Lexmark W820 Service Manual page 113

Step Actions and Questions
6 MAILBOX VOLTAGE CHECK
Remove the Rear Cover.
Switch on the printer power.
Measure the voltage between J800-8 and FG (frame ground),
the voltage between J800-10 and FG, and the voltage between
J800-12 and FG on the Mailbox Control PWB.
Is there +24VDC between J800-8 and FG, +5VDC between
J800-10 and FG, and +5VDC between J800-12 and FG on
the Mailbox Control PWB?
7 MCU PWB POWER OUT CHECK
Remove the printer Rear Cover.
Measure the voltage between J404-6 and FG, and the voltage
between J404-12 and FG on the MCU PWB.
Is there +5VDC between J404-6 and FG, and is there
+24VDC between J404-12 and FG?
8 MCU PWB REPLACEMENT
Replace the printer Engine Board (MCU PWB). Go to the
printer service manual for the Removal and Replacement
Procedure.
Does the Mailbox function normally?
9 The following printer FRUs and areas are associated with this
specific problem. One or more of these FRUs or areas may
have failed partially or completely. If you cannot isolate this
problem using the steps in this service check, replace each
FRU or troubleshoot each area, one at a time, until you isolate
and solve the problem.
• Wiring and connectors linking the FRUs
4025 Options
Yes No
Replace the Go to step 7
"Mailbox
Control
PWB" on
page 4-44
Go to step 8 Use the Block
Diagrams in
the printer
service
manual to
troubleshoot a
loss of DC
voltage
Problem Go to step 9
solved
Diagnostic Information
2-31