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Guys,
I have poked at the BSPs and I am not easily finding what I am looking for.
I have this: tone commander FL 2000 [Linked Image from i165.photobucket.com]
FL 2000 intercom light flashing unit I would like to hook up and I am good on all the connections but the interrupter start and lamp flash sources.
The 551B has MB and MG terminals on the block but not "motor start" like some other KSUs I have seen. I also have a 10V interrupter and its impossible to tell from this box if the interrupter start is 10 or 24 v
As for the lamp flash from the interrupter I suspect there isn't a pin for that on the connecting block and I would need to steal that from the bussbars on the line cards.

Anyone have some quick advice on this so I don't pop a lot of fuses???
I am unfamiliar with the unit so my first question has to be : what does it do?


Sam
Supposedly It hooks up to a dial/tone intercom and to each station signal output. It then has individual light outputs for each station. With those inputs when you go off hook and dial a station this box makes the receiving station light flash like a ringing line...
That's a pretty nifty device then. I've never seen one.

The 551 was a real low end 1A2 KSU and had a very small footprint and as such was missing a lot of the "extras". As I recall an easily accessible ST (interruptor start) lead was one of them.

I don't have a manual for the unit, but I believe Ed does and he should be along soon with the info on where to find it.

Most interruptors were 10 Volts. The 24 volt ones were designed for battery-backup /power failure where everything in the KSU ran off 24 Volts DC.

Sam
After a VERY quick perusal of the 551 BSP and 400D KTU BSP, I "think" that:
1) MB is motor battery, either tied internally to the 10v lamp supply or strap removed and manually connected to 24v for a 24v interrupter.
2) MG is the start signal, a brief ground will run the interrupter thru one cycle. (i.e., ground-to-start, regardless of motor voltage)
This is a flashing lamp unit to be adapted to one of Tone Commander's self-contained intercom units. It sure won't do anything by itself. It doesn't do much of anything except to add the flashing lamp on the intercom button function on a 1A2 (or even 1A1) system. I never understood the reason for this, especially due to the insane cost for it. My guess is that it might have been a requirement on government installations, though I've rarely encountered them in the DC area.

The base intercom unit still provides a single talk path and the traditional single or two-digit dial codes. The difference is that the FL-2000 causes the called station's intercom button to flash upon an incoming intercom call. Again, seemingly senseless to me, but I digress.....

The 1A1/1A2 KSU's interrupter (98% of them anyway) operates on 10 volts AC, the same voltage as the system's lamps.

The MB (motor battery) lead for the interrupter is this constant 10 volts AC power. MG (motor ground) is the ground for the return of this power (yeah, I know, there is no return path as in +/- with DC power, but stick with me).

The ST (start) lead is what starts the interrupter running through its cycle. As long as a system ground is applied to the ST lead, the interrupter will keep running. When that ground is removed, it will stop when it completes its clock cycle (my way to describe how it just returns to its home or stop position).

Oh, and all 551 KSUs have a terminal marked "ST" on the lower right-hand section of the block where all of the other power connections are.

You won't find much in the BSPs about Tone Commander products since they weren't manufactured by Western Electric, but there may be some local Bell practices out there that were developed.
Thanks for the detailed responses guys.
Ed you are right this is a totally superfluous doodad but I was curious to see if I could make it work just for coolness factor. For whom I dont know since everyone thinks I'm ridiculous with my "old phones" LOL

Regarding the start lead. I hate to disagree but my 551 only has MB and MG, there is no ST... But I wonder if it is there in the unconnected leads bundle on the door of the KSU. Otherwise I am sure I can find it at the backplane. Same deal with the lamp flash
Heres a pic of the 66 block with no ST... I was a bit confused about this myself since the BSPs show a couple of different punchdown legends and I had to double check.
[Linked Image from i165.photobucket.com]
Oh, man. I meant to say all 551C KSUs had it, which is what I assumed that you have. Stupid fat fingers.

You are correct; there is a sleeve of wires coiled up at the factory on the right side of the KSU and I think it includes the start lead, among many others. Let me look into this. The ST terminal was definitely right above those connections in the later versions. Earlier references for the start lead were
That's ok, I have a lowly 551b
In the spare bundle there are 3 pairs
Orange
Blue and
Green
I didn't explore them yet and see where they go
You're right. Those are just inputs to pins 3/18 of the card slots to provide field-wired talk battery for manual intercom card.

The ST, or MS lead from the line card slots is on pin #5 (common on all slots). The line card places a ground on this lead when a call comes in on a CO line. You can ground this lead anywhere within the KSU to start the motor running for its cycle. This pin is the same on all card slots.

My experience with 551 KSUs never involved any of the later generation add-ons, such as the FL-2000 and I apologize for sending you on a wild goose chase. I made the assumption that all 551 KSUs were the same.

Regardless, the MS or ST lead you are seeking is going to be found on pin #5 of any card slot in the KSU. You'll probably have to wire-wrap it on your own in order to land it and just punch it down on one of the vacant rows of clips on the 66 block above the MG/MB terminals. There are a bunch of them there that are unmarked.

No worries Ed, this is helpful.
I expected it would be mildly complicated anyway. I can source the st from the backplane

Is there a specific pin on the interrupter that provides flash? I was looking for a good schematic and have yet to find one.
Lamp flash is on pin #7 of any line card slot. Here's a block diagram of a typical line card that gives you some idea of what you need:

400D Line Card
this appears to be the best BSP for the 551's that I could find:

https://bellsystempractices.org/500-/518-/518-215-407-i01_1976-07-01.pdf
Thanks guys I think I am all set now. I know I had seen the card pinouts somewhere and for the last week I have been looking at KSU docs for it and it didnt dawn on me to look at the KTU docs which is the easiest place to find it. Ugh.

Thank you all for the help!
I jumpered the FL 2000 into the system and tied the lamp lead to one station so far to prove it works. Using it with a Melco KC19 tone/dial IC
The white set goes off hook and all IC lamps on all stations line 5 light, you select the called station IC number, in this case STA 4.
Station 4, Green set: Buzzer sounds and line 5 lamp goes from steady to flash until the station goes off hook. Once off hook the lamp goes steady and the interrupter stops at the next cycle.

Here are my thoughts... Its an interesting function and kinda "neato" for a collection system. However it requires a lot of wiring for such a simple thing that 99% of people wouldn't notice. Ill probably hook it up if I can get it to work reliably. I've noticed sometimes it doesn't seem to want to work the way I would expect it to so Ill play with it some more.
Thanks for all the help and advice. Heres a link to a youtube vid showing how it works:
"However it requires a lot of wiring for such a simple thing that 99% of people wouldn't notice."

Well it is kind of "neato", but it probably wasn't a big seller - and just for the reason you mentioned.

It also, probably wasn't cheap.

Sam
It's the electronic version of the original 6A intercom.
[b][/b]
Originally Posted by Arthur P. Bloom
It's the electronic version of the original 6A intercom.
Back in the mid '70s ITT had a 1A2 prep packaged system called the 36A. It was 1A2 with a 2 or 4 channel Intercom under one button with 36 or 54 stations. Flashing lights and bells and blah, blah.

It was a nice system and we put quite a few in, but I don't know how successful they were. Anyone else remember them?

Sam
I remember them, although I never installed one since they were extremely expensive.
Looks interesting.

https://www.frillfreephones.com/itt36aksu.html
Originally Posted by jeffmoss26


DRAT!, I clicked on it thinking you found one for sale!

Still, looks like a neato system.
Yup, that's it. I don't think I've seen one since 1975.

Good catch, Jeff!

Sam
Wow thats quite a beast.....
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