Example Of Indoor P.w.b. Checking Method - Hitachi RAF-25NH4 Service Manual

* 1 Example of indoor P.W.B. checking method (when indoor unit 1 is displayed as broken)
Reinsert the connecting cord of indoor unit 1 (the indoor unit with a communications error) and indoor unit 2 (the indoor unit
where communications are possible) (turn off the power source before disconnecting and reinserting the connecting cord)
indoor unit 2 communications error
LD303 blinks twice
The indoor unit control
P.W.B. is broken.
* 2 This breakdown check assumes an indoor unit is connected to all four rooms (or all three rooms). If an indoor unit is not
connected to all four rooms (or all three rooms), note that there will be either blinking to indicate a communications error
for the unconnected indoor unit or three blinks when there is a communications error for the connected indoor units.
* 3 Indoor unit switch power source P.W.B. check method
Is the 3A fuse
broken?
Yes
The switch power source
P.W.B. is broken.
The switch power source
P.W.B. is broken.
Install CN9A, and
check the voltage
f o r B E N - 1 2 V - A
and BEN-5V-A.
abnormally
Check the
expansion valve.
Normal
There is a chance that
the switch power source
control P.W.B. is broken.
Replace the switch power
source control P.W.B..
No
U s e I / F 0 V - A a s a
standard for checking
the voltage for 35V-A,
BEN-12V-A and BEN-
5V-A.
R e m o v e C N 8 a n d
abnormally
C N 9 A , a n d c h e c k
the voltage for 35V-
A, BEN-12V-A and
BEN-5V-A.
Normal I n s t a l l C N 8 , a n d
check the voltage for
35V-A, BEN-12V-A
and BEN-5V-A.
There is a chance that the
control P.W.B. interface
relay, interface transistor,
NF coil or indoor unit 1,
indoor unit 2 is broken.
indoor unit 1 communications error
LD303 blinks once
The indoor unit control P.W.B. is not broken.
Check the outdoor unit control P.W.B..
Normal
U s e I / F 0 V - B a s a
s t a n d a r d f o r
checking the voltage
for 35V-B, BEN-12V-
B and BEN-5V-B.
abnormally
R e m o v e C N 8 a n d
C N 9 B , a n d c h e c k
the voltage for 35V-
B, BEN-12V-B and
BEN-5V-B.
Normal
Install CN8, and check
the voltage for 35V-B,
BEN-12V-B and BEN-
5V-B.
abnormally
There is a chance that the
control P.W.B. interface
relay, interface transistor,
NF coil or indoor unit 3,
indoor unit 4 is broken.
280
Normal
The switch
power source
P.W.B. is normal.
abnormally
abnormally
The switch power
source P.W.B. is
broken.
Normal
Normal
Install CN9, and
c h e c k t h e
voltage for BEN-
12V-B and BEN-
5V-B.
abnormally
Check the
expansion valve.
There is a chance that
t h e s w i t c h p o w e r
source control P.W.B.
is broken. Replace the
switch power source
control P.W.B..
abnormally
Normal