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9-2
CI005 and CI006 are capacitors to stabilize the fluores-
cent lamp discharging current. After the discharging
starts, CI005 and CI006 limit the flow of the current
with the reactance (X
C
= 1/wc) of CI005 and CI006.
Before the fluorescent lamp turns on, the collector
pulse of QI007 is 70 – 80 V(p-p). The voltage is
stepped up to 420 – 480 V(p-p) by LI002 and applied to
the fluorescent lamp. When a filament is warmed, the
discharging starts and the collector voltage of QI003
becomes approx. 30 V(p-p). The fluorescent tube
voltage at turning on is approx. 120 V(p-p).
ARM SW works as a ON/OFF switch for the camera
power supply. When ARM SW turns on, the power is
supplied to the camera.
The waveforms of each section at operation is shown in
Figs. 9-1-3 and 9-1-4.
Fig. 9-1-3
Fig. 9-1-4
9-2. Troubleshooting
9-2-1. Fluorescent does not turn on
Fig. 9-2-1
31V
0
0
1.5A
QI003
Collector
voltage
Collector
current
70 kHz
+30V
– 80V
0V
– 0.22A
+0.16A
0
Fluorescent
lamp
voltage
Fluorescent
lamp
current
70 kHz
OK
OK
NO
NG
YES
NO
YES
Replace
fluorescent lamp.
Fluorescent lamp
does not turn on.
12V : between pins
5 and 7 of PM01.
QI002 base.
Pulse higher than
25 V(p-p) is developed at
QI003 collector.
Higher than 10V.
Check fluorescent
lamp ON/OFF SW
(SM005)
and ARM SW.
Lower than 3V.
Check secondary
side of LI002.
Check power
supply unit.
Check primary
side of LI002.