TELECOM Digest OnLine - Sorted: Re: 1A2 Help Requested

Re: 1A2 Help Requested

Carl Navarro (
Tue, 10 May 2005 08:27:41 -0400

On Mon, 09 May 2005 18:16:36 -0700, wrote:

> TELECOM Digest Editor noted in response to the original query:

>> [TELECOM Digest Editor's Note: I can tell this much; no one,but no
>> one tampers with or tries to rewire the inside of a 1A2 phone. The
>> wiring is just too complex. All the rewiring is done in the box on
>> the wall where there is room to move your arms and fingers, _not_
>> in the phone itself. PAT]

> No doubt. No one ever changed the wiring within a 1A2 or 10A2 set, with
> the expection of installing a buzzer for intercom. But, that wasn't
> really rewiring; rather loosing a couple of screws to overlap
> u-connectors.

> And, no one in the field re-wired a 1A2/10A2 KSU, other than to
> restrap the tie down wiring to change features, etc.

> Ain't computers great?!

> TELECOM Digest Editor's Note: I really do not think anything much can
> be done inside those phones without a lot of grief that cannot be done
> better and quicker at the punchdown block on the wallI

The 10-button sets were the most fun, because you had tons of room.
True, most of the surgery involved adding things like bells, buzzers,
flash buttons and speakers, and removing screws from the keystrips for
signal buttons, but sometimes you had to field replace a keystrip,
tone pad/dial, or a network module. Or in the case of the last
Comdials, whole circuit boards.

I still may have some of those items in the corner of my warehouse

Carl Navaro

[TELECOM Digest Editor's Note: For a good time, try adapting a six-
button/five-line phone to use the little twist knob up in the left
corner of the dial plate for something or another. You know, the
little twist knob which (on a two line phone with mechanical hold)
would switch between lines when you lifted the plunger on the left
side of the switchhook. Many folks had those in their homes for two
lines, but they did not realize the twist knob actually had a _third_
position as well: turn it sideways or up and down to select the
desired line, but depress it as well (it was spring loaded and only
would stay down if you held it). On those phones, where red/green
in the cable was line one, and yellow/black was line two, the blue/
white was the third position output. Pressing down on that twist
knob was often times used to (a) ring an intercom buzzer manually,
or (b) apply ground as needed on a ground-start line.

Those little plungers built into the left side of the switchhook
had various jobs also. On two line phones with mechanical hold, they
were used to short the pair _not_ being used, to keep it on 'hold'
while you were talking on the other line. When the little plunger
was used as an 'exclusion key', lifting it up would disconnect all
the other instruments which were in series behind it. To make that
happen you came from the demarc in to that phone _first_, wired
it up, _then_ took the wire back out to the demarc and went to the
other phones on the line. I also sometimes saw the little twist
knob used to feed (or not) the operator headset jack built into the
back of the six button phones, and sometimes the little plastic
plunger in the switchhook was used to activate a monitoring line to
a speaker (or a combination speakerphone/monitoring unit). The
switchhooks of course are spring loaded also to make them pop up
and down, but the ones used in connection with twist knobs could
additionally be pulled up a bit further as needed.

And here is a good project with a two-line twist button phone:
Take a little neon bulb, the kind that only flashes when it gets
90 volts of current. Open the two line phone plastic case and mount
that neon bulb inside right next to the plastic twist/turn knob.
Attach the wires to one of the pairs. Now put the phone back together
and dial the number associated. Watch the neon bulb flash in
cadence with the ringing signal. If you get really cagey, you can
attach the neon in a way that when you are on one line or the other,
the _alternate_ line will feed the neon bulb, so that if you get
a second call in the midst of it, instead of a loud ring to disturb
you, all you will see is that twist knob blinking at you as the
_alternate, not currently in use_ line is 'ringing'. Sort of an
elegant 'beehive lamp' IMO.

I haven't had one of those two-line or five-line phones around for
many years. They can be such fun projects to work on, at least the
two-line phones. I wish I could find one around somewhere.

Trying to work inside the six-button phone itself was enough to make
any sane person go crazy, so you can imagine what it did to me. How in
the hell I got all the way to 1999 in my life without my head
exploding is beyond me. I was due for it years before it happened when
I contemplate some of the phones I messed around with. On the other
hand, at the inside terminal block, if you could say to yourself
'line, light, hold' over and over as you counted by threes down the
block in there, you had it made. PAT]

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