I have looked at the pinout, it is different, but you can use a method called "dead-bug"
to wire the 7442 in place of the n8251.

I've attached the spec sheet for the n8251 to this email.

Karl

----- Original Message ----- From: "Karl-Wilhelm Wacker" <kwwac...@ptd.net> To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk@classiccmp.org>
Sent: Sunday, July 24, 2016 1:13 PM
Subject: Re: Signetics N8251 source?


Mattis:

 By the description, it is a 1 of 10 decoder chip.

 Have you looked to see if it pinout compatable
with a 7442?

Karl

----- Original Message ----- From: "Mattis Lind" <mattisl...@gmail.com> To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk@classiccmp.org>
Sent: Sunday, July 24, 2016 5:01 AM
Subject: Signetics N8251 source?


After successfully repairing the G231 module of the MM11-L set I continued
with the next one. This one was not able to access addresses ending 0100
(binary). Luckily it was not the transistors arrays that were bad but the
selector chip. A Signetics N8251 chip.

I found a source on ebay at $4.95 each plus $13 shipping. A little bit to
much for my taste (although I could make an offer)

Anyone know of a cheaper source? I could use five or ten maybe.

/Mattis

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