Have sound but no picture. If I shine a light at the screen I can see the picture. Samsung UN55H6203AFXZA. US01

While you have the back cover off, test the panel and power supply board by disconnecting the cable from main board. If unit's backlight comes on the main board needs replacing. If the backlight does not, the power board needs replacing.

1st thing I would look for is bulging filter caps. replace any that are.
this video may help also
https://www.youtube.com/watch?v=q8W8m_Xa-Lo

It has a reset button on the lower back right hand corner; push that button.

The back lit LED's go faulty frequently also if DC - DC inverters are used fpr driving the LED's they may be faulty
Do not attempt to repair the inverter , change the module .

Hi Peter,
This type of failure could be due to a defective power supply, or the LED backlight strips.
I would suggest to check the link below to find service parts to fix your TV or contact them.
Search results for UN55H6203AFXZA

I wonder if that TV has headphone or audio out jack? Sometimes when that jack fails it is getting shorted and TV automatically turns off internal speakers to send sound to headphones

first shine a light on the screen and see if you can see the picture if you can its the led board failed. this can be a bad led in the back of the screen or the power board for the leds. it can take a few angels to see the screen but if you can shine light in the back or at and angle on the screen you will find out the problem.

Does it have an image when a bright light is shined behind the screen?

Hi Anonymous,
Generally the parts work if the connectors are same. You may have to do some corrections in the service manu.

You're a technician work to earn I assume. Do understand; this is a forum to help one who knows a little; to make their sets right. Not a help you like people to turn revenue out of it. Understand? Do not know nothing; yet runs a service shop to cheat others!!!!! https://electronicshelponline.blogspot.com/