Mitsubishi Electric PQHY-P120THMU-A, Service Handbook

Page: 258 / 414

[
IX
Troubleshooting ]
- 249 - HWE09080 GB
1. Error Code
Abnormal bus voltage drop (Detail code 108)
2. Error definition and error detection method
If Vdc 160V or less is detected during Inverter operation. (S/W detection)
3. Cause, check method and remedy
(1) Power supply environment
Check whether the unit makes an instantaneous stop when the detection result is abnormal or a power failure occurs.
Check whether the power voltage is 188V or less across all phases.
(2) Voltage drop detected
4220
Œ
Check the voltage between the tab terminal TB-P and TB-N on the INV board while the inverter is stopped. -> Check the fol-
lowing items if it is 253V or above.
1) Confirm on the LED monitor that the bus voltage is above 160 V.
Replace the INV board if it is below 160 V.
2) Check the voltage at CN505 on the control board. ->Go to (3).
3) Check the coil connections (L1 - L3) and for coil burnout.
4) Check the wiring connections between the following sections
Between the noise filter board and INV board. Between the INV board and DCL. Between the INV board and C1.
Replace 72C if no problems are found.-> Check the following items if the voltage is below 253V.
1) Check the coil connections (L1 - L3) and for coil burnout.
2) Check the wiring between the noise filter board and INV board.
3) Check the connection to SC-P1 and SC-P2 on the INV board.
4) Check the in-rush current resistor value. Replace the INV board if no problems are found.
(3) Control board failure
Check that 200 VAC is applied to connector CN505 on the control board while the inverter is operating. If voltage is absent or
the wrong voltage is applied, check the fuse F01. Replace the control board if no problems are found with the fuse.
Refer to section -6- "Inverter (THMU-A)" under part [4] Troubleshooting Principal Parts for error codes related to the
inverter.(page 328)
4220 (THMU-A)