Questions about 74154 and 6821 on System 11

AE35

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Hi guys!

I would really like to know these two small things about System 11B

The 74154 at U44 does pin 18 and 19 connect to the same trace? If no, then
there's a fault on my board connecting these two legs.

The PIA 6821/6820 at U41, there's two legs that should connect on the board.
I am correct in assuming that they should be leg 37 and 38?

Thank you very much!!

Nicholas
 
My Taxi manual shows:

U44 pins 18 and 19 BOTH going to ground.

U41 pins 37 and 38 are both connected to the IRQ "not" line.

Chris
 
You still beating up on that System 11 board? Hey, whatever I can do to help, I am working on THREE of them right now and they are - fun......;>).

Chris
 
Yes I am:)

Oh, one more question....the 555 timer in the blanking section, does leg #2
go to nothing underneath the board, or does it go to the trace that go
to the middle transistor leg?

Yeah, I gave up on the EM I was restoring, and then went to this. *sigh*
 
No, man, EM's are more fun. Well, for you maybe - not for me....(lol)

U43, the 555, pin 2 goes to four components:

1) Base, middle leg of Q50, a 2N4403
2) One side of R80 (3.3k)
3) One side of R81 (6.8k)
4) One side of C57 (.047uF cap)

Get out that ohmmeter!

Chris
 
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