HP LaserJet 4 Service Manual - Page 263

57 (or 57.1) SERVICE Message (Main Motor Failure) The 57 SERVICE indicates that the DC Controller PCA detected a general motor failure. The Main Motor drives all moving components in the printing process. The Main Motor is a 4-phase, DC servo motor controlled by the DC Controller PCA. The formatter detects a Main Motor failure when: • The Main Motor does not come up to speed within one second of receiving drive voltage. • The Main Motor deviates from the correct speed for one second after reaching the correct speed. Main Motor Functional Checks • Inspect the gear train for debris that would block the free operation of the gears. • Check the gears in the Toner Cartridge for wear and binding. • Reseat J211 (or J214 on the HP LaserJet 4 Plus/4M Plus) on the DC Controller PCA, and the main connector on the Main Motor Assembly. Refer to Figures 7-16 and 7-17 for the DC Controller PCA connector locations. • If the problem persists, check that the +24B Voltage is present on the DC Controller. If the voltage is not present, replace the DC Controller. If the voltage is present, and the motor does not rotate, replace the Main Motor Assembly (see Figure 7-11 for location). Troubleshooting 7-33