atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems 1a2 hold lamp

Does anyone know why keysets come with a socket for a lamp on the hold button? Would this be for a message waiting lamp or some other kind of hotline? One of my phones has a neon lamp there and it was interesting to think what was it used for. Feel good though, i rewired 4 line cords that someone else cut off. Also does anyone know why a 2568 set has a relay in it and exclusion?

You could send ringing voltage to the hold lamp to indicate most anything like "Bring more hot coffee."

That was a class project I did back in 84. The "boss" would not want people listening in to his calls so dial tone would come from the tip and ring pair to his set and then back through the card to everyone elses phone. When he lifted the white plunger, that cut off that dial tone to everyone else and he could speak knowing that no one was listening on his call.

I finished that project early and as the instructer thought I was a smart ass, he said, "Well wire this phone to exclude that phone to exclude the rest. There's no print (diagram) for that smarty pants." I came in the next morning and wired it correctly much to his consternation. "Go read your newspaper and stay out of here." It was always fun pushing his buttons by doing something he thought you couldn't do.

You couldn't use ringing voltage on a 51a lamp and I don't remember using the hold button for that, even though there were/are lamps that would handle the ringing voltage. Seems to me it was used for exclusion, so everyone else knew that line was in use and excluded. There were a couple ways to do exclusion, one as Bunnie said where you pulled up the switch hook and excluded all other phones, the other phones were wired through the phone with the exclusion button as Bunnie said. There were also exclusion packs for the key system so you could have multiple phones with the feature and simply had to go off hook. I wish I could find my old 1a2 books, I'd look it up for ya. I'm sure someone on this board still has a set laying around, mine are ????? Somewhere?

We always used the socket under the hold button to store a spare 10volt lamp so when when running trouble tickets for dead lamps we also had spares at every phone. We always used the pull up plunger for exclusion. Did manage to unscrew the keeper machanism on one position so it wouldn't stay locked down and every time it was depressed it would light the lamp and give an audible buzz on several sets. It was kind of a "come see me button".

There were two formal uses for the hold button lamp that I recall. One was for a simple message waiting function which was operated by a manual key (switch) at another station. The second was for the exclusion function (white plunger button). My father's office had all 6-button sets and they wanted to add another line. All of the buttons were in use, so the Bell guys put the new line in the last button in place of intercom. To make an intercom call, they lifted the white plunger which gave them access to the intercom and the hold button was their intercom light. Seemed to me that it was an awful lot of work to avoid changing out the 25 sets to 10-button!

We used at one instance to light when a back door was open in an office.

It was also used for a individual busy lamp eg. the bosses phone would lite up on the secretarys hold button when he was on a line

If the bulb was a neon, they work on ring generator, and any use could be assigned to them, lighted from a switch or lighted from ringing.

You obviously could put a 10 volt bulb in there, but the poster specified a neon bulb so 10 AC volts or 24 VDC would not light that up.

Remember I know these things because I am OLD as it says below. OLD, as in when 1A2 was what most everyone had and if you were young then you are now OLD. I wish we had colors so I could put OLD in red.

OK so it means that when you get good at 1a2 you're old? LOL? I am really impressed that you guys can really remember this stuff! There's a remote exclusion circuit, wouldn't a relay be sufficient? It does seem odd to run the exclusion by routing tip and ring through one phone. Wouldn't it be better to just ground a wire at the set and control another relay? I am thinking of conencting the neon lamp to the main line of that set, and it comes from an Asterisk PBX and an ata, which has the message waiting function.

Yes, Rotary you could use a remote relay for exclusion, but remember that this stuff dates back to the Bell System days when it wasn't all driven by cost savings. It was also about quality and maybe that was the reason for wiring exclusion keys that way. They did it both ways, depending on the size of the job. If it was a simple one-station controlling all other stations, I guess it was easier to just do it through the set.

I think you are going to be hard-pressed to find a neon bulb that fits in a 51A lamp socket though. The switchboard neon bulbs were much longer in lentgh, about 1.5" as opposed to the 3/4" standard keyset bulbs.