possible obtronix PCB error

3 replies [Last post]
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Joined: Jun 5 2008
Posts: 381

Hi folks,

From the posted high res pictures, it appears that the 74154 is not properly grounded. This is the 24 pin DIP at the center of the board. Pin 12 should go to ground according to the data sheet. Can someone with a actually board check this out?

Regards,
Mike Willegal

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Offline
Joined: Apr 13 2006
Posts: 39
75154 Ground

Mike,

I was able to see the trace to ground on a bare board using a magnifying glass. It's short, but it's there.

John Calande

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John Calande
http://apple1computer.blogspot.com/

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Joined: Apr 13 2006
Posts: 39
PCB Error DOES exist on NON-kit distributed board

Hey guys,

I was wrong, I was looking at the KIT board and pin-12 of the 74164 is grounded.

HOWEVER, on the second board that I have, which was NOT sold as part of the kit, pin 12 is not grounded. There is also another bug on this board which M.Willegal found recently, and that is on D-7 74166, pins 7 and 10 should be connected and they are not.

John Calande
http://apple1computer.blogspot.com/

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John Calande
http://apple1computer.blogspot.com/

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Joined: Apr 13 2006
Posts: 39
74161 not the 74166

Pins 7 and 10 should be connected on D-7 74161
not the 74166 as I incorrectly mentioned.
Sorry for the confusion.

John

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John Calande
http://apple1computer.blogspot.com/