LG 60LB7100 Schematic

01-14-2016

SMPS Trouble LED blinks 3 times

then

only 2 times

Alvie Rod

60LB7100 Intermittent Backlights

LG Electronics Training Center, LGEAI, U.S.A.

• Backlights Blink

• Backlights go off

•

• Note: This panel was a Refurbished panel from parts.

01-14-2016 ver 3

gers C.E.T.

.

Situation During Testing:

completely

for backlight grounding signals, all but two test points were reading approximately 4V. But

But t

(EL55

EL64). Backlight P

56V

Installed a Refurbished panel from Parts into our 60LB7100.
Panel P/N: CRD31515701
TV ran for 4 days, 24 hours a day until symptom showed up.

Findings:

• The backlights would begin to blink. Usually 4 to 6 times then they would shut off
.

• SMPS LED was blinking 2 times indicating DC-to-DC converter problem.

• However, when watching the SMPS trouble LED while the backlights were blinking, it

blinked 3 times once or twice then it went to 2 times after the backlights went off. 3 times
indicating Open LEDs.

• While Backlights were blinking: Reading the test points EL50-EL54 EL62-EL67 on the SMPS

two of them were reading 0V, (EL55 and EL64). Backlight Power was 70V.

60LB7100 Intermittent Backlights

• While Backlights were off: Reading the test points EL50-EL54 EL62-EL67 on the SMPS for

backlight grounding signals, all but two test points were reading approximately 7V.

wo of them were reading 0V,

and

ower was

• Note: In this model there are only 6 backlight drivers. So two test points are tied together

per/driver.

• See next page for further details

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