PC-UM10M
LL-T1820-H/B TROUBLE SHOOTING
4 – 2
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The port from which the analog signal cable
was removed is the input signal port selected?
48th pin and 49th pins of IC601 are in H level
(DC+3.3V)?
LD618 and LD621 are in H level (about
DC+1.9V)?
LD801 is less than DC+1.0V at maximum
brightness?
1st pin of CN2, CN3, CN4, CN5, CN6, and CN7
on inverter PWB unit is about 750 Vrms? (Use
caution not to get electric shock accident. Use
a high-voltage probe (more than 100:1) for
measuring voltage.)
Check analog signal cable and CN100
(CN200).
Check SDA and SCL signals and circuits
around IC401 and IC601.
Press INPUT key to switch over to the
correct input signal port.
Check the power unit and cable and their
connections, and DC+12V power supply
line.
Check BL_EN signal and circuits around
CN801.
Check BRT_VR signal and circuits around
IC603.
Signal waveforms of test terminals LD303,
LD304 (LD310, LD311) are normal?
Signal waveforms of test terminals LD305,
LD306 (LD312., LD313) are normal?
Signal waveforms of 31st and 32nd pins of
IC401 are normal?
Check SW PWB and SW cable and their
connections.
48th pin of IC601 is in H level (DC+3.3V)?
continued from 1
LD618 is H in level (about DC+1.9V)?
Check SW PWB and SW cable connections.
Test terminal LD804 is DC+12V?
LD800 is in H level (DC+5V)?
Check lamp inside LCD module.
Check circuits around IC601.
Check Q600 and its surrounding circuits.
Replace inverter PWB unit with a new one.
Check circuits around IC601.
Check Q600 and its surrounding circuit.
Check circuits around IC300 and IC301.
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