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Meat Plow[_5_] Meat Plow[_5_] is offline
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Default OT--Actual elecytronics repair question

On Tue, 11 Jan 2011 14:28:38 -0800, Dave Platt wrote:

In article , Gareth Magennis
wrote:

Yaesu VX-5R tri-band hand held. Momentary contact power on/off button.

I've owned this radio for 9 or 10 years. Recently I have to push
several times on this rubber on/off button to get the radio to come
on. But it always takes just one touch to turn it off. And the radio
works fine otherwise including all the other buttons. Just have to
play around pressing the button maybe three/four/five times. Sometimes
it powers on when pressed once! But always shuts off with just one
easy push. This indicates to me that it's not a problem with button
contact but rather a microprocessor problem.


Could be a microprocessor controlled delay programme whereby you have to
hold the on button on for longer to turn it on, than the off button to
turn it off. Perhaps because it is more important to screen out
accidental ons than accidental offs.

And/Or, If the button is dirty, and thus resets its state
randomly/rapidly during a single press, perhaps this results in favour
of the Off debounce and/or delay routines rather than the "On" routines.


Quite reasonable suggestions.

The usual "field engineering" fix would be to simply replace the
elastomeric key membrane (Yaesu used to make this available as a
standard service item for the VX-5; dunno if it's still available) or
use the CAIG contact-repair kit to re-goop the back of the POWER button
and see if increasing its conductivity fixes the problem.


I had the unit apart way back when it was new to install the MARS
coverage modification which was just a snip of a wire. The keypad was
that of silicone rubber and a carbon dot on the working side. Pretty
standard. Plus another membrane for water protection. The unit isn't
rated as being water resistant but obviously a handy talkie should have
some moisture resistance. I wouldn't rule out Gareth's observation. It
probably is easier to kill the process than to start it. Only one thing
bothers me and that is I have the add on barometric pressure sensing unit
and it displays when the VX-5 is off. So the microprocessor runs while
the unit is off unless the pressure unit has its own processing.



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