[Coco] MPI problem or ...???
gene.heskett at verizon.net
Thu Jun 21 23:41:30 EDT 2007
On Thursday 21 June 2007, Brian Blake wrote:
>Yes I do.
>Not having a service manual for this paricular unit I am currently thinking
> one of the IC's is bad, just had not gotten the scope out to look at any of
> the outputs. Just don't know where to start looking at this moment...
>Again, I haven't actually got the scope out to look, but, the DMM isn't
> picking up anything greater than .001vac. I'm not thinking that's enough to
> cause these problems, but, again, I've only recently got back to CoCoing...
>Thanks guys, keep the good info coming!!!!
>Brian (<- not an expert ;) )
A couple more things to check Brian since these things are nearly old enough
1. clean up all the blackened coating on the card edge connector that plugs
into the coco. Get brutal, as in a small piece of 0000 steel wool and some
contact cleaner & make it shine on both top and bottoom, and that includes
those 'ears' on each side as they are the main ground connection between the
coco and the mpi. Just don't power it up till all the steel wool has been
removed. That black stuff is just as good an insulator as that same black on
a battery post of your car battery. I got so tired of that that I sawed it
off, found a pc card with a gold plated finger pattern, and transplanted it.
That very tedious job was 15 years ago, and haven't had any problems with
2. If that mpi has not had the usual jumpering of all the card socket pin 8's
together, there is a probable problem there because the slot selection switch
has become oxidized and needs to be given a shot of cleaner and exercised.
Lots of exercise, then a couple more shots of contact cleaner.
Gene, a C.E.T.
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Sometimes, too long is too long.
- Joe Crowe
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