Daikin BPMK928B42, Service Manual

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Troubleshooting - Outdoor Unit Related Si18-201
304 Service Diagnosis
3.4.7 Power Transistor Output Check
Check No.7 Measure the output current and voltage of the power transistor.
Output Current
Measurement Remove the front panel, and measure the current in the red, yellow and blue wire harness
inside the compressor using a clamp meter.
1. Attach the clamp meter to the red, yellow and blue wire harness, and conduct forced cooling
operation.
2. When the output frequency has stabilized, measure the output current of each phase.
3. If the current outputs of all the phase are balanced, it is normal.
4. If even one phase is out of balance, replace the outdoor unit PCB.
5. If the compressor stops before the output frequency stabilizes, measure the output voltage.
Output Voltage
Measurement Remove the front panel, and disconnect the red, yellow and blue wire harness inside the
compressor from the terminals. Measure the output voltage of the red, yellow and blue wires
using a tester.
1. Conduct forced cooling operation with the equipment in the condition shown in Fig.1.
2. Measure the voltage between the operation start (when the outdoor unit fan starts rotating)
to operation halt caused by an stall prevention (about 5 seconds).
3. Reset the power, and repeat steps (1) to (3) for each phase of U-V, V-W and W-U.
4. If the voltages of all the phases show results similar to the solid line in the graph shown in
Fig.2, the outdoor PCB is normal.
5. If the voltage of even one phase deviates from the solid line shown in Fig.2, conduct the
following test.
"
Check the harness between the power transistor and compressor (check items: breaking of
wire and wiring errors). If the harness is normal, replace the PCB..
Note: 1. Do not touch the terminals of the red, yellow and blue wires when the power is supplied.
(Touching them is very dangerous since a voltage of over 100V is applied.)
2. Do not short-circuit the terminals of the red, yellow, and blue wires.
[Fig.1] [Fig.2]
AC
25
(V)
2 second 5 second
3 min.