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

Looking good Joe - You're further alone with the backboard etc. than I've gotten pth loose equipment, but I do have one question that I didn't see in a quick scan of this thread:

Are you using a "real" phone line, and is the KSU properly grounded? I've found problems trying to use simulators and or extension ports from phone systems to supply dial tone - partly due to the reason that some versions of the 400 KTU were looking for ring voltage between tip and ground (or was it ring and ground) instead of tip-to-ring as supplied by most current equipment.

You all missed a clue:

No flash on incoming.

He hasn't grounded the KSU.

jknichols has a valid thought! The first 1A2 system I ever put in, I assumed (there's that word again) the AC outlet ground would be adequate. WRONG! I had to run an EARTH ground! Wouldn't recognize incoming ring until I did, then everything worked.

If all the wiring checks out OK,there is the possibility that the line cards have been damaged. 1A2 equipment became available in the mid-sixties, but it took nearly a decade for Bell Labs to recognise what was causing a maddeningly intermittant line card failure. BSP 518-010-108 issue 4 states that when local frequency generators[110 volts,30hertz] are used for common audible signalling with ringers, large transients can be generated with high enough voltage to damage line cards and blow fuses. The fix they came up with was the 141a protector, which was just a 68k resistor in a small plastic case that plugged across the 66 clips for each pair of b1 and r1 terminals. The 141a protectors were required at all new installations and on existing installations when visited for a service call.{Only for 400d line cards-400g&h line cards have internal protection.]

Hey, Joe TTY:

Take a piece of cross-connection wire, and fasten one end to the ground block in the KSU and the other end to the screw in the outlet. Then try an incoming call. Tell us if the interrupter starts.

Hi all,

I am at work now, but I will try the ground tonight and report back. I will also try the 10V lamp thing between the LG and LB pins on the block.

Thanks again for the help!

Joe

One other thing... I do have 400D KTU cards. However, I do hear the relay 'clunk' when I depress the line button. I do not know if they are damaged or not. Also, once the line one button is depressed, I get a dial tone and am able to use the line (sans ringing). I am anxious to get home to try grounding the unit.


Best,

Joe

Western Electric 400D KTU's need a local ground for the ring-up circuit to operate properly.

It's not a protection ground wire, so don't go crazy with a large gauge wire. Just a piece of X-conn or quad wire with all four leads twisted together is sufficient. Quad makes a nicer-looking solution.

Other WE later issues, and San/Bar 4000F cards, for example, do not require the ground.

If your dial tone comes from a non-ILEC ATA,and you use 400D's, you'll be SOL. You'll need the SB 4000F's.

My phone service is a simple POTS line. There is no DSL or call waiting or even caller ID. (Right now, I get internet access through CATV. At the new diggs, we will have Hughes net until either CATV or DSL gets out that far.)

I have checked the polarity of the POTS line, and it is correct.

I will indeed try grounding the system tonight and seeing what happens!

Best,

Joe