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Oldest 400-type 1A2 linecard?

Started by Otto Vaughan, September 08, 2021, 02:45:00 PM

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Otto Vaughan

I recently came across a Western Electric 1A2 line card with component dates of  IV-63.  1963 is very early for 1A2 equipment.
It has a sticker on top of a sticker  that IDs it as a 400B line card but I suspect under the top sticker the original sticker says  400A.

I know the difference between the 400A and 400B is the addition of a diode.  I will investigate to see if that diode was added.

Does anyone have a 400A card?  Or something earlier than "IV-63"?

Any interest in a photograph?  The option block appears unique too.

Rick Walsh


I've never seen a 400A or B. That's definitely old.
Does it work?


"C'est pas une restauration, c'est une rénovation."--François Martin.

Otto Vaughan

Yes the card works

Believe it started life as a 400A and was upgraded to 400B (diode added).  I have a 1965 400B that has "400B" in the traces on the underside; the 1963 card does not.
Here are pics

Otto Vaughan

more pics

Note early option block with wire wickets (and copper sleeves)


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.