Inspection Method 4 - Hitachi RAF-25NH4 Service Manual

nspection method 4
Check the number of times LD303 blinks.
Communications abnormally between microcomputers.
LD303A blinks
LD303A blinks once
External microcomputer
A internal unit 1
communications error
LD303A blinks twice
External microcomputer
A internal unit 2
communications error
LD303A blinks three
times *2
External microcomputer
A internal units 1 and
2 communications error
Check the internal P.W.B.
connected to the internal
unit in question. *1
The internal control P.W.B. is broken.
Replace the internal P.W.B..
LD303A blinks nine times
External microcomputer A
external microcomputer B
communications error
Check the internal P.W.B. connected
to the internal unit in question *1
abnormally
The internal control
P.W.B. is broken.
Replace the internal
control P.W.B..
Check to see that C1-D1
and C2-D2 are not
connected in reverse.
32-37V
Normal
Measure the voltage
of the C1-D1 and
C2-D2 terminal board.
Turn off the power source, and remove
the connecting cord of C1-D1 and C2-
D2. Then reconnect the power source,
and measure the voltage of the external
terminal board C1-D1 and C2-D2.
Check the switch power
source P.W.B. of the
external unit. *3
Check the external
unit control P.W.B..
Normal
abnormally
The external unit control P.W.B. is
broken. Replace the control P.W.B..
278
Normal
The external control
P.W.B. is broken.
Replace the external
control P.W.B..
Treat C1-D1 and C2-D2
as C3-D3, and check.
Normal
abnormally
The internal P.W.B.
32-37V
is broken. Reconnect
Normal
once of the internal
units, and replace
whichever of the
control P.W.B.s is
broken.
abnormally
The switch power
abnormally
source P.W.B. of the
external unit is
broken. Replace the
switch power source
P.W.B..
Normal
abnormally
The external unit
control P.W.B. is
broken. Replace the
control P.W.B..
LD303B blinks
LD303B blinks once
External microcomputer
A internal unit 3
communications error
LD303B blinks nine times
External microcomputer B
external microcomputer A
communications error