Re: Looking for a spare 8502

From: Marko Mäkelä (
Date: 2004-11-19 14:27:35

On Wed, Nov 17, 2004 at 08:40:10PM -0500, William Levak wrote:
> Did you measure the voltage on the CASS SENSE line?  A logic probe would
> be ideal.  It is normally at +5V, and is pulled low when the play switch
> is depressed. 

It was about 1.1 volts.  After I disconnected pin 26 of the processor
from the CASS SENSE line, it was much higher (I don't remember how much,
but I think it was well over 3 volts.)

> If your 8502 is socketed you can test it by pulling it up and bending out
> pin 26.  If the problem persists, the 8502 is definitely bad.

The disconnected pin 26 was at -.462 volts.  I first misread it as -4.62
and wondered if I had flipped the polarity.  So, it looks like the 8502
is broken. :-(


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