2WA/2NJ/2RK
7-480
F020: System memory error (RAM reading/writing error or CPU memory error)
The error appears during the reading/writing check of the RAM for the CPU when the main unit starts up.
F021: System memory error (RAM reading/writing error or ASIC memory error)
The error appears during the reading/writing check of the RAM for the main PWB ASIC when the main unit
starts up.
8 Replacing the main PWB The main PWB is faulty. Replace the main PWB. Detaching
and Reat-
taching the
main PWB
Step Check description Assumed cause Measures Reference
1 Resetting the main power The communication
between the main PWB
and the operation panel
main PWB is faulty.
Remove the original and
check the sensor. Next, turn
off the power switch and main
switch. Then, turn on the
main switch and power
switch when passing 5 sec-
onds.
2 Executing U021 The backup RAM data is
faulty.
Execute U021 to initialize the
backup RAM data.
Executing
U021
3 Checking the main PWB The connector or the FFC
is not properly connected.
The wire, the FFC or the
PWB is faulty.
Clean the connectors on the
main PWB and the FFC ter-
minal. Then, reconnect the
wire connector and the FFC.
At that time, if the wire is
pinched by other parts or it is
damaged, repair or replace
the wire. If the FFC terminal
section is deformed or FFC is
broken, replace the FFC. If
the issue is not resolved,
replace the main PWB.
Detaching
and Reat-
taching the
main PWB
Step Check description Assumed cause Measures Reference
1 Resetting the main power The main PWB does not
properly start up.
Remove the original and
check the sensor. Next, turn
off the power switch and main
switch. Then, turn on the
main switch and power
switch when passing 5 sec-
onds.
2 Executing U021 The backup RAM data is
faulty.
Execute U021 to initialize the
backup RAM data.
Executing
U021
Step Check description Assumed cause Measures Reference
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