Hitachi ED-X20EF, Service Manual

Page: 13 / 88

13
ED-X20EF (M1-20ED)
Lamp does not light
What
is the state of
LAMP indicator D303
during operation?
Is the
LAMP installation
correct?
Light
install the Lamp
PWB assembly
MAIN
Is
the voltage
at the (1) of
E804 on the PWB
assembly MAIN fixed
to "L" during
warming-
up?
NG
YES “L”=0V
Change the
lamp. Does lamp
light?
Lamp
Light
YES
NO “H”
Power unit (ballast) Power unit (circuit)
No
What
is the state of
TEMP indicator
D302?
Thermistor
(E1/E2)
Is the
voltage at the (3) of
E804 on the PWB assembly
MAIN set to "L" during
warming-up?
Not light
and blink
PWB assembly MAIN
YES
“L” = 0V
Power unit (ballast)
No
PWB assembly
MAIN
Are
the voltage
supplied to the pin
(2) of connectors** for
DC fans soon after
the button is
pressed?
Observe
the voltage
waveforms at pin (1) of
connectors for DC fans**
soon after the button
is pressed.
Blinks
E1: 5 to 20k Ω
E2: 0.5 to 2k Ω
NG(open/short)
DC fan
(failed in above check)
Correct waveform is drawn below.
f ≥ 40Hz
PWB assembly
MAIN
NO (0V)
PWB assembly
MAIN
Correct
Measure
resistance of
E1 and E2 after
disconnecting them
from MAIN
board.
YES
incorrect
Lights
*: Be sure to unplug the power cord
before measuring resistance.
Not light
**: DC fan connectors are E801,
E802, E806, and E807.
(5V or higher)
OK