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Re: [TenTec] Corsair II problem

To: tentec@contesting.com
Subject: Re: [TenTec] Corsair II problem
From: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Reply-to: geraldj@weather.net, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Thu, 20 Jan 2011 20:59:12 -0600
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
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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