Ricoh FT7770 Service Manual page 567

Service Call 4 - Drum Overheat
o The drum temperature exceeds 60°C for more than 3 seconds.
Disconnect CN202
Is the drum thermistor a short circuit (CN202-B4, CN202-A1)?
Is the output of CN201-A16 on the main board always HIGH
(3 volts)?
N
Y
I
Is the output of CN301-B15 on the dc drive board
always LOW?
Y
Replace the dc drive board.
Replace the main board.
the drum thermistor.
Replace
N
I
Replace the ac drive board.
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30 April, '89