Ricoh SP 8400DN Field Service Manual page 1291

SC No. Type
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SC No. Type
SC574- A Pressure Roller Thermistor (End) High Temperature Detection (hardware)
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In the event of an error
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Error Name/Error Condition/Major Cause/Solution
Pressure roller thermistor (end) defective
Fusing controller software defective
Check the fusing unit.
Check that the triac of the AC controller on the PSU does not short-circuit.
Reconnect the following connectors: CN115 of BCU, connectors between the fusing
unit and the BCU, connectors connected to the fusing unit
Replace the following harness: CN115 of BCU, connectors between the fusing unit and
the BCU, connectors connected to the fusing unit
Replace the BCU.
Replace the fusing unit.
Error Name/Error Condition/Major Cause/Solution
Triac short-circuit
Engine controller defective
Pressure roller thermistor (end) defective
Fusing control: out of control
Check the sensor temperature with the following SPs. If the temperature is lower than
250°C, replace the thermopile or thermistor.
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SP1-141-101 (Thermopile (center))
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SP1-141-102 (Thermopile (edge))
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SP1-141-103 (Thermistor (center))
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SP1-141-104 (Thermistor (edge))
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SP1-141-151 (Thermopile (center): 200 msec before the SC is generated)
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SP1-141-152 (Thermopile (edge): 200 msec before the SC is generated)
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SP1-141-153 (Thermistor (center): 200 msec before the SC is generated)
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SP1-141-154 (Thermistor (edge): 200 msec before the SC is generated)
Note: The high temperature state of the fusing unit is detected when the temperature
detected by the sensor is 250°C or more. Therefore, if the temperature of the above SPs
is lower than 250°C, the thermopile or thermistor may be defective or out of position.
Check the fusing unit.
Check that the triac of the AC controller on the PSU does not short-circuit.
Replace the PSU.
Reconnect the following connectors: CN115 of BCU, connectors between the fusing
unit and the BCU, connectors connected to the fusing unit
Replace the following harness: CN115 of BCU, connectors between the fusing unit and
the BCU, connectors connected to the fusing unit
6.Troubleshooting
553