sundance-communications.com/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems Manual needed for 551KSU

John thanks,alway nice to hear what worked. Ed I tell ya some day I'll find those BSP's and then I can compete with ya.

Ok new issue when ring voltage is applied to a CO side Tip and Ring I am getting relay chatter on the L relay. The 400D never starts the interupter it just gives a slight hum. I have checked pins 15 and 17 and they have 24 volts I have checked the ring gen its giving 120 vac. Any ideas?

Oh also this KSU I purchased from another person so it does have some straping changes.

Thanks

Try testing it with nothing connected on the station side tip/ring. You are sending your CO tip and ring to the tip/ring input on the lower left side of the block aren't you?

You definitely should not be hearing chatter, it should be a very faint buzz from the reed relay and then one of the standard relays will click. After that, all you should hear is the interrupter motor running.

Have you confirmed that your power supply is providing 24 volts DC and not AC? Chattering relays sounds like maybe they are getting AC. It's also possible that your interrupter motor voltage selection strap might be connected to both the 10 volts AC and the 24 volts DC. This would backfeed AC into the DC control power.

Rocks dont live as long as 1A2 does. That system could go through a flood, dry out and still work.

Sorry for the delay I did some voltage readings and there is not any AC on the A or B batt supply. The cards respond to the A link being closed but when the card is idle and ring voltage is put on he CO side it just humms and never does anything else.

Any ideas?

I will try to run down the Qwest techs Monday to see if they'll let me borrow the 1A2 manuels. When you say no voltage on the AorB supply you talking the 66 blocks or on the power supply its self?

OK, so you are positive that your A and B battery is clean. Make sure that you have 10 volts AC on the MB/MG and LB/LG terminals (lower-right side of the 66 block). If you don't have it in both places, then they need to be strapped together, MB to LB and MG to LG. I think you had mentioned that some factory strapping was missing and that's is definitely factory strapping.

Then, let's try something else. Connect a jumper from any ground on the power supply to the ST terminal on the block for just a second or two (lower right also). If your interrupter wiring is good, it will start running (you will hear the motor). It will stop on its own after about five seconds. If you hear the same humming you mentioned earlier, then there's a good chance the interrupter is frozen and that's the humming your'e hearing. That's not a problem at all to replace and I have some of them available.

I guess we will need to know when you say "it just hums", do you know what is actually humming? Is it a component on the line card or the interrupter motor?

Let us know your progress.

Hey Ed..This is just old memory here, but didn't weird things happen if an external ground wasn't placed on it? What I mean is a ground to the power supply ground, not just a 3 prong plug.

Bill: There were some wierd things that happened if the Lamp, A and B battery, and ringing grounds weren't common.

Now, with 400D and earlier line cards, yes, a VERY good ground was mandatory or they wouldn't detect incoming ringing.

Wow! You may have just solved this guy's problem! If the KSU doesn't have a good ground (on the proper terminal, not just the third prong on the line cord), the line card's reed relay will just sit there and buzz but not start the ring cycle operation.

John-WW1: Do you have a good earth ground connected to the terminal at the bottom of the KSU below the 66 block? If you don't and you are just bench-testing, then that could be your problem. Also, on the same note, make sure that tip and ring polarity are correct on the CO line.

Thanks, Bill. That one slipped my mind completely (as with most things these days).

Hope it really helped. Maybe I just get lucky once in awhile.