atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems Operation of Com Key 416 primary w/out 91A connect block?

I have a Com Key 416 primary set with an unknown operational history, and would like to verify its standard features. Thing is, I *don't* have a 91A connection block.

I assume (possibly incorrectly) the primary can be operated without the 91A by just giving it AC, and putting T/R on pins 1+26.

I've done this, and green lights work when I pickup the line, speaker and DSS/ICM modes work, and I can dial and make calls.

But.. Hold and Ringing don't work:

1) Putting a line on hold just seems to drop the call, and the green light simply goes out, it doesn't wink or give an indication the call's on hold. When I go back to the line, call is definitely dropped.

2) When I try to call the line from a cell phone, it doesn't ring, and green light doesn't flash, but if I pickup the line, I can take the call.

Regarding #2, I've verified:

* 4 switches under the DSS faceplate all in the ON position (to enable ring),

* Volume is set to '5' (SPKR and ICM work, and I can DSS the set and hear myself talk)

* Verified the LINE 1&2 vs LINE 3&4 connector on the logic board is in the correct LINE 1&2 position

I've tried using other lines, with same results.

An odd symptom: when I call the set from the cell, not only doesn't it ring, but after about two rings, the CO drops the call with an busy "error" signal; on the cell's earpiece I hear the CO give a few audible rings, followed by a double-busy signal, then disconnect.

I take this odd behavior it to mean the set is doing "something bad" to the line when a ring voltage comes in, causing the CO to drop the call after a few rings.

If I pick up the line during the first few CO generated rings I hear in the calling receiver, I can take the call normally. And after I hang up, I can re-seize the line to get dialtone, and make a new call.. so it's hanging up properly, and not keeping the line held.

I've tried swapping T/R, but that's not it, because then I get dialtone but can't dial. So I've ruled that out.

I'm guessing maybe the absence of the 91A is causing this? Or should Hold + Ring work without it? (seems everything else does)

If I need a 91A, are there any schematics for it such that maybe I can rig it to work? I'm an EE guy, so depending on what the 91A does, I might be able to fake it. (From the pic in the manual, it seems possibly simple enough.) Otherwise I guess I might have to track one down.

Thanks for any help/advice.

In coming CO lines for line one goes on 24 and 49 the violet brown pair, not the white blue pair. With just a primary I don't think you'd need the 91A, but I don't have that manual. CO's went on v/br and v/sl pairs of the primary sets.

EDIT: After thinking about this a bit the 91A only gave you access to the v/br and v/sl anyway. I remember putting the CO's on at punch blocks and not using the 91A or B.

The set isn't doing anything "bad", it is just wired incorrectly as Bill mentioned. Violet/brown for line #1 and Violet/slate for line #2.

Greg, while not likely, you may have damaged it by connecting the CO line on the protected side of the set's circuitry and exposing it to ringing voltage. Only proper connections will tell.

Bill, you are correct with your assumption regarding the 91 block. All it really did is to isolate the violet/green through violet/slate pairs so that the CO lines could be fed in at the wall outlet if desired.

Ahh, the little legend at the *bottom* of the table in the com key manual.. missed that.. where it says T1 on 49 and R1 on 24 for line 1/3.

Yes, I'll try rewiring for that, and will cross fingers that the ring voltage didn't nuke anything in the phone. I'll bet the parts are durable enough ..will follow up when I try that after dinner.

The overall design of the ComKey 416 system, with others, was to protect the general public from the dangers of central office line voltages. I can't say for sure, but I believe that the intent of the 416 was to eventually be a user-installable system.

True, the hardware is very rugged and resilient to improper wiring. My fingers are crossed that no harm was done. From what you have described, the extent of your testing/troubleshooting was limited enough to where no harm may have been done. Had it been left connected like this for dozens of calls, then there may be room for concern. Something tells me that if a 1983 vintage phone lasted this long, you should be fine.

Please check back and let us know how you make out.

Yep, works great now when hooked up correctly.

Wow, I haven't heard that ring in years.

Thanks much for the fast help.

Nothing blown.

I've noodled with Com Key satellite sets over the years as a curiosity, and based on the hybrid and touchtone circuits in them, they really appear to be POTS designs with all the usual precautions for CO line voltages.

Although I'm sure there's front end circuitry to prevent ring voltages from reaching the Com Key voice paths, still when a call is in progress, the voice path circuits are exposed to raw CO line voltages, so it would have to be somewhat impervious to brief wacky voltage swings from the CO during line transitions; ie. pickups during ringing, rats chewing at lines, lines crossed, lightning, etc.

For instance, when I've got the phone wired correctly to the CO on 49+24, I can see the CO's 48VDC on 1+26 even when the line is idle, and when I pick up, it jumps down to 6 or 7 in the usual way.

Where I think you could blow up Com Key is if you were to put CO voltages on the logic paths, or cross it with the 24 VDC supply voltages on 45 and 20. Definitely the logic board's circuitry appears to all be low voltage stuff; that little 7805 regulator tells me it's good ol' TTL 5VDC voltage levels.

Thanks again!

Oh, and I have a little Com Key web page over here:
https://seriss.com/people/erco/comkey416/

..which I'll probably flesh out over the next few weeks, now that I actually have a primary set to study. I included today's info in there as well. Comments welcome.

Glad to hear it worked out! Thanks for getting back to us and letting us know.

Sam

From your warning note:

Actually T1/R1 is the output of the key system lines. The incoming CO lines went on T/R.


By the way to the board.

That's good information, Greg. I'm glad that everything worked out for you in your quest. There are a few things that you'll probably want to verify though:

1. The other phone model numbers in the 830/2830 series were for a different family of ComKey systems, namely the 718, 1434 and 2152. These systems were completely incompatible with the 416 system or phones. They also used a KSU, and a mighty large one at that. The 416 system always used the 9XX/29XX series phones only.

2. An RJ21X is a bridged network interface, providing up to 25 two-wire POTS or similar lines on a punch-down connecting block. It is a common misnomer to refer to a 25 pair "Ampenol-type" connector as an RJ21X, but this is very much incorrect. The same thing applies to the improper use of the term "RJ45". People today believe "if it walks like a duck, quacks like a duck, then it must be a duck". There are literally thousands of wiring patterns that can be accommodated using a 25 pair connector, with USOC RJ21X being one of them.

3. You are correct when you state that the satellite sets don't contain much in the way of electronics with the exception of the amplifier. Mis-wiring CO lines into them on the white/blue obviously won't cause the satellite phones any harm, but back-feeding them into the protected interface circuitry in the primary sets could possibly cause harm to them.