Thanks Jerry, Clayton and Steve!
What was throwing me for a loop is that the Corsair II manual really
messes up this section - the text is copied from the Corsair I manual
but the counter logic circuitry is completely different. To their
credit, the correct updated schematics are included in the Corsair II
manual. The Corsair II uses 81246 Logic Board -> 81247 Display Driver
-> 81248 Display Board while the text still references 80973 Logic
Board, etc.
As Steve suggests, it IS an odd fault because the megahertz digit also
shows the same fault so we can't easily isolate it to the driver of
the khz/hz digits. I'm going to try and hang a scope probe on the
segment line and see if it is dead back to the display driver chips.
If so, I guess it could be a bad 68705 or ???
Thanks & 73,
Barry N1EU
On Wed, Apr 6, 2011 at 9:17 PM, Dr. Gerald N. Johnson
<geraldj@weather.net> wrote:
> I just checked the Corsair manual. Definitely multiplexed and on two
> boards so it could be the connection of that segment between the boards,
> the driver chip, or the counter chip. Page 3-27 in the manual I
> downloaded from TenTec some time ago.
>
> 73, Jerry, K0CQ
>
> On 4/6/2011 4:11 PM, Clayton Brantley wrote:
>> Barry: I have never dug into displays but most of them are multiplexed and
>> the
>> drive for that segment
>> in all the digits is most likely at fault. Look at the display drawing and
>> it
>> should show what is driving
>> that particular segment.
>>
>> I'll look at a drawing a bit later and see if there is anything obivious.
>> Right
>> now, I'm going but the seat
>> of my pants. Hi
>>
>> Good luck.
>> Clayton N4EV
>>
>>
>>
>>
>> ________________________________
>> From: Barry N1EU<barry.n1eu@gmail.com>
>> To: Discussion of Ten-Tec Equipment<tentec@contesting.com>
>> Sent: Wed, April 6, 2011 4:00:00 PM
>> Subject: [TenTec] Corsair - blank LED segments
>>
>> I've never mucked around with the LED freq display before but the
>> lower left vertical segment is out on ALL four digits of a Corsair LED
>> frequency display. In other words, "6" looks like "5" and "8" looks
>> like "9". Do they share something in common that would point to the
>> source of the trouble? Obvious things to check?
>>
>> Thanks& 73,
>> Barry N1EU
>> _______________________________________________
>>
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