Discharge Procedure And Power Shut Off Method For Power Circuit - Hitachi RAK-25NH4 Service Manual

DISCHARGE PROCEDURE AND POWER SHUT OFF METHOD FOR POWER CIRCUIT

Caution
Voltage of about 300-330V is charged between both ends of smoothing capacitors
During continuity check for each part of circuit in indoor unit electrical parts, disconnect red/gray
WARNING
lead wire connected from diode stack to system power module (SPM2) to prevent secondary
trouble. (Be sure to discharge smoothing capacitor)
1. Turn OFF the Power supply to the outdoor unit.
2. After power is turned off, wait for 10 minutes or more. Then, remove electrical parts cover and apply soldering
iron of 30 to 75W for 15 seconds or more to P2 and N1 terminals on system power module, in order to
discharge voltage in smoothing capacitor.
3. Remove receptable of red/gray lead wire connected to system power module from diode stack before
performing operation chech of each circuit.
P1
N1
System power module
RAC-25NH4, RAC-35NH4
SPM2 Smoothing capacitors
RAC-50NH4
Smoothing capacitors
SPM2
Soldering
iron
– 97 –
Do not use a soldering iron with
transformer: If one is used, thermal fuse
inside transformer will be blown
As shown above, apply soldering iron to metal
parts (receptable) inside the sleeve
corresponding to P1 and N1 terminals of
system power module: Do this with smoothing
capacitors kept connected. By removing red/
gray lead wire from diode stack, power supply
can be shut off. (corresponding to + and –
terminals of system power module)