Help Identifying Which TV Board to Replace

[tom565]

Hi. I have a Sharp LC-C6577UM TV that won't turn on after a lightning storm. It acts completely dead. The power button or remote won't do anything. I don't hear any clicks or see any any lights on the TV.

I would like to diagnose the board that is causing me the issues so I can replace the whole board. I understand that it could be more than one board that is damaged. I do not see any visual issues with any of the boards, front or back.

The main board has no voltage outputs on any terminals. The power board has no outputs on the lower left terminal pins. There are three upper left plugs that do have voltage outputs on the power board.

#1
Black Wire-55v
White Wire-68v

#2
Black Wire-55
White Wire-68

#3
Black Wire-63
White Wire-63

[vinceroger69]

Re: Help Identifying Which TV Board to Replace

In picture 1 the main board is under that metal cover bottom left can you take some pictures of that board thanks

[R_J]

Re: Help Identifying Which TV Board to Replace

Those voltages you are measuring (#1,2,3) are from chassis ground to the HOT side of the power supply, thats why they are wrong (50-60 volts)
You have no standby voltage.
With no BU5V I suspect ic7905 is bad, Check the resistance of R7918, R7853 and R7914 the first two should be less than 1Ω R7914 should be 2.2Ω

[tom565]

Re: Help Identifying Which TV Board to Replace

Vinceroger69, sorry for the wrong description on the "main board". Here is a picture of the actual main board that's under the metal cover. It has no power anywhere on it.

R_J, the #1, #2, #3 voltages were measured from the wires to the TV frame. I will try to get some OHM measurements tonight of the components you mentioned.

Thanks for the help so far.

[vinceroger69]

Re: Help Identifying Which TV Board to Replace

link to the service manual if you dont have one
https://www.manualslib.com/manual/91...c-60e77un.html

[R_J]

Re: Help Identifying Which TV Board to Replace

This is the standby section, You need to have BU5V, If R7914 is open, it is very liklely IC7905 is bad.