Mitsubishi Electric Mr.Slim MUZ-GC25NA - C1, Service Manual

Page: 45 / 64

45
M How to check miswiring and serial signal error
Replace the indoor power P.C. board
and the indoor terminal P.C. board
Turn OFF the power supply.
Is there rated voltage in the
power supply?
Yes
No
Turn ON the power supply.
Check the power supply.
Is there rated voltage between
outdoor terminal block S1 and
S2?
No
Check the wiring.
Press EMERGENCY OPERATION switch once.
Does the upper lamp of OPERATION INDICA-
TOR lamp light up? <Con
fi rmation of the power
to the indoor unit>
Yes
No
Is serial signal error indicated 6 minutes later?
Yes
No
Is there any miswiring,
poor contact, or wire
disconnection of the
indoor/outdoor connect-
ing wire?
Yes
Correct them.
No
A
Turn OFF the power supply.
Check once more if the indoor/outdoor
connecting wire is not miswiring.
Short-circuit outdoor terminal block S2
and S3. 1
B
1. Miswiring may damage indoor electronic control P.C.
board during the operation.
Be sure to con
fi rm the wiring is correct before the opera-
tion starts.
Turn ON the power supply.
Does the LED on the inverter P.C. board or
the outdoor electronic control P.C. board
repeat "3.6-second-OFF and 0.8-second-
ON quick blinking"? 3
Yes
No
(Lighted
or not
lighted)
Replace the inverter P.C. board or the
outdoor electronic control P.C. board.
2
2. Be careful to the residual
voltage of smoothing capacitor.
Turn OFF the power supply.
Remove the short-circuit between out-
door terminal block S2 and S3.
Turn ON the power supply.
Is there amplitude of 10 to 20 V DC
between indoor terminal block S2 and
S3? <Con fi rmation of serial signal>
Is there rated voltage between indoor
terminal block S1 and S2?
<Con fi rmation of power voltage>
Yes
No
Is there any error of the in-
door/outdoor connecting wire,
such as the damage of the wire,
intermediate connection, poor
contact to the terminal block?
Yes
Replace the
indoor/outdoor
connecting wire.
Is there 2 VDC or less between CN10A (+)
and JPG (GND)(-) on the indoor electronic
control P.C. board?
No
No Yes
Be sure to release the failure-mode recall function after checking.
Yes
Turn OFF inverter-controlled lighting
equipment.
Turn OFF the power supply and then
turn ON again.
Press EMERGENCY OPERATION
switch. •
•
•
A
Is serial signal
error indicated 6
minutes later?
B
Yes
Reinstall
either the unit
or the light
each other
away.
Attach a
fi lter
on remote
control receiv-
ing section
of the indoor
unit.
•
•
No
3. Be sure to check this within 3 minutes after turning ON.
After 3 minutes, LED blinks 6 times. Even when the
inverter P.C. board or the outdoor electronic control P.C.
board is normal, LED blinks 6 times after 3 minutes.
Is there 2VDC or less between
CN10A (+) and JPG (GND)(-) on
the indoor electronic control P.C.
board?
Is there 2 VDC or less between
CN10A (+) and JPG (GND)(-) on
the indoor electronic control P.C.
board?
Replace the indoor elec-
tronic control P.C. board.
No Yes No
Yes
MUZ-GC25/35NA