My tcl tv backlight issue

My tcl 55 inch tv backlight turned off when voltage less than 230 otherwise its fine.usually the voltage drops at night. What should i do?

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2889612:0crwdne2889612:0 0
crwdns2934285:0crwdne2934285:0