Xerox Phaser 790, Service Manual

Page: 240 / 653

10/00
3-8 Phaser 790/DocuColor 2006
IQ6
Initial Issue Image Quality
IQ6 Blank (or Nearly Blank) Sheet RAP
Initial Actions
• Check the end-of-life counters for the Dry Ink Cartridge and the Copy/Print Cartridge (GP
3). Replace if required.
Procedure
WARNING
HIGH VOLTAGE!
Exercise caution when performing the voltage checks in this procedure.
Remove the Rear Cover. Connect the DVM between frame ground and the C terminal on the
HVPS. Print the Test Page (GP 14). The voltage cycles between 0 VDC and roughly -500
VDC as the print is being made.
Y
N
Check the ROS for debris or dirt blocking the window. Replace the ROS (PL 5.1).
Print the Test Page (GP 14). After the third time that the Rotary Motor indexes, open the Front
Door. Remove the Copy/Print Cartridge. There is a partial toner image on the drum
Y
N
Go to the 009-342 RAP to troubleshoot the Developer bias.
Connect the DVM between the D terminal on the HVPS and frame ground. Access the Digital
Output Test (GP 2). Enter code 0B. Press the Item/Enter button. R80 VDC is mea-
sured.
Y
N
There is less than 1 VDC from J 42 pin 7 on the HVPS to ground.
Y
N
Go to Flag 1. Check for an open circuit. If the wire is OK, replace the MCU PWB.
Go to Flag 3. Check for an open circuit or a short circuit to ground. If the wires are OK,
replace the High Voltage Power Supply (PL 11.1).
Exit the diagnostic mode. Make a print of the Test Page (GP 14). Listen for the sound of the
Rotary Frame moving. Immediately after hearing the 4th indexing of the Rotary Frame, open
the Front Door and remove the Copy/Print Cartridge. Examine the IBT Belt. There is a toner
image of the Test Page on the belt.
Y
N
Check the installation and operation of the BTR 2 Cam Assembly and the Belt Cleaner
(PL 7.1). If these assemblies are OK, remove the IBT Assembly (PL 7.1). Check for dirt or
damage to the BTR 1 and BTR 1 Plate Wire (PL 7.3). Clean, repair, or replace as
required.
WARNING
HIGH VOLTAGE!
Exercise caution when performing the voltage checks in this procedure.
Connect the DVM between the F terminal on the HVPS and frame ground. Access the Digital
Output Test (GP 2). Enter code 0A. Press the Item/Enter button. Roughly -1000 VDC is
measured.
Y
N
There is less than 1 VDC from J 42 pin 10 on the HVPS to ground.
Y N
Go to Flag 4. Check for an open circuit. If the wire is OK, replace the MCU PWB.
Go to Flag 5. Check for an open circuit or a short circuit to ground. If the wire is OK,
replace the High Voltage Power Supply (PL 11.1).
Go to Flag 7. Check for an open circuit. If the wire is OK, examine the BTR 2 Assembly (PL
7.5) and the and the Backup Roll and Contact Roll in the IBT Assembly for damage or contam-
ination. Clean, repair, or replace as required.(PL 7.2).
A
A