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Old 10-18-2007, 01:12 PM
Geoff Harrison Geoff Harrison is offline
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Join Date: Feb 2007
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Quote:
Originally Posted by Architect View Post
I finished the kit and it seems to work. However, the CLEAR button doesn't clear the data LEDs. The INPUT LED lights up though. Some other key combinations result in most of the LEDs to go out, so it is not the K-register. Any data key pressed leads to all data LEDs to light up.
That's similar to the problem had at first, especially having all the data lights light up for any data key pressed.

It sounds like the K register is shifting when it shouldn't. Try checking the ICs and signals driving pin 6 on IC 104 & 105 (i.e. ICs 107, 116, 120, 121). Make sure pin 6 is not stuck low. In my case I had a bad 7420 @120.
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