Lexmark 522n - C Color Laser Printer Service Manual page 72

4520-xxx
FRU
7 LVPS Fuse F1 - Continues
to blow after LVPS installed
in the printer.
8 LVPS
9 Engine Board
2-44
Service Manual
Action
Replace fuse F1 if necessary. Turn
the LVPS on/off switch off and
connect the AC line cord and turn
the LVPS on.
CAUTION: Before checking fuse F1
turn the LVPS Off and disconnect
the AC line cord. Check fuse F1. If
the fuse is blown, replace the LVPS.
CAUTION: Before making any
measurements on the LVPS output
connector, observe all necessary
safety precautions before applying
AC power. Measure the voltage on
LVPS output connector CN3 (Pin 1,
2, 10, or 11). The voltage measures
+5 V dc. If incorrect, replace the
LVPS.
Turn the printer off and disconnect
all the cables from the engine board.
Check for +5 V dc at the engine
board test point. If incorrect, replace
the FRUs in the following order:
1. Engine board
2. Interconnect board
If correct, turn the printer off and
reconnect one cable at a time until
you find the defective assembly.
Service Tip: A short or low
resistance load that is attached to
the engine board can cause the
LVPS to over-current and shut the
+5 V dc supply down to 0 V dc.