HP LaserJet Enterprise 500 Service Manual - Page 283

Formatter to control panel communication interruptions ● The firmware does not fully initialize and configure the control panel interface. ● The control panel is not functioning (either a failed component or power problem). ● Interface cabling between the formatter and control panel is damaged or disconnected. TIP: If the heartbeat LED is illuminated-by an error condition or normal operation-the formatter is fully seated and the power is on. The pins for the LED circuit in the formatter connector are recessed so that this LED will not illuminate unless the formatter is fully seated. The heartbeat LED operates according to the product state. When the product is initializing, see Heartbeat LED, product initialization on page 247. When the product is in Ready mode, see Connectivity LED, product operating on page 249. Heartbeat LED, product initialization The following table describes the heartbeat LED operation while the product is executing the firmware boot process. NOTE: When the initialization process completes the heartbeat LED should be illuminated solid green -the LED is off if the product is in Sleep mode. If after initialization the heartbeat LED is not solid green, see Connectivity LED, product operating on page 249. Table 3-2 Heartbeat LED, product initialization Product initializing state Heartbeat LED, normal state Heartbeat LED, error state No power (power cord unplugged or power switch off) Power on (immediately after the power switch pressed) Off Red, solid ● Duration should be 1 second or less Serial peripheral interface (SPI) flash memory boot Green, solid Not applicable Red, solid ● Firmware error; problem finding hardware and booting the serial peripheral interface flash memory ◦ Boot process halted Replace the formatter. Red, solid ● Firmware error; problem corrupt or missing SPI flash memory ◦ Boot process halted Replace the formatter. ENWW Tools for troubleshooting 247