Ricoh FT4480 Field Service Manual page 231

15 March 1987
53 FUSING THERMISTOR ABNORMAL
- Possible Causes -
• Thermistor failure (The input at CN206-B1 is less than 0.5 V.)
- Action -
Replace the fusing thermistor.
5 4 F U S I N G W A R M - U P F A I L U R E
- Possible Causes -
• Fusing lamp blown
• Thermistor circuit open
- Action -
SC 54 turns on if the hot roller does not reach 150°C within 8 minutes
after the power relay turns on.
Is the fusing lamp filament broken?
Y N
I
Is the thermistor circuit open?
Y N
I
Check the thermistor. Make sure it is mounted properly and in
good contact with the hot roller.
Replace the thermistor.
Replace the fusing lamp.
5 5 F U S I N G O V E R H E A T
- Possible Causes -
• Thermistor failure (CN206-B1 < 0.5 V)
- Action -
Replace the thermistor.
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