[Elecraft] K2 S-meter/LED display flickers, alignment fails

[Don Wilhelm]

Doug,

The most common cause for behavior of that nature is bad solder 
connections.  I suggest you reflow the soldering on the front panel 
board with an iron temperature between 700 and 750 deg F.
Especially check (or reflow) the soldering at Front Panel RP2, the LED 
bargraph, R12 and U4.

Using the menu for CAL S HI, you should be able to turn the RF Gain 
control so that each LED is illuminated in turn (use the BAR mode).  
This will allow you to see when all the bars are functional

After you have the bargraph working correctly, try the S-meter 
calibration again.

73,
Don W3FPR
Douglas Furton wrote:
> Hello.  I'm building K2 #6761 and have reached the first operational checkpoint.  My K2 started right up and works normally except for S-meter/LED display problem I describe here.
>
> When working through the first S-meter alignment, I find that the LED display behaves erratically.  First, it only operates when I'm in the menu -- the none of the LED elements light when I exit the menu.  Second, when I go through the process to set the meter's low and high points, several elements -- and not adjacent elements -- light and flicker.  While I seem to be able to set the low point for the S-meter, I cannot set the high point because of the way the display flickers.  I can't get just a single element (9 or 10) to light.
>
> I have the meter set to 'dot' mode, but do note that the LED display seems to behave close to normal in 'bar' mode, although I still can't align it properly and it doesn't work once I exit the menu.
>
> I'll note also that my 8V regulator seems to be on the low end of specs, but I can get 3.80 Volts on pin 5 of U2.
>
> Any suggestions?
>
> Doug
> K8EXB
>   
>