Service manual

Si18-201 Troubleshooting - Outdoor Unit Related
Service Diagnosis 303
3.4.6 Power Transistor Check (Capacitor Voltage Check)
Check No.6 Power Transistor Check
"
Do not touch the charging unit for 10 minutes after turning the breaker off.
"
Even when touching the charging unit after 10 minutes, use a multiple meter to ensure that
the power supply voltage of power transistor is 50V or less.
"
Measure U,V,W either on terminals of control PC board on the substrate side or on the
compressor terminals.
"
Measure (+),(–) of the power transistor on (+) / (–) section of capacitor as shown in the figure
below.
∗
If the resistance value is not normal, replace the control PC board.
Capacitor Voltage Check
"
Follow the below figure to measure the capacitor voltage with breaker kept ON, while take
enough care not to touch the charging unit .
Negative (–) terminal of tester
(positive (+) terminal for digital
type)
(+) of power
transistor
UVW (–) of power
transistor
UVW
Positive (+ terminal of tester
(negative (–) terminal for digital
type)
UVW (+) of power
transistor
UVW (–) of power
transistor
Normal resistance
∞
Several K
Ω
to
several M
Ω
Several K
Ω
to
several M
Ω
∞
Resistance for NG 0 0 to several
Ω
0 to several
Ω
0