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5

Service Calibrations and Adjustments

HP DesignJet 430, 450C and 455CA Printers

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Calibrations
The only Calibration that the Printer requires is the Accuracy Calibration which must be performed under certain conditions. Accuracy Calibration Purpose The accuracy calibration (X axis calibration) procedure is used to correct the end point accuracy of the media axis. The carriage axis does not require calibration and is used to calibrate the media axis. The accuracy calibration also includes calibration of the optical line sensor on the carriage. The accuracy calibration is also used to correct the error of the X axis movement to avoid banding. Perform the accuracy calibration whenever the:
D D D D D D D D

EEROM is erased. Electronics module is replaced. Drive roller is removed or replaced. Media (X axis) motor is removed or replaced. Drive roller gear is removed or replaced. Cartridge carriage is replaced. Mark encoder is removed or replaced. Optical sensor is removed or replaced.

What is the End Point Accuracy Specification ? The end point accuracy specifies how accurately a Printer can draw a given length of line. The end point accuracy specification for the Printers is 0.38 mm (0.015 in) or 0.2% of the specified vector length, whichever is greater, at 23dC (73dF), at 50 60% relative humidity on HP matte film. Use the following formula to calculate the Printer's accuracy:
Measured length Desired length Desired length x 100 = %Error

What can Affect the End Point Accuracy ? Various part tolerances inside the Printer affect the accuracy (in particular the drive roller). Other outside influences include: Media thickness. Thicker media creates longer lines. D Media expansion. As the media grows, so do the lines. D The application software may be instructing the Printer to draw an incorrect line length. D The EEROM has been cleared. The accuracy constants are stored in this non volatile memory component.
D

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HP DesignJet 430, 450C and 455CA Printers

Service Calibrations

Before Performing the Accuracy Calibration 1 Under normal environmental conditions and on HP Matte Film D/A1 size media, plot a drawing that contains two X" marks nominally positioned 500 mm (19.69 in.) apart. 2 Measure the distance between the centers of the X" marks on the plot. Accuracy calibration is needed if this distance is not 500 mm (19.69 in) 1 mm (0.04 in). If the measured accuracy, media thickness, or environmental conditions vary greatly from the factory standards, recalibrate the Printer by continuing with the following procedure. Performing the Accuracy Calibration 1 Place a sheet of HP Matte Film over the top of the Printer for 10 minutes to let the sheet stabilize to the environmental conditions. Use a sheet of approximate size A1 or D. You must use HP Matte Film. Otherwise the optical sensor on the carriage will be calibrated incorrectly, and the Printer will have problems loading some types of media. 2 Enter into Service Mode 2, by powering ON the Printer while holding down the Media Source key. 3 Set the Media Type on the front panel to Coated Paper. 4 Load the film, with the matte (dull) side down, in portrait orientation into the Printer. 5 When the Ready LED lights up, press Reprint key. The Ready LED begins to flash and the Printer takes several minutes to plot the calibration plot (see Figure 1). The Printer ejects the sheet, and the Load Media LED lights up. 6 Unload the sheet. 7 Wait until the ink on the sheet is dry. 8 Cut the sheet along the dotted line and reload the sheet facedown into the Printer, in the direction indicated by the arrows on the calibration plot (see Figure 2). The Ready LED begins to flash. The Printer takes less than 10 minutes to: read the calibration sheet; calculate the calibration data; save the data in the EEROM; and eject the sheet. 9 Unload the sheet.

Service Calibrations

HP DesignJet 430, 450C and 455CA Printers

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Figure 1

Figure 2

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HP DesignJet 430, 450C and 455CA Printers

Service Calibrations

Adjusting the Carriage to Media Distance
It is very important that the distance between the carriage and the media is within certain limits. If the distance between the cartridge nozzles and the media is too small, ink smears on the media. If the distance is too big, unwanted spray appears around the ink dots, and vertical lines are not straight. (A big distance may also prevent the carriage from actuating the bail lever.) Whenever you remove the Drive Roller or the Cartridge Carriage, take care to reinstall them correctly. Incorrect installation may result in the carriage being too close or too far from the media. For the correct installation procedure ' Chapter 8. To check the carriage to media distance A Gauge (included with the carriage assembly) has been produced to check the carriage to media distance to make sure it is within the tolerances allowed. Use this gauge to check the carriage to media distance as follows: 1 Open the top cover. 2 Move the carriage out of the service station.

3 Remove the Yellow cartridge from the carriage. 4 Check the gauge to determine the GO and NO GO sides:
NO GO GO

5 Place the gauge on the drive roller on the left hand side of the carriage, with the GO side facing the carriage, in the position shown below:

Service Calibrations

HP DesignJet 430, 450C and 455CA Printers

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Gauge Y B Gauge must be parallel to the center line of the Drive Roller

Drive Roller

6 With the gauge held in place, manually move the carriage over the GO side of the gauge. The ledge, indicated below, should easily pass over the GO side of the gauge.
WARNING
Make sure that the carriage is in the down position at all times when passing over the gauge.

Ledge

If the ledge does not go over the GO side of the gauge, adjust the carriage to media distance ' page 5 7. 7 Remove the gauge and replace it on the drive roller with the NO GO side facing the carriage. 8 With the gauge held in place, manually try to pass the carriage over the NO GO side of the gauge. The ledge, indicated above, should NOT pass over the NO GO side of the gauge. If the ledge does go over the NO GO side of the gauge, adjust the carriage to media distance ' page 5 7. 9 Replace the Yellow cartridge in the carriage. 10 Move the carriage back into the service station. 11 Close the top cover.

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HP DesignJet 430, 450C and 455CA Printers

Service Calibrations

To adjust the carriage to media distance You will need to adjust the carriage to media distance if: The ledge on the carriage did not pass over the GO side of the gauge. This means that the carriage is positioned too close to the drive roller. D The ledge on the carriage did pass over the NO GO side of the gauge. This means that the carriage is positioned too far from the drive roller.
D

Adjust the carriage to media distance as follows: 1 Release the two indicated clips on the top of the cartridge carriage by pulling them slightly outwards.

Take care neither to cut yourself on the encoder strip, nor to damage the strip.

2 Pull the top of the carriage up.

Service Calibrations

HP DesignJet 430, 450C and 455CA Printers

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3 Tighten or loosen the indicated screw on the carriage. This will adjust the carriage angle on the slider rod, thus increasing or decreasing the carriage to media distance.

Torx-8

Rotating Clockwise

Gap Increases

4 Check the carriage to media distance ' page 5 5. 5 Reinstall the top of the carriage. 6 Check the trailing cable to make sure that it is positioned under the plastic tabs at the back of the carriage cover, and not above them.

Trailing cable under tabs !

Otherwise, the Printer will not be able to load media.

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HP DesignJet 430, 450C and 455CA Printers


Service Calibrations