Minolta Di450 Service Manual page 455

(9) C0400: Exposure Lamp's failure to turn ON
C0420: Exposure Lamp turning ON at abnormal timing
Exposure Lamp (FL51)
Inverter Board (UN51)
Lamp Flat Cable (PWB-IF)
FL51
C0400, C0420
Step
1 Exposure Lamp has discolored.
2 "NG" is displayed when "Scanning Check" of
"Function (IR)" is run.
3 Power Supply Board operation: the voltage
across PJ9C-4 on Power Supply Board and
GND is DC24V after the malfunction has been
reset.
Relevant Electrical Parts
Image Processing Board (PWB-B)
Power Supply Board (PWB-C)
SCP Board (PWB-IC)
UN51
CN2UN51-1
PWB-IF
CN2UN51-2
PJ1IF-4
CN1UN51-1
PJ1IF-3
CN1UN51-2
PJ1IF-2
CN1UN51-3
F1
PJ1IF-1
PJ2IF-4(ON-OFF)
PJ2IF-3(DC24V)
PJ2IF-2(GND)
PJ2IF-1(GND)
Check
T-47
PWB-B
PJ5B-1(ON-OFF)
PJ301B-14(GND)
PJ301B-15(DC24V)
PWB-C
PJ9C-3(GND)
PJ9C-4(DC24V)
PWB-IC
PJ1IC-3(DC24V)
PJ1IC-4(GND)
4002C26TAA
Result Action
YES Change Exposure Lamp.
YES Check the optical path.
Change Image Process-
ing Board or CCD Board.
YES Check and change, as
necessary, flat cable.
Change Inverter Board or
Image Processing Board.
NO Change Power Supply
Board.