missing segment in display

[daleputnam]

Howdy Don,
   A display, that shows all the segments one time or another, depending on the state or mode, i.e. in cw normal, the bottow segment of the "c" is missing.. but it shows in "u",  has me confused. The soldering has been rechecked, under a 30x glass, on the front panel and control board, and the display has been scrutinized.
Any guidance or thoughts?
  How does the display "know" the difference of which mode the radio is in... it would only "know" what the driver tells it?
 
thank you,

--... ...-- Dale - WC7S in Wy

     
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[Don Wilhelm-4]

  Dale,

The K2 microprocessor sends serial data to the display controller (IDAT
and ICLK signals), and the display controller lights the corresponding
segments on the LCD.

So a missing segment on the "c" mode indicator can be either a missing
bit in the data from the microprocessor ( CB U6) or it could be a bad
bit in the display controller character generator.

To check the character generator, go into the menu and look at any other
displayed lower case "c" (Secondary menu "rTc" or "Acc" for instance.  
If the lower segment is missing on all occurrences of a lower case c,
then the display controller (FP U1) has the problem, but if it only
occurs in the mode display, the microprocessor is to blame.  If you have
access to another K2, temporary replacement is the best way to determine
which one is the culprit.

73,
Don W3FPR

On 10/8/2010 8:10 AM, Dale Putnam wrote:

> Howdy Don,
>     A display, that shows all the segments one time or another, depending on the state or mode, i.e. in cw normal, the bottow segment of the "c" is missing.. but it shows in "u",  has me confused. The soldering has been rechecked, under a 30x glass, on the front panel and control board, and the display has been scrutinized.
> Any guidance or thoughts?
>    How does the display "know" the difference of which mode the radio is in... it would only "know" what the driver tells it?
>
> thank you,
>
> --... ...-- Dale - WC7S in Wy
>
>    
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

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