[TenTec] Corsair - blank LED segments

[Dr. Gerald N. Johnson]

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 at 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 at gmail.com>
>>> To: Discussion of Ten-Tec Equipment<tentec at 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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