Hitachi UC 9SF Techical Data And Service Manual page 11

(3) Failure Mode (C) Steps and Repair Procedures
Too hot battery or adapter
Battery too hot?
NO
AC adapter too hot?
NO
The printed circuit board is
defective.
Replace the printed circuit
board unit.
YES
The battery is hot immediately
after full charging.
It's not a problem.
YES
Use a tester to check voltage.
Rated voltage on power
outlet?
YES
Replace the adapter.
-9-
Replace the battery.
NO
Apply rated voltage.
The rated voltage is AC 230 V.
A higher supply voltage may
break the adapter.