Lexmark W820 Service Manual page 122

Error Code 929
A CRU memory communication error occurred.
Logic Control on the MCU PWB could not access CRU Memory data.
Step Actions and Questions
1 LVPS +5VDC CHECK
Measure the voltage between J400-1 and FG, and between
J400-2 and FG on the MCU PWB.
Is there +5VDC between J400-1 and FG, and +5VDC
between J400-2 and FG?
2 CRU REPLACEMENT
Replace the EP Cartridge with a different one.
Does the error code still appear?
3 MCU PWB REPLACEMENT
Replace the
Does the error code appear?
4 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 listed below, one at a time, until
you isolate and solve the problem.
• Wiring and connectors linking the FRUs
• I/O PWB - Go to
2-26
Service Manual
"Engine Board (MCU PWB)" on page
"I/O PWB" on page
4025-XXX
4-92.
4-89.
Yes No
Go to step 2 Go to the
"Printer
Wiring
Diagrams"
on page 5-14
to
troubleshoot a
loss of +5VDC
Go to step 3 Problem
solved
Go to step 4 Problem
solved