LB-1085 - Sharp Monitor Service Manual (repair manual). Page 50

TROUBLESHOOTING

7 – 3

3 LAMP ABNORMALITY

*

The backlight does not light up, or lights up instantaneously but turns off soon.

Is each output 

voltage supplied from 

each power PWB?

No

No

Identify 
the PWB 
which is 
not lighted

Yes

Yes

Yes

Yes

Abnormality

Refer to "4 The power is not supplied."

No

No

Replace the abnormal parts.

Lamp OFF check
While pressing [CH_Down] + [VOL_UP] of the main unit, 
forcible rise the power with AC_ON, and look for the 
lighting/preheat PWB whose LED is not lighted. 

Use a tester to check the resistance across the HCFL 
connector of the PWB which is not lighted and identify 
the lamp which is open. (Normally 1.8 - 2.2

Ω). 

Replace the HCFL which is open. 

Is there no abnormality in the main/power interface PWB 
and the related sections?

Is there no abnormality in the cables and the connectors?

Is there no abnormality in the main PWB?

Is the STB signal normal?

Check the connector 

BK - LB line. 

Are the inverter 

control PWB and 

its connector cable normal?

Are each inverter PWB

/preheat PWB and 

their connector cable 

normal?