sundance-communications.com/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems 400D KTU Issue 14/15 schematic needed

Hi Sam,
OK about the G & H cards I hope the ones I get can go the job for me. If they work out they should last as they're not exposed to any outside voltage stresses from lightning, etc. So, we'll see how they work - I don't want to reinvent the wheel. I will advise how it works out.
The Link that Jim & Arthur gave me was another good source of info to add to my collection. I have some paper documentation that is so old, the paper is starting to turn yellow. Lots of good info & people on this forum.

George

Hi George, that does sound like a nice setup. I have been trying to find an excuse to set up a 1A2 system at home (I only have one line and one phone in the house, so I don't really need a phone system!). I like your idea about interfacing the 1A2 with your ham radio equipment. That sounds like a good enough excuse, maybe I'll try that when I get a chance. I'm w8nwo, by the way!

I could connect each radio to a key and hook up a speakerphone so that I had an easy to select what radio I want to listen to. I also like your idea about using a key for PTT as well. It would function much like a tone remote. If I really got bored (highly unlikely as I work 40+ hrs a week and go to college), I could even wire this in to my home phone and set up a phone patch. If I ever get to this project, I might give you a call (or email or whatever)!

-Nelson

Neat stuff! Gotta ask, what is an 'OM'?

YM's become OM's. OM's marry YL's who then become XYL's.

It's really very simple.

-73-

click to learn a new language

I think I'll go grab another 807 :toast:

haha thanks for the lesson "Uncle Arthur"

OM = old man. A compliment in ham radio, it means someone (not necessarily old) who is experienced.

Just a quite follow up on my problem. Putting in the new 400G line card didn't solve the problem. I had to disable the on card ring detection circuit of the line relay by removing the series 6.8k (7.5k) resistor and then tieing in a 6N139 optoisolator to have it make (short) ot the line relay contact when detecting a ring to make it all to work.

I gotta go. More details later.

George

I think you violated the warranty!


Sam

Here's the lengthy follow up of the ringing/hangup problem using my magicjack with a Panasonic FAX/Answer machine and 1A2 system 400G line card. The problem was I would get a few cycles of ringing voltage that was detected and then the MJ would disconnect the caller. Here's a pix of the ringing waveform. Right click on it for full view.


As you can see, I would get a few cycles of the ring voltage, and then it would disconnect. I think the line card momentarily closes the line relay contact, then opens up and the call gets disconnected. This also happened with my original 400D line cards.
Anyway, the work around I came up with involves disconnecting the ring detector section of the 327A line relay (the 755 Ohm coil) and adding a 6N139 optoisolator (or equilavent) ring detector circuit to the line card. See the schematic.


The modification to the standard WE(mine is ISSue2) 400G card involves disconnecting (unsoldering & lifting) one end of R2, a 6.8k or 7.5k, (depending on the version, there's only one on the card). The end you want is the point closest to the edge of the card. This solder hole connects to C1, the 1.1 uF capacitor, which you will connect the optoisolator circuit to. This is shown as point "A" on the schematic. The 47k resistor will connect to that solder hole. The other end of C1 stays connected to the line card and eventually connects to Pin 14 (T-(CO)of the line card. The 2.2 MOhm resistor is soldered directly across the capacitor, C1, and is used to provide some small reverse bias to the optoisolator diode. The reverse bias is to help prevent false "dings" from voltage spikes. The 1N914 is for reverse voltage protection from the ~60 Volt ringing. Pin 3 of the 6N139 is connected to any convenient solder hole that goes to pin 9 (R+(CO)) of the line card to complete the ringing detector pickup circuit. The output polarity from my MJ worked out this way in order for my old TT pads to operate - yours may be different. In that case, just reverse the T&R from the MJ.

The output side of the 6N139 is a regular Darlington configuration (Pin 6 & 8 tied together) and connects across the N.O. contacts of the 327A line relay (there are no N.C. contacts). To get the polarity correct, pin 6 & 8(+) of the 6N139 goes to the solder contact closest to the blue handle of the line card. There is ~13 Volts across the output circuit. The 24 Volt zener is to protect the output from any voltage spikes from the other 24 Volt relay coils on the card, any ~24 Volt zener will work here. The line relay contact is still used for the normal line card hold functions, etc.

This circuit was constructed "dead bug style" around an 8 pin DIP IC socket and has been working for about a week now with no problems. I wanted to completely document this "fix" so others that experience the same problem don't have to reinvent the wheel. My 1A2 system continues to live! Any comments or additions - please send 'em on... (Is there a better way to post images?)

Sam - I can just solder back the one end of the 6.8k resistor and not void the warranty! - ha ha.

George