Ricoh FT5034, Service Manual

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2. Fusing Temperature Control
This machine controls the fusing temperature based on a zero cross signal.
After the main switch is turned on, the fusing lamp remains lit until the temperature
reaches 165°C. Then fusing lamp control shifts to ON/OFF control until the fusing
temperature reaches the operating temperature (185°C). The fusing lamp turns on or
off at the falling edges of the zero cross signal. By using this ON/OFF control system,
fusing temperature overshoot is reduced. When the temperature reaches the ready
temperature (180°C), the Start key turns from red to green and the beeper sounds
three times.
In the energy saver mode, the fusing temperature is kept at 175°C.
The fusing lamp maintains its ON or OFF condition while the scanner is moving
forward. This is to prevent any variation in the scanner motor speed or the exposure
lamp intensity. When the scanner starts moving in reverse, fusing lamp control again
shifts to ON/OFF control.
3. Service Call Conditions
1. Status "52": Thermofuse open or fusing unit improperly installed
The thermofuse will open if the hot roller temperature rises into the 350 ~ 450°C
range (hardware protection).
2. Status "53": Thermistor open
The operation panel CPU checks the conductivity of the thermistor. Code 53 is
displayed if the thermistor is open.
3. Status "54": No warm-up signal
Code 54 is displayed if the hot roller does not reach the ready temperature within
8 minutes after the power is turned on.
4. Status "55": Overheat
The operation panel CPU checks the conductivity of the thermistor.
Code 55 is displayed if the resistance becomes too low.
This occurs if the hot roller temperature is in the 220 ~ 240°C range.
Operation 185°C
Ready 180°C
Energy Saver 175°C
165°C
AC-Line
Fusing Lamp
ON Signal
Zero Cross Signal
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