Ricoh FT5580 Service Manual page 182

12 June 1987
Code #53: Thermistor Blown
Definition
Lights if the fusing thermistor is open or shorted.
Observation
Code #53 is displayed immediately after the main switch is turned on.
Points to Check
Disconnect the white thermistor connector on the front side of the fusing
unit. Check the resistance of the thermistor at the white connector.
- Reference value: 1.10 kohms at 180°C 180 kohms at 10°C
Code #54: Ready Signal Not On
Definition
Lights if the idle signal is not received within 8 minutes after the power
relay turns on.
Observation
The fusing lamp does not turn on. The ready beeper does not sound and
code #54 is displayed 8 minutes after power is turned on.
Points to Check
Check the power relay, fusing lamp, ac drive board, and operation panel
board.
T o c o n t r o l e f f e c t s o f e l e c t r i c a l n o i s e f r o m s u r r o u n d i n g m a c h i n e s , t r y
JP100.
Check for poor contact in the fusing unit connector.
Code #55: Fusing Overheat
Definition
Lights if the voltage at CN103-4 (fusing thermistor) drops below 0.53 V
for 0.4 second.
Observation
The fusing lamp stays on after the temperature rises above 220°C.
Points to Check
Check the voltage at CN504-1 on the ac drive board for line voltage.
Check the resistance of the thermistor.
Disconnect the white thermistor connector on the front side of the
fusing unit.
Reference value: 1.10 kohms at 180°C 180 kohms at 10°C
10-6