JVC Service Mode

Press the {} MENU button and go to the User Menu screen, make sure 
hurt the indicator (arrow) is pointed and highlights the "Picture Control".

The buttons on top of the remote are set to TV & VCR respectively.

Set sleep timer minutes to "0" and while it can display, simultaneously 
press the {STATUS} & {VIDEO} DISPLAY buttons.

The main service menu will display your choices with # 1 through # 9th 
Press one of the number keys to enter Corresponding hurt menu.

Use the {+} CH {CH} buttons to navigate within the menu. 
Use the {VOL +} {VOL-} buttons to change the values. 
Use the {} MUTING button to memorize the changed value. 
Use the {} BACK button to exit the service menu.

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Turn the TV on. 
Using the remote control:

Press the {INFO}} & {MUTE buttons at the same time. 
The Service Menu will be display

Use the number keys to select the category. 
Use the {VOL +} {VOL-} buttons to enter the category. 
NOTE: Some models do not have category selection. 
Use the {+} CH {CH) buttons to select items to be adjusted. 
Use the {VOL +} {VOL-} buttons to change values. 
Press the {INFORMATION} button to exit.

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Turn the TV on. 
Using the remote control:

Press {DISPLAY MODE}} & {PIC buttons at the same time. 
The Service Menu will be display

Use the number keys to select the category. 
Use the {UP} {DOWN} buttons to enter the category. 
Use the {} {LEFT RIGHT} buttons to select items. 
Use the {UP} {} DOWN buttons to change values. 
Press the {DISPLAY} button to exit Twice.

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Press the {} MENU button. 
Select "Clock Set". 
Set clock to 3:21 AM and press "Start Clock". 
While the "Thank You" message is display on screen, press the {} and {MUTE MENU} buttons.

The Service Menu will come up. 

Use {UP DOWN} {} to select items. 

Use {{LEFT RIGHT}} to change values. 

To exit, turn the TV off.

Black Magic Chip for power supply units .

http://qfixit.blogspot.com/2018/04/quick-guide-led-tv-panel-repair.html?m=1