Thanks for the info Jerry. It's printed and filed with my Corsair II manuals.
Dave
WA3MKB
-------------- Original message --------------
From: Jerry Volpe <kg6tt@arrl.net>
> Display problem encountered and fixed.
>
> Two weeks ago during the CQ WW DX contest I suddenly lost my display on
> the Corsair II. The internal keyer also ceased functioning as well (the
> keyer and display are controlled by the same processor). Turning the
> Corsair off and then on again resulted in a blank display (except for
> the decimal point). In all other ways the Corsair II worked correctly.
> Turning the Corsair II off for 20 minutes or more brought the display
> back to life... for a while. I did notice that it took up to 10 seconds
> or more from the time the Corsair II was turned on till the display
> initialized itself. Before its initial malfunction the display always
> initialized with a second or less.
>
> Ad investigation of the display circuit pointed to three suspects... U10
> the display processor, the 4.05 MHz crystal, and C6 a small electrolytic
> capacitor that provides a reset pulse on power on. As the frequency
> display was stable and accurate until the freeze I didn't think the
> crystal was an issue. The processor was still a suspect but it made
> sense to check the capacitor first. I removed C6 (connected to pin 28 of
> U10) and upon testing it I obtained very erratic capacitive readings. I
> replaced C6 with a known good 2.2uf/50 vdc electrolytic.
>
> The Corsair II's display now initializes correctly and shows the
> operating frequency in about one half a second from power on. Since this
> repair there have been no further display lock up incidents.
>
> Perhaps this may be of value to other Corsair II owners. If your display
> is initializing more than a few seconds after power on this capacitor is
> probably changing values and that is a good precursor to the problem I
> just experienced.
>
> 73,
>
> Jerry, KG6TT
> Fairfield, CA
>
> --
> Ralph Jerald "Jerry" Volpe
> Amateur Radio Operator KG6TT
> ARRL Member & VE
> FISTS 12304
>
> 788 Chestnut Drive
> Fairfield, CA 94533
>
> kg6tt@arrl.net
>
> 510 325-7724
> 707 399-8838 FAX
>
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