Inverter Pcb Replacement Procedure - Mitsubishi Heavy Industries FDT28KXE6A Service Manual

2.5 Inverter PCB replacement procedure

Exchange the inverter pwb according to the following procedure.
1. Exchange the pwb after elapsing 3 minutes from power OFF.
(Be sure to measure voltage (DC) of two places (1. Power supply for pwb 2. Power supply for fan motor) and
check that the voltage is discharged sufficiently. (Refer to Fig.3 next page))
2. Disconnect the connectors from the pwb.
3. Exchange the pwb.
4. Match the setting switches (JSW10, 11) with the former pwb. (Refer to Table.1)
5. Connect the connectors, wiring, and snubber capacitor. (Contirm the connectors are not half inserted.)
6. Cautions for maintenance of the control box
This control box has its front part hinged so as to be able to open and close for maintenance of the inverter.
Following cautions must be observed during the maintenance.
Always follow the instructions described in the technical manual when implementing the maintenance.
(1) Turn off the power supply before starting the maintenance.
(2) After waiting for minimum 3 minutes after turning off the main power supply, measure the DC power supply voltage
(between F1 and DS (-) of the control power supply) to confirm according to the technical manual that the electricity
has been discharged sufficiently.
Only then disconnect the power supply cable and the signal cable from the terminal board.
(3) Remove a total 8 pieces of screw at the sections A, B and C in Figure 1.
• Take care not to drop screws on the PCB, etc. when removing them.
• Make sure to collect when dropped any.
(4) Open the front part of the control box as shown in Figure 2.
• Don't open the front part more than 90º.
• Avoid exerting undue force on the open front part.
• Provide a support under the open fuont part.
(5) After opening the front part of the control box, you can access to the inverter. Start the maintenance according to the tech-
nical manual.
• When a tie wrap band has been cut off, fix it firmly at the original position with a new tie wrap band.
• When a connector has been disconnected from the PCB, insert firmly the connector again at the original position.
• Some of electrical parts are designed specifically to INV1 or INV2.
They are stamped or indicated with the lead mark to which of INV1 or INV2 they are used.
Take care not to use wrong parts duing repair.
If wrong parts are used, the equipment will not operate properly.
(6) When the maintenance is over, close the front part of the control box as shown in Figure 3.
• Take care not to nip the wiring with the front part.
(7) Reinstall and tighten the 8 screws removed at the sections A, B and C.
Don't overlook to tighten the screws at the sectiong B particularly.
• Take care not to drop screws on the PCB, etc. when tightening them.
• Make sure to collect when dropped any, and tighten them at proper positions.
(8) Confirm visually that all screws have been tightened, and all cables have been connected properly.
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