atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems KSU issues

I was not able to edit my comments regarding the various ringing arrangements, due to this forum's timing rules, so please insert these comments in my above message at the appropriate point.

(2) (a) it is wired as part of a larger wiring scheme, called "common ringing" (the individual ringer is abbreviated CMB for "common bell." In this scheme, the ringing current comes from a local supply of generator, such as a wall-mounted power unit (20- or 30-type) or from a small "wall wart" type supply, the 118A, that mounts inside the KSU. The ringers are factory-wired in series with the network capacitor.

(2) (b) Similar to the above scheme (local generator supply) but the ringers are energized via a diode matrix, allowing the ringers in telephones of a large system to be arranged in groups that may or may not overlap. The network capacitor is bypassed in this scheme, since the ringers are operated with DC via the diodes in the matrix block.

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To wire a key telephone for line ringing, you can either punch down the ringer pair (slate/yellow) of the running cable directly onto the CO T&R terminals in the KSU or at an intermediate wiring block,

**OR**

You can open the telephone, and find the red/black ringer leads that are terminated on terminals RT and RR, (you will also see the slate/yellow pair terminated on those screws) and move them to the T&R of the CO line you want to ring on that telephone. Example 1T & 1R for line 1, 2T & 2R for line 2, etc. Doing it this way, you would wire one telephone for ringing on line 1, and another telephone for ringing in line 2.

Ok, here's the update and another minor puzzle: I bypassed the ring extender and DSL filter (I doubt the DSL filter had anything to do with it but I had to anyway) and lo and behold, all the lights work as does the interrupter on both lines. However, still no ringing on either line. The ringer in the phone does work. Arthur, I think on a previous post you told me a 2565 needed 15 pairs to work everything. This KSU has only 12 pair punched down and I wonder if that is the problem. I thought the ringing was via CMB but I don't see the frequency generator. I thought that was built in to the KSU. Also I should say I really don't care if the individual phone rings, as line 2 is actually a dedicated fax line and I was planning on using a separate external ringer that chimes. However, I hoped that with an intercom system, I could dial from one phone to another and it would ring or buzz.
Here is the puzzle: when trying to bypass the ring extender, I disconnected the box where the wires went to the house, plugged in a mod-spade line cord and connected that to the connectors on the KSU. When I picked up the phone, I started hearing a loud click every three seconds. Any ideas on that?
Finally, although you are a fount of knowledge, I must say you are wrong regarding the interrupter when you say "The screw is just to hold the cover on." There are two screws that hold the cover on, but a third screw just to the left of the one cover screw is accessible through a hole in the plastic cover. I still don't know wha this screw does but it definitely does not hold on the plastic cover.

Arthur, my KSU has the gray lift-off plastic cover with 66 block mounted off center to the right of the KTU slots.

"However, still no ringing on either line. The ringer in the phone does work." How did you test it?

A 2565 needs no set amount of pairs to work. You need to read the BSP, and try to understand that these systems use wired features, rather than software features. You use as many wires as you need to, to get the job done. The ringer is factory-wired to the slate/yellow pair. It needs to be punched down (at least) on the T&R of a line to make it ring.

The screw holds the interrupter into the KSU.

"A 2565 needs no set amount of pairs to work.." Hmmm...Would you make that statement if the words "fully and completely" were added? Obviously the slate/yellow pair needs to be punched down for the ringer to work from CO power.
Back to my plan: Can one of these KSUs be configured to ring each phone with a Melco or Tone Commander intercom? Do you need the frequency generator and supplemental power supply to do this? And ditto for regular incoming calls. Am I wrong to assume the only way to get this KSU to ring on incoming is to punch down slate/yellow and let the CO power it?

Dial selective intercoms require an entire new course of study. See below.

Before we go on to them, you really need to understand that I am not typing to hear myself type, and I do not want to engage in a debate about numbers of pairs, or any other aspect of 1A2.

You have been given suggestions about reading BSP's. You need to take those suggestions seriously. You have asked us questions and then after much conjecture and trying to decipher what you are asking, you hit us with information that would have been very helpful had you divulged it at the beginning (Example, the fact that you are using a ring extender, and that you don't have the tools handy to do the suggested wiring changes.)

It is not obvious (or even true) that the yellow/slate needs to be punched down for the ringer to be energized by a CO line. In fact, in one of my messages to you, I explained that the red and black ringer leads can be assigned to a T & R pair right in the phone.

Dial intercoms do not (generally) use ringers. They use low voltage buzzers. The dial intercom units, whether relay versions or packaged electronic ones, use A battery for talking, B battery for signal (relay) supply and (generally) 10Vac for buzzers.

The only thing that a dial intercom key appearance has in common with a CO line is the fact that a button is assigned to the circuit on each telephone, and that the buttons light up on all the phones so equipped.

Please do a Google search for "207C KTU" or "Teltone R10" "Teltone T10" "Teltone C19" or "Melco" or "Tone Commander" and read the practices for these units.

The typical dial intercom unit is not a part of the KSU. It is added to the KSU if the box can accommodate it physically or it is mounted on the backboard near the KSU. A 25-pair cable is terminated on a 66 block, and cross-connections are run to the 66 blocks that serve the telephone sets.

A dial intercom can use the power supply from a KSU, as explained in the practices. It will not fit in a shoebox. It uses a T&R pair, a LG/L pair, and a buzzer pair per telephone, per button. The T&R is bridged, creating a common talk path. Similarly, the LG/L pair is multipled to each station. The buzzer leads are dedicated to each particular telephone set.

Arthur, I am sorry if I offended you or any other members of this forum by seems to be being difficult to work with. I have never been a Bell or WE employee - I am a collector whose primary goal or dream was to have a working 1A2 system in my home. I hope you can understand my frustration that I have been working on collecting the parts I need for the 1A2 system for 5 years and had to pack everything up so the rest of the 25-pair cable could be run. Now I cannot find anything. I can't remember what I had for breakfast much less that I had a Viking ring booster installed. My current phone system was professionally installed so I don't know all the nuances of the system. I also believe you never answered me as to what kind of KSU I have put in service. I know it's not the 551B because it is marked. I know it is either a 551A or C. Once I identify it, I will look up the corresponding BSP.

Bill, you have a 551C KSU. The plastic lift-off cover is the dead giveaway. The 551A and B KSUs were all-metal construction with a door that opened to the right containing the power supply, card slots and interrupter.

Just to reiterate what Arthur has already said:

It doesn't sound as if your 551C KSU has a 118B frequency (ring voltage) generator installed. This was an optional item, similar to a large black "wall wart". It had a short black power cord with a male and female (pass-through) configuration. This allowed it to plug into the incoming power cord and then the internal 28B2 power supply would plug into the back side. This whole power cord setup tucked neatly into a channel in the KSU's base. Quite impressive design in my book.

Anyway, the 118B mounted onto a custom metal bracket to allow it to hang in front of the interrupter. As Arthur would say, these brackets were made of "unobtanium" even when they really did exist. We often saw these ring generators affixed to the interrupter with cable ties, Velcro, double-sided tape; whatever it took. More often than not, the ring generator was stuck to the wall somehow instead. For such a remarkable KSU design, I'll never understand why they made the ring generator part of things so bloody difficult.

Keep in mind that the 551 series of KSUs were never designed to support dial intercom setups. Yes, button/buzzer arrangements could be accommodated easily, but that is all that they were ever designed to do. Don't get me wrong; there's no reason that external dial intercom systems can't be used with a 551, and they can even be powered by the 551s power supply outputs (within reason). The issue is, as Arthur said, the addition of these intercoms is a completely separate operation.

With 400D line cards, there is a way to configure them to provide common ringing on all lines. ITT's 400E cards also allowed this. The key is that the lines have to be "real" central office lines, not fake dial tone from silly toys like cable EMTAs, Vonage boxes, etc. If the CO line has a ground reference, 1A2 can make a lot of things happen. We'll have to address this some other time.

It's best to get you fully-operational with the basic functions of the KSU and phones before we delve into the intercom options.

Oh, and also as Arthur said with regard to then number of pairs required for a 2565 to operate, here's a hint: Grounds are your friends. Common grounds are even better.

By referring to the BSP's you could have easily sorted out what KSU you have. The BSP's have photos and drawings. It's moot now, but the simple fact is that they all are electrically equivalent.

I think my 551B has the frequency generator as Ev described. Should have probably used that one instead of the 551C but the 551C had two cables already punched down and ready, and it was promised to be operational. All my other KSUs were purchased off of eBay "as is". Thank you all for your help and I will get to the intercom when I get everything else wired up.