sundance-communications.com/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems ITT 400E's Broken or Not?

Thanks much everyone for the ideas. And Happy new year.

Repairmen liked the clicking relays. They allowed the repairman to locate the correct card in an electrical closet that might have 100 or so in service. You asked the secretary to slowly operate the switch hook, until the correct one was found, by listening and feeling for the vibration. This was before the cards were equipped with LED's.

I really like the ITT 400E cards. I've only had a couple fail. Both times it was bad diodes. Nothing special, just your garden variety 1N400x type. I keep a bucket of 1N4007's around so I just swapped them with those. They work just ducky.

They don't have that stupid thing of some western electric cards where they only ring up on grounded ringing (like pre issue 15 400D's) or some of the wackyness of the later WECO 400 cards. I had some 400H's that if you quickly pressed the hold button and released it (LIKE ANYONE NORMALLY WOULD) it would drop the call. You had to keep the hold button depressed for a solid second or more to reliably hold the call. They've since been sitting on a shelf for 5 years. I like the issue 15 400D's. 5 of my 6 line cards are currently those. They work wonderfully. Someone at the Lancaster TCI show a couple years ago had a 1A2 rack with like 5 or 6 loaded 584 panels and I asked if he'd sell some of the line cards. He said sure, so I picked out all the Iss 15 400D's. I doubt I paid him more than a few dollars a piece for them.

400D cards allowed for common audible ringing without a ring generator. Yep, that's what I said.

Chris, the cards that you refer to actually needed the line to be engaged for a second or two, before you could them on HOLD. It wasn't a case of the length of time you held the button down I discovered that "feature" on the job, after throwing away a few before I figured it out.

I always thought this issue with the 400H cards wasn't an issue at all. I thought it was intentional to discourage people from placing lines on hold and tying up equipment in the CO/PBX.

I would agree. I saw it as an additional feature, e.g. allowing to drop accidentally picked up line (from unrestored button) just by hitting the hold as a button restoration. Apparently there is no need to place a bare dial tone (with no incoming call or any dialed number) on hold. 400H effectively prevents such “false hold” situation.

400H has another advantage of being more “solid state”, having only a single mercury wetted contacts reed relay. So it is “silent” in operation with no audible clicks like from other relay-based line cards. This is only an advantage when the KSU is placed in the same room as phones, not in a separate closet. One can still hear the interruptor running, but only when hold or ringing occurs.

A big disadvantage of 400H is its zero repairability due to several custom ICs used for handling the logic. So if the card is troublesome it can only be thrown away rather than repaired.

THIS IS A SECRET YOU MUST NOT KEEP

I'm going to try this right now, and if you're lying to me.....

Who am I kidding, I'll just whine some more and then get over it.

He was right....

However, they don't work with my 451B MOH card, so back on the shelf it goes.