atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems 1A2 Trivia

This is a duplicate . So I will try t remove the original !

Ok , a little 1A2 triva on keysets . What had to be removed from the line key assembly to turn a line key into a button signal key "non locking" ? What pair on a 10 btn set was reserved/spared for a 10/18 volt ac buzzer ? Ed , I know you know ! :toast:

I know too teacher...I'll give others a chance though.

I know you know justbill ! Your beard , My beard , same color . You are just better looking !Let's ask a 3rd part question . Where was the buzzer typically screw mounted to on the telephone frame assembly ? Them where the days , when you had to actually crack the set ! No wonder I like 1940's B&W B Westerns and not American Idol ! :toast:

I'll bite.

I believe the answer is "remove a screw" to make it non latching.

For the buzzer, I seem to remember Ed saying once it was either the yellow/orange or yellow/green pair typically.

Don't know the answer to question 3 though.

1. Removing the locking key screw made the button become momentary, as in non-locking. Wrap them up inside the set with some electrical tape so that you will have them when the key is needed again!

2. Yellow-orange was the designated buzzer pair for 564/2564 (six-button), and 830/2830/831/2831 (ten/twenty button sets). Yellow-green was the pair used for the buzzer in 565/2565 (six-button speakerphone-equipped sets). I never understood why there was a difference.

3. The 8A, B or X-series buzzer was typically mounted beneath the left-hand dial mounting screw in most sets, although the early buzzers had two mounting holes and 83X/283X sets actually had plastic bosses in the base to allow them to be screwed down.

Just to play with your heads:

8A buzzers used 10 volts AC and had two blue leads;

8B buzzers used 18 volts AC and had two red leads;

8X buzzers used 105 volts AC (ringing voltage) and had two black leads.

I know the power supplies had 10 and 18 volt outputs (I have one here).

Was the 10 volt supply just for the lights and possibly an 8A buzzer?

The 18 volt supply for the relays?

Ed
I knew this post would bring you back from your "Vacation Fog" . The taping the screw within the set , in case the key changed ! Delineated Tech or Hack ! I :toast:

Nope. 18VAC was always used for buzzer signaling only, but not really much in the Bell System.

Bell companies in the United States pretty much used 10VAC for lamps, buzzers and the interrupter motor. Independent telcos using ITT, Automatic Electric and Stromberg-Carlson 1A2 (and likely others) may have used 18VAC for buzzers, but not for any significant reason.

Relays were operated with -24VDC ("B" battery). A filtered -24VDC source ("A" battery) was cleaned up enough to provide a clear talk path over manual or dial intercom systems.

DC power outputs on 1A2 were always negative, as in the ground was positive. This is the same with Ring (battery) being negative and Tip (ground) being positive on C.O. lines.

A little tougher question .
When using a "Diode Ringing Matrix" with 1A2 what direction did the Cathode point ? A bouns question . What component within the tel-set had to be bypassed ? :toast:

I am going to guess it doesn't matter which way the cathode points (since it's a half wave bridge) as long as they're all consistent.

As for the component bypassed, was there an internal diode that had to be bypassed?