Power Transistor Check - Daikin CTXU25G2V1B Service Manual

SiBE12-908
3. Diagnose method (Diagnose can be made according to 6 LEDs lighting status as
(1) When all LEDs are lit uniformly, → Compressor malfunction (to be replaced)
(2) When some of LEDs are not lit (LEDs are not lit or go off, etc.):
∗
∗
If NG : → The power transistor may have a failure. (Replace the power transistor).
If the power transistor is normal, check if there is any solder cracking on the filter PCB.
∗
∗
Caution
3.9

Power Transistor Check

Check No.15
(–) terminal of a tester
(+) terminal of a tester
Resistance in OK
Resistance in NG
Service Diagnosis
follows:)
Check the individual power transistor. (Refer to check No.15)
When the power transistor and control PCB are integrated :
→
Replace the control PCB.
When the power transistor can be checked individually :
↓
Check the resistance value. (Refer to check No.15)
If any solder cracking is found: → Replace the filter PCB (or repair the soldered section).
If the filter PCB is normal: → Replace the control PCB.
When the output frequency is low, the LED flashes slowly. As the frequency increases, the
LED flashes quickly. (It looks like the LED is lit)
If the operation is carried out with no load (the condition of the compressor is disconnected),
some of units may stop operation with "CT system error" (due to no electric current) or
"startup failure" (because the compressor does not turn). In this case, check if the LED is
flashing during "operation" to "malfunction stop". (Refer to the service manual of each air
conditioner for checking whether the alarm LEDs for CT system, startup failure, etc. are
provided or not.)
On completion of diagnose by this checker, be sure to re-crimp the FASTON terminal for
resetting the system.
(Otherwise, the terminal may be burned due to loosening.)
Do not touch the live parts within 10 minutes after the breaker is turned off.
Even after that, when you touch the parts, check to see that supply voltage of the power
transistor is less than 50 V with a tester.
Measure resistance at connector terminal on PCB or at the relay connector.
Power transistor
Direction of crimp
FASTON terminal
UVW
(+)
Power transistor
UVW
(+)
several kΩ~several MΩ
This size is shortened
by "crimp".
Power transistor
(–)
Power transistor
UVW
∞
0 or
Check
(R5161)
UVW
(–)
174