Daikin VRV RXYQ72-384XAYCA, Service Manual

Page: 192 / 419

Field Settings for Outdoor Unit SiUS342004EB
185 Part 5 Field Settings and Test Operation
[2-28]: Power transistor check mode
To evaluate the output of the power transistors. Use this function in case error code
is displayed related to defective inverter PCB or compressor is locked.
Default value: 0. Power transistor check mode is not active.
Field setting 1: Power transistor check mode is active.
Function:

Inverter PCB gives output of 10 Hz in sequence by all 6 transistors. Remove the
U/V/W terminals of the compressor, and connect to the inverter checker module. If
all 6 LEDs blink, the transistors switch correctly.

When the power transistor check mode is interrupted, after internal power circuit
is disconnected on the inverter PCB, 2 LEDs will light up to indicate discharge of the
DC voltage. Wait till the LEDs are OFF before returning fasten terminals back to the
compressor terminals.
Minimum requirements to refer to the result on the inverter checker module:

All 3 phases and neutral are available, and

Inverter PCB control is active. Check if the green LED “HAP” on the inverter PCBs
are blinking normal (approx. 1/second). If LEDs are OFF, need to exit the “standby
mode” of the inverter:

Disconnect and reconnect power supply control PCB, or

Forced thermostat ON condition, or

Make shortly set 2-6-1 (forced thermostat ON indoor), or 2-20-1
(manual refrigerant charge).

Once the LED is blinking on the inverter PCB, change related setting
immediately back to set 0 to deactivate related function.

Diode module generates the required 750 VDC.
Cautions:

In case there is more than 1 compressor in a system (outdoor is multi outdoor
configuration) all compressor inverter PCBs will perform the power transistor check.
In such case, disconnect U/V/W fasten terminals on all compressors. Avoid
accidental touch of fasten terminals to short circuit or ground leak to casing.

To stop the power transistor check mode, change setting to default 2-28-0.

Output to U/V/W will also stop when outdoor unit main PCB decides standby
mode of inverter circuit.