Telephone Switching > Electro-Mehanical Key Systems (1A1, 1A2 etc)

Oldest 400-type 1A2 linecard?

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Otto Vaughan:
So I now realize this one actually does say "400B" in solder on the underside  Right above "R 7/76" (refurbished) in the last photo.  It was so over soldered it didn't loo like lettering initially.   So I am still wondering what is underneath the 400B sticker.  Seems odd they would but "400B" on top of "400B"!


Perhaps a different version? Or the addition of the diode changed it to a B.

I've seen metal frame cards before but it's been a very long time.

Does it need a system ground to Ring up during an incoming cycle, or will it ring up in either case.

I remember the D cards prior to version 15 required a system ground to Ring up.

And the option block is on the card end, not the head as they were later.
Did they have a C card as well, and E.
I can't find anything on this old of a card, in my BSPs.

I've heard of E cards but I guess they are very rare to find. But I've not heard of C s so I don't know if there was such.
But that's a very cool piece of key system history you have.


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