Xerox 8825 Service Manual

01/02
6-17
8825/8830 Printer
Transfer and Developer Bias Voltages incorrect
General Procedures
Transfer and Developer Bias Voltages incorrect (Tag 19)
PROBLEM
Transfer and developer voltages are set incorrectly.
CAUSE
Late in the program it was determined that the developer bias should be set at -420 VDC and
transfer should be set at .6 ma DC . Inadvertently the change was never cut in on the manu-
facturing line. The current settings can cause intermittent broken black lines or background
bands in the process direction.
SOLUTION
PLEASE MAKE THE FOLLOWING ADJUSTMENT CHANGES TO THE printer ON THE
NEXT SERVICE CALL:
1. ADJUST the Transfer output to “+ 0.6 VDC”
Go to GP 1 HVPS Checkout in this section. Locate the Transfer potentiometer (“TRF I”)
nearest the center of the HVPS (closest to the transfer output transformer module). Care-
fully remove the RTV. Using the 26V return on the HVPS as the common and the “TFR
I” test point, adjust the potentiometer to obtain “+ 0.6 +/- 0.1 VDC” during a print.
Mark appropriate change in manual (Table 1 on page 6-10).
CHANGE the Developer Bias default -
Enter diagnostic mode - Go to . Input diagnostic test code 84. ENTER 1E (E is obtained by
holding down the period(.) button and striking the “4” button). ENTER Message: chain 84;
address 01E is 4E. Using the “Previous Button” scroll down six (6) times or until the display
reads chain 84; address 01E is 48.
ENTER
EXIT
EXAMINE Developer bias output level - Go to GP 1 HVPS Checkout in Section 6 of this
manual; . Using the 26V return on the HVPS as the common and the “DEV V” test point. In
the print mode the output should be “(-) 4.20 +/- 0.05 VDC”. Mark appropriate change in
manual (Table 1 on page 6-10).
Mark off TAG 19 on the TAG matrix
Once these adjustments are made you may see a slight increase in toner consumption. The
benefits of doing these adjustments are:
1. Increase “Cleaning Field” latitude
• Reduced occurrence of background bands in the process direction.
• Reduced occurrence of intermittent broken black lines in the process direction.
2. Provides additional lubrication for the cleaning blade.
CAUTION
The tolerance window for electrostatics on the printer is very narrow. This printer must be set
to specifications using the electrometer to ensure proper performance. If electrostatics are set
incorrectly the printer will exhibit print quality problems, excessive dirt levels, and increased
toner consumption.
REQUIREMENTS FOR FIELD RESOLUTION
• DOCUMENTATION N/A
• TAG 19
• PART NUMBERS N/A
• CUT IN SERIAL NUMBER N/A

Xerox 8825 Specifications

General

Brand	Xerox
Model	8825
Category	Printer
Language	English