Developer Bias Rap - Xerox 3050 Service Manual

CQ 25 Developer Bias RAP
This RAP is used for background and copy
contrast related problems.
Initial Actions
Ensure that the developer bias
connector, A25 P25, is seated
correctly on the high voltage power
supply (HVPS) and that the developer
bias lead is connected to the
developer bias clip.
Go to
FLAG 1
and check the
developer bias lead for a short circuit
to frame or an open circuit.
Procedure
Set
the meter to measure
+
300
VDC.
Connect the
(-)
to the
GND
test point on the
HVPS.
Plug in and switch on the copier. Cheat the
AC
interlock switch and the upper rear cover
interlock switch. Make
a
copy in the light
input, normal copy mode.
The voltage at the developer bias
clip
goes
from approximately
0 . 0 0
VDC t o
approximately
+
200
VDC while a copy is
being made.
I
The voltage
a t A25 P25
Pin
8
of the High
Voltage Power Supply goes from
+
14.1
VDC
to
+
4.9
VDC while a copy is being
made.
A B C
Switch off the copier. Go to FLAG
2
and check the wiring for an open
circuit.
If there is no open circuit, replace the
Control
PWB (PL 1.4).
The voltage at A25 P25A Pin 12 goes low
while a copy is being made.
I
Switch off the copier. Go to FLAG 3
and check the wiring for an open
circuit.
Make a copy in the Dark Input, normal copy
mode.
The voltage at the developer bias clip goes
from approximately
0 . 0 0
VDC t o
approxtmately
+
300 VDC
while a copy is
being made.
I
Replace the High Voltage Power Supply
and perform the Electrostatic Series (ADJ
9.2).
Go to the Copy Quality RAP that directed you
here and continue troubleshooting the copy
quality problem.
I
If there i s no open circuit, replace the
Control PWB (PL 1.4).
beplace the HVPS PWB
and
perform
the
Electrostatic Series
(ADJ 9.2).
Developer
Bias
Volta~es
Whi l e
Copies Are Being Made
I I
copy Contrast
I
I
Oocument
1 I
I
3DARK 2 DARK 1 DARK NORMAL 1 LIGHT 2 LIGHT 3LlGHT
'nputI I I I I I I I
5193
3050 3-75
CQ
25 Developer Bias
RAP