
・
The equipment is high-voltage. Therefore guard particularly against electric shocks. Guard also against short-
circuits due to erroneously connected measuring equipment. The board would otherwise become destroyed.
(5) NF coils for C001, C002, C004, C005
These absorb electrical noises generated during a
compressor run. At the same time, they absorb external
noises coming in through the power line, thereby protecting
the electronics parts.
(6) Surge absorber and varistors 1 and 2
These absorb induced lightning and other external surges.
※
Be sure to ground the outdoor unit.
If ungrounded, the noise filter mentioned above will not
function normally.
※
If the outdoor unit remains ungrounded, the "surge
absorber" and "varistor 1" will not function.
Be sure to ground the equipment.
2. Board-purpose power supply circuit
The voltage specifications for the power supply circuit are as follows:
[Checkpoints]
5 V
12 V
15.5 V
12 V
B-12 V
output
±1
±0.4
±1.5
+3
−1
Typical failure modes conceivable in an output failure
(Ref)
Specified
voltage
measuring locations
Main load
Output
name
Microcomputers
IC2, 3, and 4
Relay circuit
Microcomputer
Thermistor
Compressor-purpose IPM
IPM for DC fan
Expansion valve
±
5 V output
・
Check the corresponding voltage. If it satisfies the above voltage specifications, the board-purpose power supply circuit
should be normal.
12 V output
16 V output
Tester positive terminal: R18 (5 V display)
Tester negative terminal: J17 (0 V display)
Tester positive terminal: J21
(
16Vdisplay)
Tester negative terminal: J17
(
0Vdisplay
)
Tester positive terminal: J20 (12 V display)
Tester negative terminal: J17 (0 V display)
Tester positive terminal: J9
(
B-12V display
)
Tester negative terminal
:
J7
(
B-0V display
)
Failure diagnosis lamp LD301
Failure diagnosis lamp LD301
Failure diagnosis lamp LD301
Failure diagnosis lamp LD301
Outdoor unit inoperable with no display
Outdoor unit inoperable with no display
Blinks 3, 4, or 12 times and stops.
Blinks 5 times and stops.
– 184 –
CN30 FOR SELF-CHECK
LD301
LD302
LD303
CONTROL P.W.B.
TEST SWITCH
OUTDOOR FAN
MOTOR CONNECTOR
IPM
DC VOLTAGE
MESUREMENT
POINT(+)
DC VOLTAGE
MESUREMENT
POINT(-)