Canon IR5000 - iR B/W Laser, Service Handbook

Page: 67 / 252

CHAPTER 2 STANDARDS AND ADJUSTMENTS
2-47
8. Checking the Surface Potential Control System
8.1 Outline
In the event of an image fault, it is important to find out if the cause is within the static
latent image formation block (including the photosensitive drum and the potential control
system) or is with the developing/transfer mechanism; and to isolate the cause, the surface
potential must first be checked in service mode.
8.2 Disabling the Auto Control Mechanism
The potential control system may be checked by disabling the auto control mechanism
(referred to hereafter as “non-auto control mode).
If improvements are noted in the images made in non-auto control mode, the potential
measurement unit and the DC controller PCB may be suspected.
Further, non-auto control mode may also be made use of as an emergency measure
against an error in the auto control mechanism.
In non-auto control mode, all control settings (corona current, intensity, de-
veloping bias) will automatically be set to the standard settings stored in the
ROM.
Starting Non-Auto Control Mode
1) Make the following selections in service mode, and enter ‘0’:
COPIER>OPTION>BODY>PO-CNT; then, press the OK key.
2) Press the Reset key twice.