atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems Can anyone tell me why...

Matt -

You can't mix lamp leads and A/A1 on the same terminal. They used to make little holders for the spade leads (when you ran out of terminals), but you could always give them a little twist of wire and then some tape.

The ground off hook was designed for dial access to PA systems (as I recall). You went off hook on the ICM, dialed a number that pulled in a relay that would connect ICM T&R to a WMT1 matching xfrmr that would connect to the input of an amplifier. (we used to switch ground through the ICM and leave one side of the buzzers leaning on battery). The off hook ground held the relay up while you paged. When you hung up, the ground went away, the relay dropped off and was available for the next page.

Sam

And Finally.......

A Lead controls go for $20 and up... I think I can buld this one for less than $5. Gonna give it a shot anyway, seems to be exactly what I need and it's something to do on a rainy Sat.



Image courtesy of Bill Bowden, @

https://ourworld.compuserve.com/homepages/Bill_Bowden/

Thanks Sam, saw your post after my last. I'm gonna go ahead and build this guy, should have some news later this PM. Seems like a clean, inexpesive solution.

Matt, Put a 200V Full wave Bridge rectifier in the phone line leads before the 3.3 meg resistors on the phone line leads. Then when SWB reverses polarity, it will still work, and you don't have to check polarity when you hook up the circuit! It is possible that the additional resistance the FWB introduces will require that you reduce the 3.3 Meg resistors to 3.0 Meg. John C.

Beware the non-telephone company versions of A-lead control devices. Most are simple series relays, and geared toward phones with tone dialing. They are seldom engineered adequately to prevent relay chattering (and therefore lamp flickering) during pulse dialing.

You could also replace each of your 400-type line cards with a Melco M-487 if you can find them. They allow a single-line set to be wired to the output T & R and the KTU detects when the set goes off-hook. I'm sure Geraldo...er...Ed...has a few in his vault. I have two, but I'm hoarding them for my museum display. They originally cost over 200 bucks, as I recall, and could only be special-ordered by the boss.

I prefer using the A-lead conversion, though, because you can install an eentsy N/C pushbutton on the front of the 554 housing in series with the A-lead, and by pushing the button as you hang up, you can put the line on Hold, allowing you to take the call on one of the 2565's.

Wow, I do have the Teltone version of that card. I never even thought of that! Thanks, Arthur!

Well,

It WAS working just great, but I couldn't leave well enough alone. Went to tidy up some wires, and well, let's just say MOSFET's don't like it when you reverse the power leads. Made a nice flash though. Up to rat shack tomorrow for a new MOSFET.

Also the cost was a bit inflated as the only way to get a 3.3 Meg resisitor was to buy a bag of 300 misc values, of which I only needed 3. That alone would have been $17. So I opted to "make" a 3.3 Meg, which is why instead of 4 resistors you see 19.. lol - (3 1 Meg + 3 100K) * 3. Plus the one 10K resistor.

Total cost if they had all the parts I needed would have been around $10. I'll probably end up buying a commercial control, but it was a fun project, and it was pretty cool while it lasted.

It's still raining, so now my hobby for the day is now switching from soldering irons to aluminum cans, if ya know what I mean.

Arthur -

One thing, actually I kind of like it, but just wondering if it's "normal". Now that my SLT's are after the card, if an incoming call arrives, and I pick it up on a keyset, then pick up a SLT, then put the keyset back on hook... the line button flashes hold. Once I hang up the SLT, the keyset lamp goes out. Again, I like it, but wondering if maybe I did something wrong.

Thx
Matt

You need your SLT's to have their T/R connected AHEAD of the line card, not behind it.

Otherwise, there MUST be a slight delay between when the A leads open/close as opposed to the T/R switch hook leads. It looks like your circuit design causes the T/R and A lead closures to occur at the same time, which will never work with your SLT's T/R connected on the station side of the line card.

Ed -

That's the way I originaly had it, but if it's setup that way, and a call is picked up on a 2565, then someone else picks up a SLT... they get LOTS of noise until I hang up the 2565. After much checking, double checking, checking your comments (all the leads you listed from the 2565's dead end at the 66 block, with no cross connects, jumpers or clips hooked to them), as well as checking Bills suggestions.... I decided to try putting the SLT's after the card.... noise went away completely, as well as did a scratching sound that has been present on the 2565's.

So I'm a little confused on my next move, mainly because I still don't understand why the noise is present when wired as you describe.....

I'm sure I'll get it figured out eventually.

With a lot of help.