Corsair or Corsair II? Your post says Corsair. There is not much in
common between Corsair and Corsair II displays. My post is based on the
original Corsair schematics where ALL the digits come from the counter.
On the II, the segment driver for the MHz digits is different from the
segment driver for the KHZ and Hz digits. And so the connections between
the boards is different. Its not likely to be a display LED problem
though a shorted LED could conceivable blow the driver which is
protected a little by a series resistor. I expect a bad cable connection
rather than a bad IC or resistor.
73, Jerry, K0CQ
On 4/6/2011 4:29 PM, Barry N1EU wrote:
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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