HP Color LaserJet CM4730 Service Manual - Page 536
Power-on checks, Make sure that the power switch is in
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Power-on checks The basic MFP functions should start up as soon as the MFP is plugged into an electrical outlet and the power switch is pushed to the on position. If the MFP does not start, use the information in this section to isolate and solve the problem. First, turn on the MFP power. If the control-panel display remains blank, random patterns appear, or asterisks remain on the display, perform power-on checks to locate the cause of the problem. During normal operation, the main cooling fan begins to spin briefly after the MFP power is turned on. Place your hand over the holes in the rear cover, above the formatter. If the fan is operating, you will feel a slight vibration and feel air passing into the MFP. You can also lean close to the MFP and hear the fan operating. When this fan is operational, the DC side of the power supply is functioning correctly. After the fan is operating, the main motor turns on (unless the top cover is open, a jam condition is sensed, or the paper-path sensors are damaged). You should be able to visually and audibly determine if the main motor is turned on. If the fan and main motor are operating correctly, the next troubleshooting step is to isolate print engine, formatter, and control panel problems. Perform an engine test (see Engine test on page 617). If the formatter is damaged, it might interfere with the engine test. If the engine test page does not print, try removing the formatter and then performing the engine test again. If the engine test is then successful, the problem is almost certainly with the formatter, the control panel, or the cable that connects them. If the control panel is blank when you turn on the MFP, check the following items. 1. Make sure that the MFP is plugged into an active electrical outlet that delivers the correct voltage. 2. Make sure that the power switch is in the on position. 3. Make sure that the fan runs briefly, which indicates that the power supply is operational. 4. Make sure that the formatter is seated properly. 5. Make sure that the control panel display wire harness is connected. See Control panel on page 267. 6. Make sure that the firmware flash memory card and the formatter are seated and operating correctly. See Flash memory card (firmware) on page 306. 7. Remove any HP Jetdirect or other EIO cards, and then try to turn the MFP on again. NOTE: If the control panel display is blank, but the main cooling fan runs briefly after the MFP power is turned on, try printing an engine test page to determine whether the problem is with the control panel display, formatter, or other MFP components. See Engine test on page 617. 516 Chapter 6 Problem solving ENWW