atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems 501A KSU Line 5 issues

I Finally got my ITT 501A KSU up and running with W.E. 400H CKTs. Everything works fine except Line 5. I get no light nor signal, except when I select the line key and ring it I get a audible ringing signal. I've tried several different line cards.

You need to go back and re-write your remarks in a way that we can trouble-shoot logically.

"I get no light nor signal" means...what? What kind of "signal"? Did you mean "I get no light or DIAL TONE" ?

"Audible ringing signal" Is there any other kind?

Are you using a common audible wiring arrangement?

How many telephones do you have connected?

Do you hear dial tone at the 5T and 5R terminals in the KSU?

If you pop the cover of a phone, do you hear dial tone at the 5T and 5R terminals on the key?

"except when I select the line key and ring it I get a audible ringing signal."

How do you mean "select the line key and ring it"?

Now, as to lamps, can you ground the A lead for line 5 at the KSU and hear the relay in the line card operating? Does a test lamp connected right at the 5LG and 5L terminals light when you do this?

sorry about that I don't know where I left my mind lately... I have only one phone so far. I'm using the common audible arrangement. when I press line 5 I get no dial tone or light. When I ring the line from my merlin pbx, The test light and the interrupter does not activate. if I press the line key and pick up the receiver i can hear a ringing signal.

hope that helps.

Sounds like an open A lead.

As Arthur suggested, open the KSU and short the Black/Brown pair - the light should come on. If it doesn't, remove the station wiring and try again. If it still doesn't, then the internal KSU cabling is open or has been removed.

Very often line 5 was used for an Intercom. 401 B Intercom and Dial Intercoms did not need an A lead. Perhaps it was "stolen" for some other use.

If the lamp does light, then try shorting the line from inside the set.

As far as hearing ringing signal, but not dial tone, you might be "off half a pair on the cut down". Double check your wiring.

Sam

I was able to short the line from inside the KSU but not on the set. I have also checked the wiring to the phone and everything seems to be fine.

I also forgot the telephone set I have is a NOS ITT 564

Shorting things is not a reliable method of testing telephone circuits. You need to use a test set.

Plug a single-ended 25-pair cable with a male Amphenol plug into the cable that serves the telephone in question. Then test the 13th pair (Bk/Gr) with a test set. If you do not hear dial tone, (and assuming that you really ***did*** punch down the Bk/Gr correctly at the KSU) then you have an open pair in the cable. The chances against this are about 1,000,000,000 to one. The chances that you did not punch the pair down correctly are about 1 in 25.

I figured it out. On block C, The 66 Block teeth were not grabbing the cable. Thanks for all the help.

on line 5 tip/ring

Glad it worked out.

Sam