[R-390] R-390A power switch

[Charles Steinmetz]

Barry wrote:

>I think that may be a fairly common "fix" for the switch.  I know 
>just exercising the plunger for a little while started it working 
>again.  I assume it's just stuck down due to stray lube and/or dust 
>causing the plunger to stay depressed.

There are any number of reasons that the microswitch may be stuck 
"on."  One is that contact arcing welded the contacts together.  That 
is all too common on these radios and is the problem that Jim's 
snubber is designed to reduce or eliminate.

Welded contacts may come unstuck from "exercise," particularly if you 
pull the microswitch off the switch assembly and put the actuator 
through a greater range of motion than it normally sees.  However, 
once a switch arcs, it always arcs more easily afterwards.  Sometimes 
dressing the contacts can help, but once you have the radio that far 
apart it makes sense to just put in a new microswitch.

Best regards,

Charles