Re: Apple //c Sporadically Crashing into the Monitor

[mjmahon@aol.com (Michael J. Mahon)]

Stephen Adams replied:

> "Michael J. Mahon" <mjmahon@aol.com> wrote in message
>> 20040414152114.17367.00000399@mb-m16.aol.com">news:20040414152114.17367.00000399@mb-m16.aol.com...
>> : Bill Garber wrote:
>> :
>> : >It could be that the RAM expansion cards pins has
>> : >deformed the sockets in which the CPU and MMU have
>> : >to return to. What you can do is replace the sockets
>> : >one at a time in the motherboard, if you have the skills,
>> : >and see if this remedies the situation.
>> :
>> : I agree that deformation of the sockets is the most likely
>> cause.
>> :
>> : If you'd like to avoid the tricky desoldering job, though, you can
>> : simply "piggyback" your CPU and IOU chips on two 40-pin
>> : machined pin sockets, which will plug securely into the
>> : main board sockets.
>> :
>> : You must use _machined pin_ sockets for this to work.
>> : They cost a little more (a buck or two) but this is a much
>> : safer repair than desoldering unless you have special tools
>> : and some experience.
>
>The suggestions about the deformation of the motherboard's sockets makes 
>sense. I remember that when I reinstalled the CPU and MMU, they just 
>sort of slid in a bit too easily.
>
>I went back and removed those two chips for a closer examination. The 
>first thing I noticed was the amount of tarnish on all the legs. I used 
>the old ink eraser trick to remove the crud. Then, I carefully bent the 
>legs out slightly all the way down both chips (straightening out a 
>couple on the end that weren't exactly straight). When I reinserted both 
>after these actions, they both "clicked" in, taking only slightly more 
>pressure to seat. After closely looking around and not seeing any bent 
>or broken pins, I closed up the case.

While tinned pins are a bit more tolerant of abrasion than
gold-plated fingers, it is always best to use the least abrasive
cleaning method.  The reason for this is that the plating forms
an air-tight seal, protecting the underlying metal from corrosion
and consequent high contact resistance.  Abrasives can leave
microscopic furrows in which the protective plating is removed.

You will find that an ordinary rubber _pencil_ eraser is perfectly
suited to cleaning both tinned and gold-plated metal.  Just one
or two strokes (usually "away" to minimize eraser dust) is plenty
to remove the very thin surface film.

>The Apple //c has now been running for seven hours straight with no 
>crashing!  :)

Congratulations--very nice job!

<snip>

>Thanks to all who offered assistance. It was appreciated.

You're very welcome--and your own approach was even simpler. ;-)

-michael

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