atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems A question that makes you go "hum"

Cool - I've got a great place to start using it. I just punched down my cuckoo clock, and for some reason line 4 is lit brightly on all phones, except the clock, which is very dimly lit. The LED on the line card is lit... for some reason it thinks it's off hook. I pulled the line card for now. So I guess a short between A/A1 somewhere on line 4..... but I think it will be an excellent way for you to help walk me through both using the meter and also avoiding the guessing and parts swapping game.

Thanks
Matt

Matt, knee-jerk reaction to your newest problem. You've x-connected like its a 5 button phone, on a 10 button phone block! John C. (Not Garand)

Matt -

The line steadily lit is, as you guessed, probably a short on line 4s A/A1 pair. Troubleshoot this by lifting A leads one at a time till the lamp goes out. That set is causing your problem. Then find out why. Swap that set out with a known good set to see if it's a cable problem or a set problem.

If the lamps are bright on most phones and dim on one set, that set probably has the L & LG leads reversed. Check to see if it's a xconnect, cable or station problem.

Sam

Sam/Lightning -

It's even worse than that.

The first thing I did was try another station, with the same results, so I knew the cuckoo clock was OK.

When I put the system in, I punched down about 7 or 8 stations, but only used 5 of them.

As luck would have it, for the cuckoo clock I picked the one station cable that had been cross connected... umm... wrong.

I'm a bit embarresed to go into the details, but what the h... suffice to say I had my A/A1 and L/LG cross connects reversed.

Basically A/A1 from the KSU were going to the stations L/LG, and KSU L/LG were going to the stations A/A1. Why that didn't cause smoke... I don't know.

Basically I got 2 pairs of cross connects wrong... Ed drilled it into my head: Wh/Blu, Blu/wh, W/Or, Or/Wh, Wh/Gr, Gr/Wh for the xconnects. But on this particular drop I had revered the Orange pair with the Green pair on the cross connects. Didn't take long to find it.

I don't understand how hooking A/A1 from the deskset to L/LG of the KSU wouldn't at least blow a fuse, since it seems to me that's a 10v dead short when you pick up the reciever.... maybe you guys can offer up some possibilities.

Anyway, I made the cross connects for line 4 the same as every other set... it's all good now. And I inspected every other cross connect. All good.

Thanks guys!

:bang:

- Matt

Arthur -

I want it for the looks/coolness factor, but is it just an ohmmeter? With 45V in it, I've got to think it does something a normal VOM does not.

I've got a digital VOM.... use it all the time with the 1A2 and many other things around the house/car. Again, very cool item, but if it's an ohmmeter I need, I like the one I've got... nice big LCD display (my eyes ain't what they once were), plus it's got swappable probes/clips on the leads.

But, I went ahead and threw a bid in. It's old, I'm old, my phone system is old... we all get along just great.

Thanks
Matt

"I don't understand how hooking A/A1 from the deskset to L/LG of the KSU wouldn't at least blow a fuse, since it seems to me that's a 10v dead short when you pick up the reciever.... maybe you guys can offer up some possibilities."
Matt, because it's a 1A2! Among other things, the 22/24 gauge wire helps limit current flow. 1A2's are damnear bullet proof! If you want a phone system that will ALWAYS work, make it a 1A2. No bells or whistles, but they will survive just about anything but a lightning strike on the chassis!

And you'll find that an analog VOM comes in handy when you are trying to see those 'kicks'. A digital meter, that samples continuosly, will probably never see the 'kick' and if it does, it'll only show it to you for a second or so.

Digital meters have their uses. One is put it on AC, measure across a DC source, and get the ripple voltage. Analog usually gives a 'kick' and then nothing. John C. (Not Garand)

Reversing the A/A1 and LG/L would only cause the lamp to try to short the A/A1 leads, but the resistance would likely not be enough to close the relay and energize the LG/L. If it did, then YES, going off-hook on that line would blow the fuse since your phone's A-lead contacts would place a dead short across the line's lamp circuit.

Oh and the reason for the funky 45 volt battery in the KS meter is to simulate the voltage of a standard CO line for testing and "kicking" the cable pair. A standard meter might work fine for on-premise wiring issues where cable runs are relatively short, but when working on CO line issues where pairs may be miles-long, you need the added horsepower to provide accurate measurements.

Cool, cool - thanks lightning! And I agree with your assesment - this thing IS bullet proof. Or in lieu of a gun, I'd use one of these desksets as a defense mechanism any day of the week.

Thanks for the tips on the analog meter - we'll see if I win the bid. I havn't used an analog meter since I was 8 or 9, should be fun.

Thanks again -
Matt

Wow, all of us in one thread at the same time - thanks for the additional tips, Ed! With your guys responses, now I know why not even a whiff of magic smoke came out.

Thanks again -
Matt