This
applies to *all* WE phones and ITT phones that use the standard
dial/ringer/network block/handset configuration. I've rebuilt lots
of these suckers, and can confidently say that they're all the same.

Everything basically talks to the network block. The network block
contains the ringer capacitor, the induction coil that handles the
handset, and very little else save some spare screw terminals. Left
to itself, the network block can function as a standard line load [it
looks electrically like a phone] when a line is connected across RR
and C. These are the inputs to the coil. The ringing capacitor is
indeed across A and K as someone mentioned. In addition, older blocks
have a smaller capacitor across F and RR, to decrease sparking across
rotary dial contacts.

Green and White: Earpiece leads. These connect to net R and GN
Black and Red: Mike leads. Connect to net B and R respectively.

Black and Red: To line. Connect to L1 and L2 [or wherever your line
comes in].
Grey and Grey/red [these may vary; they are the ''other two'' wires,
anyway]: Connect to net A and K. The circuit thus
formed runs from one side of the line to one ringer
winding, thru the A-K cap, thru the other ringer
winding, to the other side of the line. This
configuration has infinite DC resistance, but picks
up the AC ring voltage.

RINGER [ONE-WINDING, rare]: Connect the single winding [two wired] in series
with the A-K capacitor somehow, and this whole thing across the line
as above.

Blue and Green: Interruptor. Connect to net F and RR.
White [2]: Earpiece suppress. Connect to net B and GN if desired.

Green: + Line in. Connect to net F.
Black: + Line out. Connect to net RR.
Org/Blk: - Line in. Connect to net C.
Red/Grn: Output common. Connect to net R.
Blue: Output. Connect to net B.

*Note: the above 5 connections will give you a "bare-bones" dial
configuration without features. Features are mike disconnect, earpiece
suppress, etc., which are done simply by routing leads to these through the
extra contacts on the dial instead of directly. If you want the features,
modify the wiring as follows. If your network block doesn't have the S and
T terminals, you have an old one designed for rotary dials, and you'll have to
do kludges.

Move Handset lead at White to net S. Also connect Dial White-Blue to net S.
Connect Dial White to net GN. This routes the earpiece through the dial
switching mechanism, which resistifies the circuit on button press.

Move Handset Red to T. Also connect Dial Red to T. This completely disables
the mike on button press. Make sure Dial Red-Green is connected to R if you
do this mod!

You'll find many variants of this in different units; some configurations
switch both sides of the line, some only one, some switch out the ringer
when off-hook [which isn't necessary, really]. The following should work:
Yellow: Connect to net L2. This is where the line enters.
Brown: Connect to net C.
Green: Connect to net L1. This is the other side of the line.
White: Connect to F. This is switched line power to the dial and the
Red: Connect to R. This, with Black, is shorting earpiece mute.
Black: Connect to GN.

Green and Red connect to L1 and L2. Try one polarity; if the touchtone
dial doesn't work, then flip them. Rotary dials, of course, don't


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