Hitachi RWM-(H)FSN3E, Service Manual

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11 Servicing
SMGB0070 rev. 1 - 08/2011
309
11
11.2.2 Replacing electrical components
D A N G E R
• Disconnect the Yutaki S from the power supply before touching any of the parts. Do not touch the electrical
box before disconnecting it in order to avoid an electrical shock.
• When handling the electrical box, take care of components. Do not apply excessive force to them, in order to
avoid damaging the electrical components.

Removing electrical box components
1 Remove electrical box cover, for accessing to the elec-
trical components (x4 screws).
Electrical box components
Item Part name Remarks
1
Printed circuit board
(PCB1)
Main printed circuit board for control of the unit.
2
Printed circuit board
(PCB2)
Secondary printed circuit board for additional
control signals.
3 Transformers (TR1/TR2) Current transformer.
4
Electrical heater
contactors (AR1/2/3)
Heater contactors for the control step and cut
off system.
5 Pump contactor (52P) Water pump contactor.
6 Noise filters (NK1~9) Noise filter for PCB current peak protection.
7
Electrical heater fuses
(EF1/2/3)
Fuses for electrical heater protection.
8 Water pump fuse (EF4) Fuse for water pump protection.
9 Terminal Board 1 (TB1) Terminal board for power supply.
10 Terminal Board 2 (TB2)
Terminal board for indoor/outdoor communica-
tion and Intelligent room thermostat and acces-
sory devices.

Replace electrical box
1 Remove Electrical box cover, for accessing to the electrical components (x4 screws).
2 Removing Electrical box:
• Step 1: Disconnect all external devices from Terminal
Board
• Step 2: Disconnect all internal unit devices inside elec-
trical box:
- Step 2a (Indoor unit devices 1)
Š
Electrical Heater power connection:
Disconnect AR2-2 wire
Disconnect AR3-2 wire
Disconnect AR3-4 wire
Disconnect TB1-N wire