[TenTec] Corsair II problem

[Dr. Gerald N. Johnson]

That capacitor on the reset pin may not be terribly critical, I'd expect 
anything from 1 mf to 10 mf would work adequately because electrolytics 
have very loose tolerances anyway.

An open capacitor on the +5 volts will keep the processor from executing 
correctly also.

73, Jerry, K0CQ

On 1/20/2011 8:52 PM, Don Rasmussen wrote:
> Thanks Dr. Jerry,
>
> I swapped the 68C05 into another radio and it works fine. There is 5V on the pins where it is required, and I can hear the crystal oscillating using an external receiver. All this, plus the fact that it worked intermittently for a couple cycles before it finally stopped working seems to indicate that the capacitor on the RESET pin may not be allowing the processor to do a reset at power up. I'll try to find something near 2.2 mf to test with and order the proper part if that works. Thanks for the info. Don.
>
> =====================================================
>
> The counter, display driver, and keyer are all done by a 68C05 on the
> display board. It fails when the electrolytics go bad. It can also fail
> from loosing power from a dirty board connection. It doesn't control any
> of the radio, so everything else will work without the display, just you
> don't know easily here you are tuned. History says replacing the
> electrolytic or two on that board usually fixes it. Order up the lowest
> ESR, highest temperature rated one from Mouser or Digi-Key to get the
> longest life.
>
> 73, Jerry, K0CQ
>
>
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