Xerox N2125N - DocuPrint B/W Laser Printer Service Manual page 45

RAP 25 Malfunctioning LCD/LED
There is an erratic display on LCD/LED.
Procedure
Switch the printer power off. Remove any options connected to the System Controller PWB.
Disconnect P/J18 from the System Controller PWB. Switch the printer power on. On the Sys-
tem Controller PWB, check the following voltages between P/J18 and frame ground.
With P/J18
P18 Disconnected
Pin 1 3.3VDC
Pin 2 0.0VDC
Pin 3 1.4VDC
Pin 4 0.0VDC
Pin 5 3.3VDC
Pin 6 1.4VDC
Pin 7 3.3VDC
Pin 8 0.0VDC
All the voltages listed in the column "with P/J18 disconnected" are correct.
Y N
On the System Controller PWB, check the voltage on P/J13 between pins 1 and 2. The
voltage is 3.3VDC.
Y N
Switch the printer power off. Disconnect P/J13 from the System Controller PWB.
Switch the printer power on. Check the voltage between pins 1 and 2 on the discon-
nected plug. The voltage is 3.3VDC.
Y N
On the LVPS, check the voltage on P/J282 between pins 1 and 2. The voltage
is 3.3VDC.
Y N
Replace the LVPS (REP
Repair or replace the harness between the LVPS and the System Controller
PWB (PL 10.1).
Replace the System Controller PWB
On the System Controller PWB, check the voltage on P/J13 between pins 3 and 4. The
voltage is 5.0VDC.
Y N
Switch the printer power off. Disconnect P/J13 from the System Controller PWB.
Switch the printer power on. Check the voltage between pins 3 and 4 on the discon-
nected plug. The voltage is 5.0VDC.
Y N
On the LVPS, check the voltage between P/J PN1 pins 1 and 2. The voltage is
24.0VDC.
A B C
Status Indicator Repair Analysis Procedures
RAP 25
Table 1
With P/J18
Connected
3.3VDC
0.0VDC
3.3VDC
0.0VDC
3.3VDC
3.3VDC
3.3VDC
3.3VDC
9.5).
(REP 9.2).
A B C
Y N
Replace the LVPS
Replace the System Controller +5.0VDC Power Supply
Replace the System Controller PWB
Switch the printer power off. Reconnect P/J18 to the System Controller PWB. Switch the
printer power on. Check the voltages between the pins listed in Table 1 and frame
ground. All the voltages listed in the column "with P/J18 connected" are correct.
Y N
Replace the Control Panel Assembly
Switch the printer power off. Reinstall the removed options one at a time, switching on the
power and checking the voltages between the pins listed in Table 1 and frame ground
after each component is installed. Replace the option just installed if the voltage fails.
After all the options are reinstalled, the LCD display is still erratic.
Y N
Problem solved. Return to
Replace the Control Panel Assembly
Controller PWB (REP 9.2).
Switch the printer power off. Reconnect P/J18 to the System Controller PWB. Switch the
printer power on. Check the voltages between the pins listed in Table 1 and frame ground. All
the voltages listed in the column "with P/J18 connected" are correct.
Y N
Replace the Control Panel Assembly
Switch the printer power off. Reinstall the removed options one at a time, switching on the
power and checking the voltages between the pins listed in Table 1 and frame ground after
each component is installed. Replace the option just installed if the voltage fails. After all the
options are reinstalled, the LCD display is still erratic.
Y N
Problem solved. Return to Initial Actions
Replace the Control Panel Assembly
troller PWB (REP 9.2).
02/2000
2-28
(REP 9.5).
(REP 9.4).
(REP 9.2).
(PL 1.1).
Initial Actions and restart.
(PL 1.1). If the problem persists, replace the System
(PL 1.1).
and restart.
(PL 1.1). If the problem persists, replace the System Con-
DocuPrint N2125
Initial Issue