LL-T2020 (serv.man7). Troubleshooting - Sharp Monitor Service Manual (repair manual). Page 2

LL-T2020

TROUBLESHOOTING

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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 IC602 are in H level 
(DC+3.3V)?

LD613 and LD616 are in H level (about 
DC+1.9V)?

LD808 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 790 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 CN101 
(CN201).

Check SDA and SCL signals and circuits 
around IC402 and IC602.

Press INPUT key to switch over to the 
correct input signal port.

When CN802 cable is removed, check the 
LD801 is DC+12V.

Check inverter unit, inverter cable and their
connections.

Check the power unit and cable and their 
connections, and DC+12V power supply 
line.

Check BL_EN signal and circuits around 
CN802.

Check BRT_VR signal and circuits around 
IC604.

Signal waveforms of test terminals LD304, 
LD305 (LD317, LD318) are normal?

Signal waveforms of test terminals LD312, 
LD323 (LD313, LD324) are normal?

Signal waveforms of 31st and 32nd pins of 
IC402 are normal?

Check SW PWB and SW cable and their 
connections.

48th pin of IC602 is in H level (DC+3.3V)?

continued from  1

LD613 is H in level (about DC+1.9V)?

Check SW PWB and SW cable and their
connections.

Test terminal LD801 is DC+12V?

LD807 is in H level (DC+5V)?

Check lamp inside LCD module.

Check circuits around IC602.

Check Q601 and its surrounding circuits.

Replace inverter PWB unit with a new one.

Check circuits around IC602.

Check Q601 and its surrounding circuit.

Check circuits around IC301 and IC302.

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