Hitachi RAM-90QH5, Service Manual, Page: 79 / 83

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HOW TO CHECK POWER MODULE
Checking power module using tester
Set tester to resistance range (X 100)
If indicator does not swing in the following conductivity check, the power module is normal.
(In case of digital tester, since built-in battery is set in reverse direction, + and – terminals are reversed.)
CAUTION
If inner circuit of power module (IPM) is disconnected (open), the indicator of tester will not swing and this may assumed as
normal. In this case, if indicator swings when + and – terminals are connected in reverse of diagram below, it is normal.
Furthermore, compare how indicator swings at U, V and W phases. If indicator swings the same way at each point, it is
normal.