Brother HL-4000CN Service Manual page 225

Step
Checking drive PWB for signal
Print 1 sheet.
13
Is P/J42-29PIN<=>P/J42-14PIN
+3.3VDC?
Checking MCU and HVPS PWB for signal
14
Print 1 sheet.
Is P/J12-2PIN<=>P/J12-17PIN +3.3VDC?
Checking fuser fan
Does fuser fan function normally?
15
Using fuser fan diagnostic tool, check by
digital output test.
Checking drive PWB for signal
16
Print 1 sheet.
Is P/J50-7PIN<=>P/J50-9PIN +24VDC?
Checking drive PWB for signal
17
Print 1 sheet.
Is P/J42-30PIN<=>P/J42-14PIN 0VDC?
Checking MCU and HVPS PWB for signal
18
Print 1 sheet.
Is P/J12-1PIN<=>P/J12-17PIN 0VDC?
Checking harness ASSY DUP for
19
continuity
Is J50<=>J137 continuous normally?
Checking fuser fan
20
Check if an error occurs though the fuser
fan was replaced with a new one.
Checking drive PWB for signal
21
Print 1 sheet.
Is P/J50-8PIN<=>P/J50-9PIN +3.3VDC?
Checking drive PWB for signal
Print 1 sheet.
22
Is P/J42-27PIN<=>P/J42-14PIN
+3.3VDC?
Checking MCU and HVPS PWB for signal
23
Print 1 sheet.
Is P/J12-4PIN<=>P/J12-17PIN +3.3VDC?
Check
V-15
Remedy
Yes
Replace drive
Go to step [14]
PWB
Replace MCU
Replace harness
and HVPS
ASSY DRV2
PWB
Replace MCU
Go to step [16]
and HVPS PWB
Go to step [19] Go to step [17]
Replace drive
Go to step [18]
PWB
Replace
Replace MCU and
harness ASSY
HVPS PWB
DRV2
Replace
Go to step [20] harness ASSY
DUP
Replace Go to
End of work
step [21]
Fuser fan Go to step [22]
Replace drive
Go to step [23]
PWB
Replace MCU
Replace harness
and HVPS
ASSY DRV2
PWB
No