Lexmark X500N, Service Manual

Page: 73 / 244

Diagnostic information
2-35
7100-XXX
Cover open service check
Step Questions / actions Yes No
1 Turn printer off, and remove right cover.
See
“Right cover removal” on page 4-13 .
Check all interlock switch (top, rear and
front) actuators for proper operation. Are
actuators good?
Go to step 2. Replace appropriate
actuator:
Front cover for front cover
interlock switch. See
“Front cover assembly
removal” on page 4-12
.
Top cover assembly for top
cover interlock switch. See
“Top cover assembly
removal” on page 4-10
.
Rear cover actuator for rear
cover interlock switch.
Actuator is contained in
parts packet.
2 Check each interlock switch (top, rear and
front) for proper operation and damage.
Listen for switching action. Using an
ohmmeter, check switches. When switch is
open (cover open), resistance between pin
1 and pin 3 is 0 and pin 1 and 2 is infinite.
Closing switch will show 0 resistance
between pins 1 and 2 and infinite resistance
between pins 1 and 3. Are switches good? Go to step 3. Replace switch in question.
See
“Front door interlock
switch with bracket” on
page 4-21
for front interlock
switch, see “Power supply
fan removal” on
page 4-48
for rear and top
interlock switches.
3 Turn printer on. Check for 5 VDC between
front cover interlock switch pin 1 (top pin)
and ground. Is 5 VDC present? Go to step 5. Go to step 4.
4 Turn printer off, and check cable for
continuity between LVPS ACN2 pin 1 and
cable that connects to front cover interlock
switch pin 1. Is cable okay? Replace LVPS. See “Low
voltage power supply
(LVPS) with cage
removal” on page 4-40
.
Replace cable.
5 Check the following cables for continuity:
• Engine controller board MCN4 pin 1 to
rear interlock switch pin 3
• Engine controller board MCN4 pin 3 to
top interlock switch pin 3
• Top cover interlock switch pin 1 to front
cover interlock switch pin 2
• Top cover interlock switch pin 2 to rear
cover interlock switch pin 1
• LVPS ACN2 pin 2 to rear cover interlock
switch pin 2.
Are any cables defective?
Replace cable. Replace engine controller
board. See
“Engine
controller board removal”
on page 4-34
.