Mitsubishi Electric PU(H)Y-P250YGM-A, Service Handbook

Page: 172 / 215

- 163 -
[
IX
Troubleshooting ]
(6) Diode stack
Measure resistances between each pair of terminals on the diode stack with a tester, and use the results for troubleshoot-
ing.Refer to (5) " Intelligent power module (IPM) " for notes on measurement and tester selection.
(7) Caution at replacement of inverter parts
1) Check for miswiring and loose connections.
Incorrect or loose wiring of such circuit components as IPM and diode stack may cause the IPM damage. Thoroughly
check the wiring. Retighten all screws upon completion of all other work.
Connect the IPM control terminal carefully to the G/A board, as the terminal is very small.If the output wire from the
IPM to the compressor is connected incorrectly, the compressor will be damaged. Perform wiring carefully in order of
color shown in the wiring diagram below.
2) Coat the radiation surface of the IPM and diode stack evenly with the grease that is provided with the service parts.
Apply a thin layer of grease to the entire surface of the back of the IPM and diode stack, and screw the module securely
into place.
Wipe off any grease that may get on the wiring terminal to avoid terminal contact failure.
Judgment value (reference)
Black ( + ) External view
+ (P) - (N) to (L1) to (L2) to (L3)
Red (-)
+ (P) - - 5 - 200
ohm 5 - 200
ohm 5 - 200
ohm
- (N) - -
to (L1) 5 - 200
ohm - - -
Internal circuit diagram
to (L2) 5 - 200
ohm - - -
to (L3) 5 - 200
ohm - - -
L1 L2 L3
+
-
L1
L2
L3
Red
Red
White Black
Black
U V
N
P
W IPM
Capacitor
To compressor
G/A board