The SWTPC 6800 Repair Quest Continues

From: Barry Peterson <bmpete_at_swbell.net>
Date: Wed Mar 18 16:35:40 1998

On Wed, 18 Mar 1998 10:41:19 -0600 (CST), you said:

>
>Ok, so I swapped out the 7474 with a socket (checked) and a 74LS74 and I
>get the exact same behavior...all the input signals are the appropriate
>voltages but the outputs are still reversed.
>
>This means, of course, that either there are some 'sneaky fast pulses' on
>one of the input lines or that Q on the 7474, which is connected to pin 2
>(not halt) of the 6800 is grounded. I've checked and it's not physically
>grounded.

I don't remember the original post but; try pulling the chip and
bending the Q pin so it doesn't go in the socket. That should give you
a (floating) high.
_______________

Barry Peterson bmpete_at_swbell.net
Husband to Diane, Father to Doug,
Grandfather to Zoe and Tegan.
Received on Wed Mar 18 1998 - 16:35:40 GMT