52
Phaser 740 and 750 Color Printers
High temperature error
1.
Replace the power supply unit.
2.
Check the fans.
3.
Replace the engine control board.
Low temperature error
1.
Ensure the fuser is properly installed.
2.
Check the fuser’s connection and wiring.
3.
Check to see if the fuser’s thermo-fuse is open. With an ohmmeter, measure the
top two pins of the fuser’s connector. For 110 VAC fuser you should measure 1.6
ohms. For 220 VAC fuser you should measure 5.4 ohms. If it is opened, replace
the fuser.
4.
Replace the fuser.
5.
Replace the power supply unit.
6.
Replace the engine control board.
High voltage error
1.
Replace the high voltage board.
2.
Inspect the high-voltage wiring.
3.
Replace the imaging unit and check the printer for proper operation.
4.
Sequentially replace each toner cartridge and check the printer for proper
operation.
5.
Ensure that excessive conductive grease has not migrated and shorted a high-
voltage contact to ground on the second bias transfer roller.
Thermistor open error
1.
Check the connector CN27 on the engine control board.
2.
Ensure a 110 volt fuser has not been installed in a 220 volt printer; it will damage
the power supply thermistor and require the power supply be replaced.
3.
Replace the fuser.
4.
Replace the engine control board.
Summary of Contents for Phaser 740
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Page 129: ...Service Guide 117 Figure 3 Motor and fan FRUs 3102 37 1 10 9 5 8 7 2 6 4 3 ...
Page 131: ...Service Guide 119 Figure 4 Sensor switch and flag FRUs 3102 40 1 7 2 3 4 8 5 6 ...
Page 135: ...Service Guide 123 Figure 6 Imaging and paper feed component FRUs 3102 39 1 2 3 7 9 4 6 8 5 ...