Test pages
Printing test pages helps you determine whether or not the printer engine and the formatter are functioning.

Engine-test page
To verify that the printer engine (all printer components except the formatter, formatter DIMMs, EIO products, and the stacker or stapler/stacker) is functioning, print an engine-test page. Use a small, non-metallic, pointed object to depress the test-page switch, which is located on the right side of the printer (callout 1).

The test page should have a series of vertical lines. The test page prints from the last tray that you printed from. However, if the printer has been turned off and then on again since the most recent print job, the page will print from tray 2. The printer will continuously print test pages as long as the test-page switch is depressed. The printer will not print a test page if it is in PowerSave or Sleep mode.

NOTE A damaged formatter might interfere with the engine test. If the engine-test page does not print, try removing the formatter and 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.

Formatter test page
To verify that the formatter is functioning, print a configuration.
1 Press ( SELECT button) or the MENU button to open the menus.
2 Press ( DOWN ARROW button) to scroll to INFORMATION.
3 Press to select INFORMATION.
4 Press to scroll to PRINT CONFIGURATION.
5 Press to select PRINT CONFIGURATION.

Paper-path test
This test generates one or more test pages that can be used to isolate the cause of jams.

To isolate a jam, you can specify which input tray to use, which output bin to use, whether to use the duplex path, and the number of pages to print. Printing multiple pages helps to isolate intermittent
jam problems. The following options are available for this test.
■ Print test page. This option uses factory default settings to run the paper path test. The page starts from tray 2, does not use the duplex path, and prints a single page. The user can specify the number of pages to be printed.
■ Source. Use this option to select tray 1, tray 2, or tray X (if optional tray feeders are installed) as the page source.
■ Destination. Use this option to send the test page to the optional stacker or stapler/stacker if this accessory is installed.
■ Duplex. Use this option to send the test page through the duplex path.
■ Page count. Use this option to sets the number of test page copies to be printed. The choices are 1, 10, 50, 100, and 500.

To perform a paper-path test
1 Press ( SELECT button) or the MENU button to open the menus.
2 Use ( UP ARROW button) or (DOWN ARROW button) to scroll to DIAGNOSTICS, and then press <Check mark>.
3 Use <Up Arrow or (Down Arrow) to scroll to PAPER PATH TEST, and then press . <Check Mark>
4 Use <up Arrow> or<Down Arrow> to scroll through the available test options, and then press .
5 After the test options are selected, use or to scroll to PRINT TEST PAGE, and then press to start the test.

NOTE To test the stacker and stacker/stapler paper path, see Stacker paper-path test and Stapler/stacker paper-path test.

Half self-test functional check
The electrophotographic process can be subdivided into the following stages:
■ Cleaning (removes excess toner from the drum surface)
■ Conditioning (places a uniform electrical charge on the drum)
■ Writing (the laser strikes the surface of the drum to create an electrostatic image)
■ Developing (forms the toner image on the drum)
■ Transferring (charges transfer the image to the print media)
■ Fusing (heat and pressure produces a permanent image)

The purpose of the half self-test check is to determine which process is malfunctioning. Use this procedure to perform the test:
1 Print a configuration page from the control panel INFORMATION menu.
2 Open the top cover after the paper advances half-way through the printer (about 3 to 5 seconds after the main motor begins rotation). The leading edge of the paper should have advanced past the print cartridge.
3 Remove the print cartridge.
4 Open the print cartridge drum shield to view the drum surface.
If a dark and distinct toner image is present on the drum surface, assume that the first four functions of the electrophotographic process are functioning (cleaning, conditioning, writing, and developing), and troubleshoot the failure as a transfer or fusing problem. If no image is present on the photosensitive drum, perform the following check.

Drum-rotation functional check
The photosensitive drum, located in the print cartridge, must rotate in order for the print process to work. The photosensitive drum receives its drive from the main gear assembly. Use this procedure to determine whether the drum is rotating:
1 Open the top cover.
2 Remove the print cartridge.
3 Mark the cartridge drive gear with a felt-tipped marker. Note the position of the mark.
4 Install the print cartridge and close the top cover. The start-up sequence should rotate the drum enough to move the mark on the gear.
5 Open the printer and inspect the gear that was marked in step 3. Verify that the mark moved. If the mark did not move, inspect the main gear assembly to make sure that it meshes with the print-cartridge gears. If the drive gears function but the drum does not move, replace the print cartridge.

NOTE This test is especially important if refilled print cartridges are in use.

Printer resets and power-on modes
The following sections describe the types of printer resets and power-on modes.

Cold reset
A cold reset unlocks menus that have been previously locked and returns all of the control panel menu items (including EIO settings) to the factory defaults. However, it does not clear the values in the service menu (such as the serial number and page counts).

NOTE Before performing a cold reset, print a menu map and a configuration page (see Menu map and Configuration page). Use the information on the configuration page to reset any customer-set printer configuration values that the cold reset procedure changes.

To perform a cold reset
1 Turn the printer power off.
2 For HP Laserjet 4200/4300 Series printers: Hold down ( SELECT button), and then turn the printer power on.
For HP Laserjet 4250/4350 Series printers: Turn the printer power on, and then hold down (SELECT button) when the memory count begins.
3 Continue holding down until all three printer control-panel lights flash once and then remain on. This might take up to 10 seconds.
4 After the message SELECT LANGUAGE appears on the display, press (UP ARROW button) or (DOWN ARROW button) until COLD RESET is highlighted.
5 Press . The printer performs a cold reset and then continues its power-on sequence.
6 Check all I/O settings and reset any customer-set printer configuration values.

NVRAM initialization
CAUTION Initializing the NVRAM resets the serial number, the event log, the page counts, the EIO card, and the embedded print server. Initializing the NVRAM also resets service-menu values to factory defaults. Use the service menu to restore the serial number and page counts. Also reconfigure any computers that print to this printer so that the computers can recognize the printer. Initialize the NVRAM only when absolutely necessary. In most situations, use a cold reset rather than a NVRAM initialization to reset printer settings (this will retain the values in the service menu).

NOTE Before performing a NVRAM initialization, print a menu map and a configuration page (see Menu map and Configuration page). Use the information on the configuration page to reset any customer-set printer configuration values that the NVRAM initialization procedure changes. Make note of the total page count, maintenance count, and the serial number.

To initialize NVRAM
1 Turn the printer power off.
2 Remove any installed accessories (for example, a stapler/stacker).
3 For HP Laserjet 4200/4300 Series printers: Hold down ( SELECT button), and then turn the printer power on.
For HP Laserjet 4250/4350 Series printers: Turn the printer power on, and then hold down (SELECT button) when the memory count begins.
4 Continue holding down until all three printer control-panel lights flash once and then remain on. This might take up to 10 seconds.
5 Press ( UP ARROW button).
6 Press the PAUSE/RESUME button (LJ 4200/4300) or the MENU button (LJ 4250/4350). The display should show SKIP DISK LOAD.
7 Press until NVRAM INIT is highlighted.
8 Press . The printer initializes NVRAM and then continues its power-on sequence.

Hard-disk initialization
CAUTION A hard-disk initialization erases and reformats the printer hard disk. Perform a hard-disk initialization only if an error code on the control panel indicates an EIO disk error. Always try initializing the hard disk before replacing it.

NOTE Before performing a hard-disk initialization, print a menu map and a configuration page (see Menu map and Configuration page). Use the information on the configuration page to reset any customer-set printer configuration values that the hard-disk initialization procedure changes.

To initialize the hard disk
1 Turn the printer power off.
2 For HP Laserjet 4200/4300 Series printers: Hold down the PAUSE/RESUME button, and then turn the printer power on.
For HP Laserjet 4250/4350 Series printers: Turn the printer power on, and then hold down the MENU button when the memory count begins. 3 Continue holding down the button until all three printer control-panel lights flash once and then remain on. This might take up to 10 seconds.
4 Press ( BACK ARROW button). The display should show INITIALIZE DISK.
5 Press . The printer initializes the hard disk and continues its power-on sequence.

Associated printer models:
HP Laserjet 4200
HP Laserjet 4240
HP Laserjet 4250
HP Laserjet 4300
HP Laserjet 4350
HP Laserjet 4345MFP