Elecraft K2 Owner's Manual - Manual (Page 153)

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Appendix E, Troubleshooting
If you have any difficulty with your K2:
 Closely examine all PC boards for poor solder joints and incorrect,
broken or missing components.
 Look for your problem in the Troubleshooting Tables (below).
 Follow the step-by-step receiver and transmitter Signal-Tracing
procedures at the end of this section. Also included are complete DC
Voltage Tables for all ICs and transistors.
Troubleshooting Tables
There are five troubleshooting tables (listed below). Within each table,
problems are identified by 3-digit numbers in the ranges shown. In most cases
you’ll know which table to look in based on the symptoms you observe. If in
doubt, start with the General Troubleshooting table.
General Troubleshooting
000-049
Control Circuits 050-099
Receiver 100-149
Transmitter 150-199
Operation and Alignment 200-249
When referring to components on the various K2 boards in the table, we will
sometimes use a shorthand form such as “RF-U11,” which means U11 on the
RF board.
INFO Messages
If you see a message such as
I N F O 10 0 on the LCD, look up the
corresponding entry in the troubleshooting tables. Note: INF O messages
can be cleared by pressing any switch. However, the cause of these messages
should be investigated before continuing to operate the transceiver.
General Troubleshooting (000-049)
Problem Troubleshooting Steps
000 Unit appears to be
completely dead when
power switch is turned
on (no display, no
audio)  Make sure your power supply or battery is
connected, turned on, and isn’t plugged in
backwards
 Check power supply and battery fuses if
applicable
 The K2’s internal self-resetting fuse, F1, may
have gone into a high-resistance state due to
a short from the 12-V line to ground; unplug
the power supply and check for such shorts
 Examine power cable for shorts or opens
 Verify control board is plugged in and that its
connectors are fully seated
 Check for 12 VDC at the power jack
 Make sure speaker, battery, and other internal
option connectors are not swapped or
plugged in backwards
 Measure the +5V and +8V regulated power
supplies. If either is incorrect, check the
regulators (050).
 Check the MCU (075)
003 LCD is dim  Check values of R16 and R15 on the front
panel
 Check continuity from LCD driver (U1) to
LCD. Also look for bent pins on driver.
004 Display turns on
but unit still appears
functionally dead or is
“running slowly”  Check the MCU, Control-U6 (075)
 Verify that the control and front panel boards
are plugged in correctly
 The MCU oscillator may be shorted out due
to solder flux residue, especially if you used
water-soluble flux solder (030)
005 No display, but
audio is OK  Remove the bottom cover and verify that the
front panel connector is properly mated with
the RF board
 If the front panel is plugged in correctly but
the problem still persists, check all LCD
voltages and control lines (060)