Mitsubishi Heavy Industries SRK25GZ-L1 Handbook page 220

SCM-HG (2 room)
(7) Outdoor unit inspection points
CAUTION – HIGH VOLTAGE
High voltage is produced in the control box. Don't touch
electrical parts in the control box for 5 minutes after the unit is
stopped.
¡Power source and serial
signal inspection
1 to 2: AC220/240V
2 to 3: Normal if the voltage oscil-
lates between DC 0 and
approx. 12V
BK
1
WH
2
UNIT A
RD
Serial A
3
BK
1
WH
UNIT B
2
BL
Serial B
3
BK R. IN
Power source
1
WH
1 Phase
S. IN
2
220/240V
Y/GN
50Hz
Y/GN
G
¡Inspection of electronic expansion valve
To test if there is voltage.
(Voltage is only applied to the electronic expansion valve when the valve angle is
being changed.)
Red to white
Red to Orange
Brown to yellow
Brown to blue
If the expansion valve does not operate as shown above, it is defective.
Power transistor inspection procedure
[Use a tester with a needle indicator for the inspection. (Do not use a digital tester. Check in the AC 300 volt range.)]
(1) If there is a self-diagnosis display, inspect the compressor system (burns, wiring mistakes, etc.). If no problems are found,
check the output of the power transistor.
(2) Output inspection procedure
Disconnect the terminals for the compres-
sor. If an output such as the one shown in
the figure on the right can be measured,
the power transistor and the circuit board
for the outdoor unit are normal.
For about 50 seconds. After being switched on,
there will be a delay of approximately one minute
depending on the conditions.
218
BL
AC·R
52X2-4
GY
AC·S
S. OUT
Fuse
250V 25A
CNB CNB
Printed circuit board
CNA
20S
}
Normal if there is approximately DC 5 V 10 seconds
after the power supply is turned on.
Output voltage
(ACV)
¡Display lamp inspection
• LED 2 (Abnormality display lamp - Red)
• LED 1, 3 to 6: (Light display for each
room - Green)
Inspection of reactor conductivity
Remove the connector and check for
conductivity.It must be conductive.
L
WH OR
~ +
+ + +
IC2
~ –
DS
LED1 LED3 LED2
(Green) (Red)
Printed circuit board
CNE CNF CNA
EEVA EEVB FMo
Inspection of resistance value of Comp. dome
thermistor
Remove the connector and check the resistance value.
See the section of thermistor characteristics on page 213.
0
8 ~ 10 sec.
1
Operation SW ON
ON or flashing: Protection function operating
ON when there is a serial signal being
received among each of the indoor units.
OFF during ignition, stop abnormality.
Power
transistor
U RD
P
V WH
+
CM
W BK
N
CNC
CND
Tho-A Tho-R Tho-D
(Example)
Self-diagnosis display : Flashes 2 times
Measure in this section