My tv went black - Toshiba 37HL67 37 in. LCD HDTV

Bring the engineer back. Tell him you followed his advice and now you have a new problem. He will do you a deal because he has been before.

https://www.fixya.com/support/r29790007-repairing_own_television

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https://us.community.samsung.com/t5/4k-8k-and-Other-TVs/Blank-black-screen-after-initial-power-on-but-gets-sound-Help/td-p/454769

please see your other post for response

Check and replace the back-light inverter baord.

Could be main AV board not receiving the proper voltage due to a failing capacitor or power transistor. So I suspect a PSU failure.

no power to tv light blinks on and off

most likely the power inverter, also suspect the p/s. best to have a trained tech check it. Julio at [email protected]

My Sony FD Trinitron TV did samething, started flashing, then eventually went completely black with volume. I got on internet searched found a solution, i tried it, it worked. unplug tv, remove all screws, remove back. towards bottom right theres a transmitter with a couple of knobs, we plugged tv in and moved knobs around and it worked. Also was extremally dusty, we used computer duster for a better connection. hope it helps you

check cold solder vertical circuit