+3V3_STB(P100Pin7) is OK?Can notPower OnCheck AC input andPSUP100PIN1,2,4=24V isOK?(+24V)ON/OFFPOWER (P100PIN 10)is >2V?NCheck IR netCheck U100 andother componentsaround U1001ǃHave no anything, No backlight/No Video/No Audio etc...YYY1ǃCheck the RS232(P402) port information?2ǃCheck I2C is Working normally?3ǃCheck sys_clk(X500)=27MHz?4ǃCheck software normally?5ǃCheck U500 connect normally?Remote Power On12VPOWER(L114,L115,12V) IS OK?YNCHECK STB LEVERIF CHANGE(R156) ?NY Check PSUNYCheck 5V(U106+Q100 OUT,L102)=5V?Check VCCK(U107 OUT,L100)=1.1V?Check AVDD1V2(U105 PIN2)=1.2V?Check DVDD3V3(U104 PIN2)=3.3V?Check AVDD3V3(U109 PIN 2)=3.3V?Check DDRV(U111 PIN 2)=1.5VCheck DC/DC DETECT sectionYNNCheck IR net isOK?NY

TCL L39D3320 Service Manual