Checking Indoor Unit Electrical Parts; Power Does Not Come On (No Operation) - Hitachi RAS-50FH7 Service Manual

CHECKING INDOOR UNIT ELECTRICAL PARTS

MODEL RAC-50YH7

1. Power does not come on (no operation)

Is DC 35V being generated between
terminals C and D on the terminal
board?
Are control voltages (12V, 5V)
being generated normally?
Yes
Do the air deflectors perform initial
operation when the power supply is
turned on and off?
No
Is the microcomputer reset input
(pin 7 )"Hi" ?
Yes
Is the microcomputer clock signal
10MHz at pin being
10 11
generated normally?
Yes
Replace the control P.W.B
No
Is AC 220-240V AC being generated
between terminals L and N on the
outdoor unit terminal board?
Is DC 35V being generated between
terminals C and D on the outdoor
unit terminal board?
No
No
Yes
No
No
Perform final operation check.
– 84 –
No
Check AC outlet and breaker, and
repair any defective part.
Yes
Yes
Check the indoor/outdoor unit
connection cable, and correct any
defective section (wrong connection,
incomplete insertion reversed).
Check the outdoor unit power circuit,
and repair the defective section.
Check according to the proper method
for checking the power circuit.
Check the indication P.W.B.
connection cord and light receiving
unit.
Check the reset circuit, and repair
any defective section.
Replace the microcomputer and
oscillator.