K2 [DISPLAY] Button

[Ron McCurdy]

I'm building a K2.  The [DISPLAY] button shows a voltage of less than 2
volts and it is erratic and, the current is shown as 0.00.  I have checked
the voltages at U3 and they are 2.633 at pin 5, 6, & 7, and 13.75 at pins 2
& 3.  Pin 1 is .571.  I measured the voltage at Vsense on the MCU pin 5 and
it was 2.669.  Where could I be losing the signal to the lcd??

 

Ron, KE5QDA

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[Don Wilhelm-4]

Ron,

Do you have the Control Board P7 jumpered between pins 2 and 3 (marked INT)?
If so, what is the voltage at P7 pin 3?  How about pin 2? - both should
be about 0.3 volts below your supply voltage.  What is your supply
voltage when the K2 is powered on?  (Measure at the anode of RF Board
D10).  What is the voltage at the cathode of D13?
What is the voltage at each end of R9 - one end should be the same as
the cathode of D13 and the other end should be very close to 20% of the
voltage at the cathode of D13.  Control Board U3 pins 5, 6, and 7 should
also have the same voltage.
If any of these measurements are incorrect, look for the soldering
problem - connection not adequately soldered or a solder bridge.  Also
check to be certain R9 and R10 are the correct values.

73,
Don W3FPR

Ron McCurdy wrote:
> I'm building a K2.  The [DISPLAY] button shows a voltage of less than 2
> volts and it is erratic and, the current is shown as 0.00.  I have checked
> the voltages at U3 and they are 2.633 at pin 5, 6, & 7, and 13.75 at pins 2
> & 3.  Pin 1 is .571.  I measured the voltage at Vsense on the MCU pin 5 and
> it was 2.669.  Where could I be losing the signal to the lcd??
>
>  
>
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[Don Wilhelm-4]

Ron,

Upon re-reading your post, the voltage you measured at U3 pin 7 is about
what would be expected with a 13.5 volt power source.
Did you measure the U6 pin 5 voltage on the lead of the chip or at the
socket.  If you measured at the socket, try at the chip lead because you
may have a pin bent under the firmware chip or a bad socket connection.  
If you measure 2.633 (or 2.699) voltas on the actual microprocessor pin,
I believe you may have a bad input on that microprocessor - all the
display calculations are done in the firmware.

73,
Don W3FPR

Ron McCurdy wrote:

> I'm building a K2.  The [DISPLAY] button shows a voltage of less than 2
> volts and it is erratic and, the current is shown as 0.00.  I have checked
> the voltages at U3 and they are 2.633 at pin 5, 6, & 7, and 13.75 at pins 2
> & 3.  Pin 1 is .571.  I measured the voltage at Vsense on the MCU pin 5 and
> it was 2.669.  Where could I be losing the signal to the lcd??
>
>  
>
> Ron, KE5QDA
>
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