Elecraft K2 Owner's Manual - Manual (Page 156)

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053 +8V too low
(< 7.5V)  Inspect the entire 8V path on the RF and
control boards. Look for heat-damaged
components or solder bridges.
 Unsolder the output pin of the 8V regulator
and bend it up slightly to break contact with
the PC board. If the voltage is still too low
measured at the pin, replace the regulator.
 There are a number of places where you can
easily break the 8V line to eliminate parts of
the circuit in your search for the problem.
One example is RFC16 on the RF board. If
you lift one end of this inductor it will
disconnect the entire synthesizer from the 8V
line.
 A number of circuits have resistors in series
with the 8V line, for example R112 in series
with the I.F. amplifier (U12). If you measure
voltage on both sides of these resistors you
may find a circuit that is drawing high
current or is shorted. Example: If you
measured 7V on one side of R112 and 3V on
the other, it would indicate that U12 had a
current drain of 180 mA, which is much too
high (I = E/R = 4/22 = 0.18).
060 No display on
LCD  If the bar-graph is also not working, check
the 5V regulator (052)
 Remove the front panel hardware and panel
from the front panel PC board and inspect the
entire board for shorts or incorrect
components. You may have LCD driver U1
in backwards or it may have a bent pin.
 Check the values of R15 and R16 on the
bottom of the board; these resistors set the
voltage for the LCD itself.
 Re-install the front panel board and turn on
the K2. Using a voltmeter, measure the
voltages on pins 16 and 17 of front panel
connector J1 (ICLK and IDAT). These lines
should show DC voltages between 0 and 5V
due to data transmission from the
microprocessor to the LCD driver. If the
voltages are fixed at either 0 V or 5V rather
than being somewhere in-between, the MCU
may not be functioning (075)
065 Relay Problem  If you suspect a ground short in any relay-
controlled circuit (LPF, BPF, VCO) you can
simplify debugging by pulling out the control
board, then turning power ON and back OFF.
This places all relays in the RESET condition
(see schematic).
 If you hear no relays on power-up, check the
IOC (080)