ELECRAFT K 2 Owner's Manual page 124

K2 Manual 1/24/99 V.XC ©1999 Elecraft
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 0V or 5V rather
than being somewhere in-between, the MCU
may not be functioning (075)
§
075 Possible MCU Measure the voltage on pin 31 of the MCU
(U6, control board). If it is not 5V, check the
problem
5V regulator (052).
§
Remove the control board and carefully
inspect the microprocessor. Make sure it is
not installed backwards, has no bent pins,
and is seated firmly in its socket.
§
Verify that the MCU oscillator components
all have the correct values and are soldered
properly, with no shorts (X2, C21, C22).
§
080 Possible IOC If you saw the message INFO 080, the I/O
controller (IOC, RF/U1) did not respond to
Problem
messages from the main processor (MCU).
Turn power OFF and back ON; if you hear
some relays switching on power-up, the IOC
may be OK, and the problem is likely to be
with the AuxBus (081)
§
If you do not hear any relays switching on
power-up, your IOC (RF/U1) may be
defective. Inspect U1 carefully to see if you
have installed it backwards or if any pins are
bent.
§
Pull U1 out, check its pins, then re-install it,
making sure all pins make good contact with
the IC socket.
§
Remove the bottom cover and verify that all
pins of U1's socket are soldered, as well as
those of the 6V regulator (RF/U2), and U1's
4 MHz oscillator (RF/Z5).
§
With power ON, check all voltages
associated with U1. You should see 6V at
pins 1 and 20 at all times, even when the
IOC is sleeping (not being accessed by the
MCU).
§
Check the voltage at pin 28 of the IOC
081 AuxBus problem
(RF/U1). It should be between 5 and 6V. If it
is zero volts, you probably have a short
somewhere on the AuxBus line. Turn power
OFF, then measure pin 28 of U1 to ground.
If it is a short, pull the control board out to
see if the short is on that board.
§
If the voltage at pin 28 is between 5V and
6V, try pressing the BAND+ button a
number of times while watching the voltage
carefully (use an oscilloscope if possible).
The voltage should drop below 5V briefly if
the MCU (CTRL/U6) is sending a message
to the IOC. If the voltage does not change at
all, the MCU itself may not be sending
AuxBus messages.
§
Check the AuxBus signal at the MCU, pin
40 (CTRL/U6). If you don't see this voltage
drop below 5V briefly when the band is
changed, the MCU may not be functioning
(075).
§
090 EEPROM test #1 If you saw the message INFO 090 or INFO
091 on the LCD, one of the EEPROM write
failed
tests has failed.
§
091 EEPROM test #2 Check all voltages on the EEPROM
(CTRL/U7).
failed
§
Remove the control board and inspect U7
and surrounding traces. Verify that U7 is
properly soldered.
Receiver (100-149)
Problem
§
If you hear normal audio output on some
100 No audio output
from receiver bands but not all of them, check the band-
122
Troubleshooting Steps