atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems Can you guess what this is?

I'm working on a little project to bring back a 1A2 gizmo that seems to be made of unobtanium these days. I have some custom made PCB's on their way to me, but they haven't come off the boat from China yet. Here's one I threw together on a piece of perf board. It is the exact same layout as the custom PCB I designed and almost a perfect copy of the original. Can anyone guess what it is and what it does?



I hastily pinned it to my backboard and hitched it up, and it works just as well as the original. I will be making 50 of these to start, and if anyone is interested in them, let me know. (obviously once everyone knows what it is)

Is this a solid state interrupter? I've heard that 118 ring generators are made of unobtainium these days, but it is way too many interface pairs for a ring generator here.

MCT66 is a dual channel optocoupler, so can be a lamp extender (but then I don't see any high power MOSFET to drive the lamps) or a line ringing detector. Anyway I ran out of my guesses.

Very good catch on the dual opto. The two opto's are paralleled. If I ran down what the conductors do, I'd probably give it away. Suffice it to say, it runs on B battery, the two transistors take one of those conductors to ground, and last hint, there's two pairs of series diodes (1N4005) across two of the conductors, each pair in parallel, but in opposite directions.

Anyone?

OK another hint. The leads are (in descending order) GND, A, RING OUT, RING IN, TIP OUT, TIP IN, B-Bat.

Rats...I was going to guess T, R, A, A1 LG, L, B1, R1

There's only 7 wires going in, Dean.

Note the lack of A1......

I botched the wht/brn lead and just extended it by soldering a little jumper.

Quick reminder, this isn't some contraption I dreamed up, it's a clone of a once common as dirt piece of 1A2 apparatus.

Well I'm older than dirt and I can't place it. Manual intercom's the only thing I can come up with, but no talk batt.

My first thought was a 400 card but not enough parts:

36-400-201 ITT 400E

The original was made by Melco...

If you can crack my code, I can crack yours

I suck at these things. I don't even know where to start or what I'm supposed to be looking for.

I thought it might be an exclusion unit.

That's the best guess by far, but still not it.

I thought someone would have gotten it by now.

Here's another clue. Sandman makes something very much like this, but it's not nearly as good. This device will trigger even if a call has been placed on hold, where Sandman's won't. (I know because I just used it to replace a Sandman unit.)

Ok. Since no one is biting, here's the PCB that finally arrived today. The printing on the corner should tell you what it is and what it does. It's a clone of a Melco device.

Never used them, just wired the set for control, unless I still don't know what it is.

This was used when you had a phone or device you couldn't rewire for A-lead control. Things like cordless phones, fax machines, and stuff of that nature.

I have my partner system behind my 1A2 system, so these work perfectly to give me A lead control when I'm on a partner phone, especially if I answer a call on a 1A2 set and place it on hold to take it on a partner set somewhere else. This will let me retrieve the call from hold on any other phone.

Super cool! Looking forward to seeing the result.

I don't remember ever wiring a fax behind a key system, doesn't mean I didn't. I remember banks of faxes with dedicated lines.

Excellent! I've got a Melco unit and a 6B I've used and they'll both light a lamp on the key system, but neither of them will take a call off hold.

I'd be interested.....

Sam

Sam, this is an exact clone of the Melco S64-1 A-lead adapter. If you have one of those already and it doesn't work, this may not help you. That being said, I'd be interested to see how you have them wired. I think it was customary to feed DT into these from the station side of the line card and when I wired it that way, it only partially worked. I got line lights and whatnot, but it refused to take a call off hold. The secret was to get DT from the CO side of the line card and then it worked fine. I have a regular POTS line, and three VOIP lines feeding my 1A2, and all four I can take calls off 1A2 hold as long as the adapter is wired on the CO side.

Of course, the more I think about it, there's also a chance that the Melco units that are out there are all pushing 30+ years old and the components have surely all drifted in value. They have three electrolytic caps on the board and those things age as gracefully as milk. So, maybe the one's I'm making with fresh parts might be just enough to work again..... Can't hurt to try.

One thing I haven't sorted out is packaging. It's just the bare board and a short piece of cat5. I could drill the corners, and with some standoffs you could just screw the thing to a backboard. My next iteration of these, I'll find some cost effective cases and design the board to fit them so it can be enclosed and pretty. The other thing I'd really like to do is find a board mounted 8P8C jack and design that into it so you can just plug it in. Dressing the cable and soldering it in is tedious.

Another thought I was having was making multiple adapters on one board. That way if you needed more than one it wouldn't eat up a bunch of real estate on the backboard.

Neat!!

Would this https://canada.newark.com/stewart-connector/ss-6488s-a-nf/connector-rj45-jack-8p8c-th/dp/56AC3197 work for you as a board mounted jack?

Chris -

I seem to remember something about using CO Dialtone. I looked, my Medco unit apparently bit the dust some time ago (who remembers when) and all I’ve got in are WECO or NE 6B units.

Let me know if you ever go into production.

Nice job!

Sam

I've made half a dozen so far. PM me and we'll see about getting them into service. I have the stuff to make 50 of them, so they're will be plenty.

That's exactly the type of jack I was looking for. I'll have to see if my board design program has the hole layout for that so I don't have to wing it.

Sam, if you still have the dead Melco, let me know. I can rebuild it unless its charcoal.

Thanks Chris, I'm sure it's long gone.

Sam

I just noticed that because I am in Canada my search brought up a Canadian source which I put in the line above. I just checked Digi-Key in the US and they have the same Stewart Connectors on their web site.

That page you linked had a link to the US version of their site. It's tough to design a board around parts you don't have, and it's hard to order parts if you don't know whether the program has their profile pre-included. I still have 30 or so of version 1 to solder up and get ready anyway.

Let me pose some questions to anyone who would be interested in these things.

What would be your choice for making terminations to one of these? A pigtail, an 8p8c jack, screw terminals (most expensive option), or other suggestions?

Would anyone be interested in a model that had four loop detectors in one package? The parts are simple and cheap enough, getting the board designed is simple enough, problem again is what would be a preference for connections?
For the four way model I was kind of thinking 6p2c jacks for the incoming and outgoing lines and then I'd only need 6 connections for battery and A leads.

I'm open to thoughts.

I haven't heard from RedBul for a while. He might be interested...unless he all ready has miniaturized 'em.

All this talk about A lead control wiped away some cobwebs in the old brain. In the 1987 AT&T Premises Distribution Products Catalog, two A lead adapters were listed. The Z153CM adapter provided A lead control for a single line phone where there had formerly been a key telephone set. Like the regular 153 adapters, it consisted of a female amphenol with a modular jack for a single line phone, but there was a small circuit board in the hood. I recall that these were sold hanging up in blister packages in the AT&T Telephone Stores in the late 80’s and early 90’s.
The 354A adapter was similar except listed to provide A lead control for a two line phone or two single line phones used in conjunction with a 267C adapter.
Have not been able to find any additional information on these adapters on EBay or the internet other than the AT&T practice number for the Z153CM (461-099-006PS).

I would want to see a Phoenix connector, popular these days. Surely you have that layout. But your choice of connectors depends on where that thing is going to be installed so maybe RJ jacks in and out with Phoenix for power? Also, you have a lot of unused real estate on that board, you could probably cut the board size down to 1/4 what you have there. If you are going to do one with multiple controls you're going to have to shrink the layout down anyway otherwise you'll have a board the size of Kansas.

-Hal

Hal, I kind of just went with the layout of the original Melco for that. I figured it was a good place to start. If I really put my brain to it, I could probably fit four on a board not much bigger than the one I have now. I’m trying to stay away from surface mount components because I don’t really have the means to solder them efficiently. Heck, if I went SMD, I could fit 6 on a board the size of the original. Through hole soldering is much more friendly for the home gamer. I was thinking I could fit four on a board about 4x6” pretty easily.

Absolutely agree about SMD. Maybe if it was around 30 years ago when I had better dexterity and could see without a magnifier I might think differently. But for what you are doing that's fine. I don't know what the Melco looked like, I never saw one. The ones I used were housed in something like a 1x2x3" plastic box. RJ-11 on one end for the SL device line cord and a line cord on the other with a RJ-14 plug on it for the T,R and A lead control. There may have been a cord to a wall wart but I' thinking it was line powered.


I did quite a few fax machines but they actually had A lead control on pins 2&5. Matter of fact I'll bet that you can find fax machines today that still have it. The times I needed A lead control was usually for answering machines. Single line phones I would modify for A lead.

-Hal

The problem with the line powered devices is they won't retrieve a call off hold. Most of the loop current is going through the hold bridge in the line card and there just isn't enough to work a relay coil. It's fine for getting a lamp so no one grabs the line or stopping the ringing when a call is answered, but they just will not cancel the hold. The melco devices, and by extension, my devices, will. They (in theory) will work on as little of 1 ma of loop current. It's actually looking for the 1.2 volt drop across a pair of diodes in series. That 1.2 volts lights the led in the opto and that fires the two transistors that pull the A lead to ground. It's devilishly simple. And for us nutcase collectors, really darned handy. If I answer a call on my 1A2 set on my kitchen counter, and then need to run into my workshop, I can grab the call on the partner phone out there no problem. When I was using a line powered loop current relay, I couldn't do that. It wouldn't fire when a call was on hold and I'd just hear hold music instead of the caller. Someone was asking me about creating a setup similar to mine with a 1A2 in conjunction with a Merlin system in his case. I figured it should be pretty easy to replicate the Melco, since the sandman relay I had just wasn't cutting it. That's what started this whole misadventure.

Now I'm going to have to look and see if my fax even has pins 2 and 5, let alone be wired for a leads....

Melco's

Wow pretty cool project.

Hello All!

My name is Ron, I live in Hilo, HI (the Big Island - where the volcano erupted a few months ago!) and I am running a 551C - with a mix of 8 phones - 3 lines and intercom.

Ten plus years ago - this forum - Ed and Arthur in particular - gave me the advise, wisdom, equipment and encouragement to set this all up here - and it has worked flawlessly in all of those 10 plus years!

I currently am running 3 MELCO S64-1's on each of the 3 lines - for FAX - Satellite TV - hand held etc.

I now need to add a 4th line - and of course I can find red hot lava 20 miles from my front door much easier than another MELCO S64-1!

I do however have a brand new Viking LDB-2 on hand (Ed must have sent me this - I sure don't remember it!) but while I understand the T&R in and out and all - what leads (and how) do I wire to the LDB-2 for contact points 5 & 6??

Any advice is greatly appreciated! (And Chris - I'd consider buying 4 of your new boards if you are so inclined?!?!? - Please advise as well!)

Mahalo and Aloha!

Ron

You need to connect A and A1 from the associated line. Pretty simple.

Mine are exact clones of the Melco's so if you can hook up one of those, you can easily hook up one of mine. Plus they work better than the line powered stuff anyway.

Shoot me a PM, I'm not building 50 of them for just myself!

Please note: Mine do not have a casing or anything. It is just the bare PCB and a short length of cat5 cable to terminate it. There's plenty of empty space on the board to drill some holes to mount it. I mounted mine with some standoffs and some drywall screws. It's not the prettiest looking thing, but it works better than the Sandman relay I had, so I don't much care.

Chris,
Honestly, what kind of money would it take to get a solid state version of 1A2?
It really isn't all that complicated. The interrupter could be likely be replaced with a microcontroller.

Thoughts? Because honestly, I'd comfortably pay $100 to $250 for a small form factor solid state 1A2 system just to have it to play around with.

Oh, and a suggestion that might be helpful to you for revision 2:

Consider adding an 8P8C/RJ-45 jack to your PCB so it is modular.

That's exactly what I'm planning to do.

Greg Ercolano is making a solid state 1A2, but he is intentionally using discrete logic instead of microcontrollers so anyone could build it. Micro's are awesome, but only if you have the means to burn them. He could just sell the boards and a parts list and anyone could assemble one. Heck, I'd buy one if it was like a DIY kit that had the bare pcb and a bag of parts. I love soldering stuff up like that.

I was just gonna say, I'll be damned... http://seriss.com/people/erco/1a2-multiline-board/

I'm losing my mind with how much I want one of these.

Scott's going Old School with the 1A2 gear.

I'm holding out for the four line version.

Seriously, if he makes a four line version, that big ugly 501 is coming off my backboard.

I have been busy working in my fourth (or is it my fifth?) career, so I'm late to the party.

If you all would consider the ComKey 416 system, you will see that you are re inventing the wheel, or the KSU. The ComKey system uses electronics to replicate 1A2 electromechanical components. The "5th line" module can be used as an example, to drive one line on a key set. I have done this for demonstration purposes.

It's fun watching Arthur. [Good to have you back Arthur]

Here is the wheel BSP 518-450-106

Uncle Arthur! Great to see you.