Mitsubishi Electric MSH-07NV Service Manual page 54

How to check mis-wiring and serial signal error (when outdoor unit does not work)
E
MSH-24NV
Repair wiring.
3 minutes later,is there DC 20V between both ends
of R132?
( By tester, the stylus is between 0 ~ 20V. )
Yes
•Turn OFF power supply.
•Connect ON in-out connecting wire.
•Turn ON power supply.
Is there AC220~240V between outdoor terminal blocks
3 minutes later, when EMERGENCY OPERATION
switch is pressed is there DC 5V between J8
on outdoor DEICER P.C. board?
3 minutes later, when EMERGENCY OPERATION
switch is pressed and 52C relay turns on, is there
DC 10V between both ends of R601?
(By tester, the stylus is between 5 ~10V)
Replace the outdoor DEICER P.C. board.
54
1. Turn OFF power supply.
2. Turn ON power supply.
3. Press EMERGENCY OPERATION switch.
3 min. later, what self-check result is displayed on OPERATION
INDICATOR lamp on indoor unit? 1
Yes
Is there in-out mis-wiring, poor contact, or wire disconnection?
1. Turn OFF power supply and disconnect in-out connecting wire on indoor side.
2. Short-circuit between indoor terminal block
3. Turn ON power supply and press EMERGENCY OPERATION switch.
No
-
N
2
Yes
No
+ -J7 –
Yes
No
Yes
Start
Mis-wiring is indicated.(0.5-sec.ON, 0.5-sec.OFF)
No
and
N 3
No
?
1 Short circuit of JPG and JPS on the
indoor electronic control P.C. board
enables self-check to be displayed in 3
seconds.
Serial signal error is indicated.
(0.5-sec.ON, 2.5-sec.OFF)
Replace the indoor electronic control
P.C. board.
Replace in-out connecting wire of
and .
2 N
Check and rectify fuse and varistor on out-
door DEICER P.C. board.
Replace
3 in-out connecting wire.