HP Color LaserJet CM4730 Service Manual - Page 642

Individual component diagnostics From the diagnostics menu, you can run tests to check the status of various components in the MFP. During many of the diagnostic tests, the MFP enters a special diagnostics mode, which allows you to send print jobs and interact with the menus. The MFP stays in this mode until you press Stop and then touch Exit Diagnostics at the top of the Troubleshooting menu. In some cases, the MFP must re-initialize after performing a component-level diagnostic test. LED diagnostics Use the following procedure to help identify the cause of high-level printer problems. These problems are indicated by abnormalities in the printer's power-on sequence. The LED that the procedure refers to is on the formatter. This is a "heartbeat" LED that blinks on and off when the formatter is operating correctly. Use Figure 6-3 Formatter LED on page 623 to locate the formatter LED. 1. Does the LED blink with four fast bursts at power on? If no, then perform the following checks. ● Check the firmware. ● Check the memory. ● Check the formatter. 2. Does the LED blink at a fast, steady rate during memory testing (one blink per 8 MB)? If no, then perform the following checks. ● Check the control panel display for an error code. ● Check the memory. ● Check the formatter. 3. Is the LED off for about eight seconds, while the boot code is decompressing, before the display turns on? If no, then perform the following checks. ● Check the firmware. ● Check the control panel display for correct connections and operation. ● Check the control panel display for an error code. 4. Does the LED blink at a steady rate of one blink per second? If no, then perform the following checks. ● Check the firmware. ● Check the formatter. ● Check the control panel display for an error code. 5. If the control panel display does not illuminate, perform an engine test to check the engine. You must have paper loaded in Tray 2 for the engine test. 622 Chapter 6 Problem solving ENWW