Mitsubishi Electric CITY MULTI PUHY-P200YEM-A Service Handbook page 99

(In the case of M-NET remote controller)
Symptom
1 Despite pressing of
remote controller
ON/OFF switch,
operation does not
start and there is no
electronic sound.
(No powering signal
appears.)
2 At about 10 seconds
after turning remote
controller operation
switch ON, the
display distinguishes
and the operation
stops.
Checking method & countermeasure
Check indoor LED3
Lighting?
Lighting
Check for the change of LED
display by operating dip switch
SW1 for self-diagnosis.
1 Check the transformer in accordance with the "TROUBLE SHOOTING" in the indoor unit's service handbook.
Cause
1) M-NET transmission power source is not supplied
from outdoor unit.
1 Main power source of outdoor unit is not
connected.
2 Disconnection of connector on outdoor unit circuit
board.
Main board : CNS1, CNVCC3
INV board : CNAC2, CNVCC1, CNL2
3 Faulty power source circuit of outdoor unit.
• Faulty INV board,
• Blown fuse (F1 on INV board)
• Broken diode stack
• Broken resistor (R1) for rush current protection
2) Short circuit of transmission line.
3) Erroneous wiring of M-NET transmission line at outdoor unit.
1 Transmission line disconnection or slipping off from terminal
block.
2 Erroneous connection of indoor/outdoor transmission line to
TB7.
4) Disconnection of transmission wiring at remote controller.
5) Faulty remote controller.
1) Power source is not fed to indoor unit from transformer.
1
Main power source of indoor unit is not turned on.
2
Disconnection of connector (CND, CNT, CN3T) on indoor controller board.
3
Blown fuse on indoor controller board.
4
Faulty or disconnected transformer of indoor unit.
5
Faulty indoor controller board.
2) Faulty outdoor control circuit board uncontrolled.
As normal transmission is fails between indoor and outdoor units, outdoor unit model can not be
recognized.
Check indoor unit
power source terminal
block voltage
AC 220~240V?
Extinguishing or
unable to confirm Check fuse on circuit
board
Check connection of con-
nector (CND, CNT, CN3T)
Disconnected
Check transformer
resistance value
Within rated?
Check self-diagnosis
function of outdoor unit
Faulty indoor
controller board
NO
Check main power source
of power source wiring.
YES
Check 220V~240V
YES
circuit for short circuit
Blown?
and ground fault.
NO
YES
NO
1
Check cause of trans-
former disconnection.
NO
•Ground fault on circuit
•Ground fault on
YES
NO
Changed?
Check self-diagnosis function af-
ter powering outdoor unit again.
Changed?
YES
YES
Accidental
trouble
- 98 -
Checking method & countermeasure
a) Check transmission terminal block of
remote controller for voltage.
i) In case of 17 ~ 30V
Faulty network remote controller
ii) In case of less than 17V
See "Transmission Power Circuit
(30V) Check Procedure".
The cause of 2) and 3) is
displayed with self-diagnosis
LED for 7102 error.
Improper connector
connection
board
sensor, LEV
NO
Faulty outdoor unit
control circuit board
Apply power
source again.
Repair
faulty point.