[Coco] MPIs & Cartridges With Solder/Tin Contacts Can Now Be fixed With A Gold Contact Plug Upgrade!

[Gene Heskett]

On Monday 16 September 2013 01:20:40 Kip Koon did opine:

> Hi Guys!
> 
> After a long search on the internet, I have finally found a very
> interesting male connector with Gold contacts on the male plug side
> that fits the Coco's Slot receptacle nicely and has stiff curly gold
> wires on the back of the connector.  The top wires are spaced 0.62"
> from the bottom wires which is perfect for soldering to the solder/tin
> contacts of all those MPIs' and cartridges' card edge contacts that
> don't work correctly anymore!  I have acquired a collection of items
> myself as I'm sure all of you have that desperately need fixing.  I'm
> going to try one on an original Radio Shack floppy controller I have
> with very poor contact ability due to the oxidization problem we are so
> familiar with and see how much better it performs.  I am also going to
> try one on a Gray MPI I upgraded to be compatible with the Coco 3 to
> see how that goes as well.  The Coco 3 will not boot up at all in the
> MPI's current state.  I have to check with the manufacturer, but I
> believe I can order these connectors with most any number of even
> numbered contacts, so I may be able to get a 4 contact or 6 contact
> version of the connector that would make it possible to extend the
> ground contacts that fit into the grounding receptacle as well as the
> 40 card edge contacts for the Coco Slot receptacle.
> 
> There is definitely light at the end of the tunnel for all these old
> MPIs and Cartridges that many of us can't get working reliably anymore!
>  I ordered 5 samples with the idea that there may be several hundred
> people that might want these connectors.  The company obviously sounds
> interested since they did send me the 5 samples!  I have no price yet
> as I have just the samples, but I figure that if I order them for
> everybody from the factory myself, then we may be able to get a
> quantity discount.  I will post a picture in my dropbox as soon as I
> can get a good picture taken and post a follow up email to all you guys
> as soon as possible.  No color photo is available, so I will be taking
> a picture myself of one of the connectors for you to see what they look
> like.  My hands shake a little and all I have is a cell phone, so I
> will do the best I can.  Stay tuned for this exciting development for
> our beloved Cocos!  The Saga Continues! Take care my friends!
> 
> Kip

Along those same lines, I found the side slot connector in most of my 
coco's was gold plated, which usually speaks well for dependability.

My next perp in the perp walk was the totally crappy, so called solder 
plated, edge pattern sticking out of the MPI.  This is the same ISA spacing 
pattern used in the old xt pattern pc's cards, so I grabbed an old, gold 
plated PC card and sawed off about 1/4" of its nose.  It even had finger to 
finger shorts in that 1/4".

I sawed 3 old cards off before I was able to find one that didn't have any 
internal shorts.

Then I ran the sawed edge of that piece over a sheet of 600 wet-r-dry 
sandpaper until the back edge where I had sawed was dead straight & smooth, 
best I could do since I didn't have the milling machine then.

Then the non-reversible step of sawing about .200" off the end of the MPI 
boards edge pattern, and carefully filing that until the two pieces fit, 
needing only a tiny drop of a highly silver bearing solder to bridge the 
gaps in the edge pattern.  That was close to 20 years ago.  I have never 
had to go back and touch up the solder dots, and it has, except for a 
timing glitch at the bus turnaround time that some additional jumpers from 
ground plane to ground plane, and a couple more .1 uf bypass caps have 
largely fixed a nearly 2 volt ground bounce, and it has Just Worked(TM) 
since.

There was a time when I considered offering that service to the group, but 
at 3 weeks short of 79, my hands aren't that steady anymore.  Not to 
mention that if I actually paid myself, the price for the fix would have 
stopped 99% of you.  But that, and the jumpering of all 4 slots pin 8's 
together, and removing 3 of the 4 pullup resistors attached to the 
individual pin 8, and the coco3 logic kit plus the remote power supply is 
the sum total of the mods I've made to one of the original but cream, not 
grey, MPI's.  And it still Just Works today.

Cheers, Gene
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My web page: <http://gene.homelinux.net:6309/gene> should be up!

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