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

Here are some pictures of the Busy Lamp Field I connected today. Note the organization of the numbers. I suspect this has to do with the capabilities of the dial intercom systems. What I don't understand is why the extensions 20, 30 and 40 are where they are. Who counts like that? And why skip 10 - 19?

Also, what the heck do you use to get the lamps out? Taking the lamp assembly out proved to be a real hassle and I can't believe that is the correct way to get to them.

And one final thought. Were there ever LED versions of this?

• Busy Lamp Field With Numbers On
• Busy Lamp Field with Numbers Removed
  
  
• Numbers Illuminated
  
  

You need a 553A lamp removal tool.

https://tinyurl.com/3d4xch

The numbers coincide with the wiring of a dial select intercom. "0" is the tenth contact on a rotary minor switch, as used in a 207-C ktu, and the terminal strip on that unit (and therefore the resulting color code of the connecting cable) has the zero-th code at the tenth terminal screw.

The first 4 numbers are missing because 1 is seldom used as a first digit on rotary intercoms, due to what the Bell System diplomatically refers to as "handset fumbling" (in other words, employees who are too lame or shaky to find the cradle on the first try, due to too little/too much caffeine) and 2, 3, and 4 are used as the transfer digits for two-digit codes.

Tim -

Two things:

If you can't find a lamp extractor, I seem to remember having tolerable luck with a plastic straw. You may have to ream it a little but you can push it over the top of the lamp and pull it out.


When I worked with Strowgwer (Step by Step) switches, we never used the digit "1" for a first code (either level 1 access or 1x, 1xx, 1xxx for extension mumbers)in the dialing plan. The reason was that when using a rotary dial, dialing a digit sent 1 more pule than the number dialed - example: Dialing 3 sent 4 pulses, dialing 9 sent 10 pulses, dialing 0 sent 11, Dialing 1 sent 2 pulses.

The reason? Picking up the hookswitch sent 1 pulse. If you had a hookswitch that had a little "bounce" to it, then just going off hook would dial "1". This would cause all sorts of dialing errors.

Because of a legacy of rotary phones, this dialing plan was kept up for years.


Sam

"The reason was that when using a rotary dial, dialing a digit sent 1 more pulse than the number dialed - example: Dialing 3 sent 4 pulses, dialing 9 sent 10 pulses, dialing 0 sent 11, Dialing 1 sent 2 pulses."

Sorry, Sam, wrong number.

Picking up a phone does not cause a dialled digit "1" to be sent. If it did, then every time any of us picked up a phone, the dial tone would go away, having been broken by the ROH.

Every Strowger selector or connector switch that I worked on only had ten levels and ten rotary positions. Dialling a 5 causes 5 interruptions to the loop current, resulting in 5 pulses to the switch train, causing the vertical pawl to move the switch shaft up 5 levels or the rotary pawl to move the wipers over 5 terminals.

I would be interested to have you provide us with the SD- numbers of any selectors or connectors that had eleven vertical levels and eleven horizontal contact positions.

(The eleventh rotary position, reached when all sleeves on a particular level are grounded, is without any T,R or S terminals, and a cam on the shaft activates the "eleventh rotary position" contacts, causing "Tone Busy" to be sent from bank contact #14 to the Tip side of the calling party's line through the A relay of the selector or the connector.)

The initial digit "1" was used extensively in S x S switches, in both subscriber-premise and Central Office applications, as the initial digit in PBX tie-line access codes (such as 112, 113, 114, etc) in the subscriber environment, and for toll-trunk access in the case of CO applications.

Handset fumbling in those applications, causing an errant digit "1" to be dialed, was not a big deal, because two or more subsequent digits would need to be dialled for a wrong number to be transmitted through the switch train, and called-party disturbance to be a factor. However, in a single-digit intercom, the fumbling would immediately result in a mistaken buzz to be sent to Station #1, causing the Boss to curse, and throw his cigar at you.

That's why, for instance, the 207C KTU had only nine SIG outputs, and why the digit "2" was used as the transfer digit, when installing a 216A KTU for more ICM stations, one of which could be "21".

Please hang up and try again.

Aurtthur, altough I find all the stuff about "steppers' fascinating,( Western Union made me a better offer than SWB) I think maybe you missed a line in Sam's post.
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The reason? Picking up the hookswitch sent 1 pulse. If you had a hookswitch that had a little "bounce" to it, then just going off hook would dial "1". This would cause all sorts of dialing errors.
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I can see the reasoning in his statement, only because the exact same problem drove me nuts with a Mitel SX100 and a bunch of defective 2500 sets of a manufacturer that will remain unamed. Hookswitch bounce can be a b--ch! John C. (Not Garand)

PICKING UP a handset does not make a pulse. It makes a connection. A pulse is defined as an open. Nothing opens when the handset is taken off the hook. The line is already open, and closes when you go ROH.

FUMBLING the handset might make a pulse, if conditions were right.

Reread what I said: If just picking up a handset makes a pulse, then we would never get a chance to hear the dial tone, as it would have already been broken, as the handset came up to our ear.

As I also said, show me the SD for a selector or a connector that reads two pulses as a "1" or nine pulses as a "zero" and I will shut up.

Arthur -

If I'm wrong I will stand corrected.

I came in to the business as SxS and X-Bar were on the way out. I never went to formal school on them, I was only field trained by other techs. If I learned erroneously, I apologize.

The explanation I gave is the one that the fellow that taught me Strowger switches gave me. Your answer makes a lot more sense, thinking back on it now. Hard to believe that nice old guy was so badly in error.

I do remember that when in 1979 or 80 when I cut the Bronx VA over from a WE 701 to a NEAX 31, NY Tel used dial "1" access from the stepper to us. I argued against it, but they had no spare levels to use during the interim. I had, as I expected, constant problems with locked up tie trunks and wrong numbers - all originating from the 701.

It was my understanding that this was caused by switch hook bounce "dialing" 1 and seizing the tie trunks and presenting the user with NEAX Dial Tone. Further dialing by the user (expecting a different condition) caused me no end of problems.

Sam

I worked at the BX VA 701, too. I was often the only Manhattan repairman on duty North of 59th Street, during the Midnight to 8 shift, on holidays. I was often sent north into the Bronx for an emergency PBX repair. Funny how peoples' paths cross.

What was the title of that movie? "Six digits of separation"?

"7 pulses of separation."