Hitachi RAM-40QH5 Service Manual page 68

DISCHARGE PROCEDURE AND HOW TO CUT OFF POWER TO POWER CIRCUIT
Caution:
Voltage of about 360V is charged at both ends of smoothing capacitors 400 µF X 3.
G
High voltage (DC 360V) is also charged at screw and terminal sactions of system power module.
G
WARNING
During continuity check for each circuit of electrical parts in outdoor unit is performed, to prevent
G
secondary trouble, disconnect red/gray wire connected to system power module (SPM2) from
diode stack. (Also be sure to perform discharging of smoothing capacitor.)
1. Turn off the power switch of indoor unit or disconnect power plug.
2. Wait for 10 minutes or more after power is turned off and then remove electrical parts box lid. As shown
below, Apply soldering iron of 30-75W for 15 seconds or more to P1 and N1 black/white lead receptacles
on system power module to discharge voltage from smoothing capacitor.
Do not loosen or remove screws of system power module: If screw is loose, voltage will not be discharged.
3. Before operation check of each part of circuit, remove receptable of red/gray lead connected to system power
module from diode stack.
Screws of system power module (SPM2) are live parts: Do
not touch them. Screw tightening torque and method are strictly
specified.
When the screw is loosened or removed once, be sure to
tighten according to the procedure shown on the right, with
tightening torque of 0.8±0.2 N · m.
Smoothing Capacitors
(C501, C502, C503)
SPM2
Reactor
Diode stack Switching Power P.W.B.
(D25 VB60)
(For Indoor P.W.B)
Do not use soldering iron with
transfor mer: Doing so will blow
thermal fuse inside transformer.
As shown left, apply soldering iron to metal
parts (receptacles) in sleeve corresponding
to P1 and N1 terminals of system power
module (SPM2).
Service switch Control P.W.B.
– 74 –
Terminal
Board (4p)
Terminal
Power P.W.B.
Board (2p)