F. Electrical System1. When Replacing the DC Controller PCB1) Install the new DC controller PCB.2) Press the service mode switch with a clip over the cover.3) Select the following in service mode ( ):‘RAM_INIT’:0 ← (]: START)4) Press the user mode key ].5) Execute AE adjustment.6) Enter the values indicated on the label attached behind the front door.7) Enter the settings suited to the user in service mode ( ).8) Press the Reset key twice.2. Checking the Surface Potential Control Systema. OutlineIf an image fault occurs, try to find out whether the problem is in the latent imageformation block (including the photosensitive drum and the potential control system) orthe developing/transfer system, requiring a check on the surface potential. (You maycheck the surface potential in service mode.)b. Disabling the Auto Control MechanismYou may disable the auto control mechanism to find out whether the corona currentcontrol, lamp intensity control, or developing bias control is faulty or not (non-auto controlmode).Further, as a temporary remedy, you may use non-auto control mode against a faultin the auto control mechanism.In auto control mode, all outputs are set to default settings.q Steps1) Select ‘PO_CONT’ in service mode ( ).2) Check to make sure that the indication on the display is as follows:NIP : 0 ← (] : START)PO_CONT : 0 ← (] : START)Changes to ‘1’.]4]]5]]4]COPYRIGHT © 1997 CANON INC. CANON NP6350/NP6251 REV. 0 JULY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)CHAPTER 11 TROUBLESHOOTING11-42
