Toshiba RAS-18YKH-E Service Manual page 32

9-3-4. How to Check the P.C. Board
(1) Operating precautions
1) When removing the front panel or the P.C.
board, be sure to disconnect the power plug
from the AC outlet.
2) When removing the P.C. board, hold the edge
of the P.C. board and do not apply force to the
parts.
3) When connecting or disconnecting the
connectors on the P.C. board, hold the whole
housing. Do not pull at the lead wire.
(2) lnspection procedures
1) When a P.C. board is judged to be failure,
check for disconnection, burning, or discol-
oration of the copper foil pattern or this P.C.
board.
2) The P.C. board consists of the following 4
parts:
No. Procedure
1 Disconnect the power plug from the
AC outlet and remove the P.C. board
assembly from the elec tronic parts
base.
Remove the flat cable from the
terminal plate.
2 Turn the power ON.
If the OPERATION lamp flash (0.5
sec. ON, 0.5 sec. OFF), steps 1–3 in
the right column are not necessary.
3 Push the START/STOP button once
to set in operation mode.
(Do not set to the fan only or on-
timer mode.)
4 Start operation by using the
antirestart timer.
a. Main P.C. board part:
Power relay, indoor fan motor drive circuit and
control circuit, C.P.U. and peripheral circuits,
buzzer drive circuit and buzzer.
b. Infrared rays receive parts:
Infrared rays receiving circuit
c. Display:
LED
d. Switch P.C. board:
Wireless-control, TEMPORARY switch
e. Buzzer P.C. board:
Buzzer
f. Transformer P.C. board:
Transformer
Check the defects of the P.C. board following the
list below. (Referring to Table 9-3-1)
(3) Checking procedure
Table 9-3-1
Check point (Symptom)
ls the fuse blown?
Check power supply voltage.
1. Between CN12 1 and 3
(220–240V AC)
2. Between CN01 1 and 3
(12V AC)
3. Between TP6 (+5V) and GND
(5V AC)
4. Between TP7 (+12V) and GND
(12V DC)
Check power supply voltage.
1. Between terminals 2 and 3
2. Between terminals 1 and 2
1. All LEDs of the OPERATION lamp, the
TIMER lamp, PRE DEF. lamp,
ECONO. lamp and AUTO lamp light
up.
2. After 3 seconds, normal display does
not appear.
– 32 –
Trouble cause
1. Application of shock voltage
2. Short-circuit of the indoor fan
motor
1. Defective power cord, power
switch, fuse or line filter, or
wrong wiring
2. Defective power transformer
3. Defective power circuit or
short-circuited load
4. Same as 3
5. Thermal fuse operation
1. Miswiring
2. PF terminal is failure.

Display is failure or

defect in the 9P

housing assembly.