Re: Looking for a spare 8502

From: Marko Mäkelä (
Date: 2004-11-18 15:01:09

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. 

I didn't.  That's what I will be testing next.

> 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.  If it is
> not socketed, you will have to cut the trace.  You can solder it back
> later.

The chip is not socketed, but I have successfully desoldered a single pin
from a solder-through chip earlier.  It's not that hard.  I heat the pin
from the side, and then use the tip of the soldering iron or a small
screwdriver as a "crowbar" to pull the pin from its hole.  I haven't tried
this technique for desoldering entire chips, though; there, a desoldering
pump is likely to work better.


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