[Elecraft] [K2] voltage/current sensing K2 SN 4277

[Don Wilhelm]

Karl,

The voltages at U3B (pins 5, 6, and 7) are correct.  Check to see if the 
voltage at U6 pin 5 is the same as at U3 pin 7 - it should be.
In this case, the fact that the display indicates a low voltage says 
either that the trace between U3 pin 1 and U6 pin 5 is broken, or that 
the U6 pin 5 input is faulty.

As for the display of current part, either Q11 is misbehaving or there 
is something wrong with R7 (check for solder bridges).
That may be correct if part of the receiver is not functioning.  The 
normal current draw is 0.240 to 0.270 amps dependent on the options 
installed.

You did not say what your "poking around inside" consisted of.  If you 
induced static charge on some of the pins of U6 that could be the cause 
- OTOH, if you were soldering, look for solder in places where it should 
not be (solder bridge).

73,
Don W3FPR

On 3/26/2015 5:25 PM, Karl Erb wrote:
> Display now reads E00.7 i0.06 and low batt following my poking around inside.  Following guidance in the archives I measured (RX mode — TX display readings of swr, pwr seem ok)
>
> D10 anode 13.89,  cathode 13.69 volts
> Pins 2 and 3 of xxx 13.65 and 13.65
> R9 voltages 13.67 and 2.62
> R8 voltages  13.65 and 13.65
> U3 voltages (1) 13.57 transitioning to 0 after 1 sec; (2) 13.65; (3) 13.61 transitioning to 0;  (4) 0; (5) 2.61; (6)2.66; (7)2.66; (8) 13.61
> U6 pin 5    2.66V
>
>