Intellivision reset switch

[Jules Richardson]

On 04/02/2017 08:51 PM, drlegendre . wrote:
> If the unit was otherwise working as-found, then it might be safe to say
> that whatever +was+ under that button +must+ have either disintegrated or
> fallen out of place, yet evidence should remain. In either case, you should
> find evidence - crumbled, gunky old foam, or shrapnel of a busted plastic /
> rubber spring. Point being, if it hasn't been opened up (to repair) in the
> past, everything should still be inside, at least in some form.

Well, it seems that there isn't supposed to be anything! The metal plate is 
dished and is supposed to deform when the reset switch is pressed, making 
contact with the PCB, and then returning to original shape when the case 
switch is released. Except that - which is the case with mine - it seems 
that they have a habit of deforming slightly over time (and also coming 
loose, potentially shorting out various components and causing damage).

Bending the tabs which are supposed to hold it against the PCB at least 
made it secure, but it still wouldn't return to original shape after being 
pressed. So, I figured I could hunt around for a replacement plate from a 
donor console, and *maybe* it would be OK, and *maybe* it would last for a 
few years. But in the end it seemed better to implement a more robust 
solution: it just so happened that a standard miniature microswitch (the 
type with four pins, dpst) would fit nicely onto the PCB, with the pins - 
after a little bending - sliding through the PCB slots which used to retain 
the original metal plate. A couple of short jump wires to nearby PCB pads 
later, and electrically it was perfect.

The downside to this is that I had to shorten the stem on the plastic case 
part of the reset switch by ~ 1/8" to compensate for the increased height 
of the microswitch, and I really don't like "destructive" mods. However, I 
figure the rework will easily last the life of the console, and at least 
there's no risk of things coming apart and damaging the logic now. I 
suppose Mattel would have spent the extra few cents on a real switch anyway 
if the design life of the console had been more than a few years :)

cheers

Jules