# [SOLVED] VIZIO GV42LFHDTV10A Not turning on



## tpi86iroc

Ok, heres the symptoms. Turn on TV and VIZIO light goes from orange to white and nothing else happens. No backlights no sound no picture. Have to unplug to get orange light back. Ordered new main board and installed and now have backlights and vertical lines which are multicolored on screen but still no sound or control and still have to unplug to get back to orange standby light. Sent that main board back and am awaiting another. Put original board back in and set just has original prob with just orange light turning white. Could there be something other than the main board causing this or did I just get a bad main board???


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## octaneman

*Re: VIZIO GV42LFHDTV10A Not turning on*

Hi tpi86iroc


Vizio has problem with their power supplies on their voltage regulators on the main boards there are 5 of them U2, U7, U8, U9, U33, the voltage outputs range from 1.8 to 3.3 volts, look for any bulging capacitors and replace them. If you are proficient with a DVOM you can perform a few tests on the connections that go to the main board. You should see these connections on both sides that connect to the main board from the power supply, the voltage readings should be around 18.5 volts to 1.5 to 5v respectively, anything lower will indicate a bad power supply. To identify the voltage regulators on vizio boards, its a 6 to 11 digit number usually start with AL or AP prefix, if there are 8 numbers with a hyphen the last 2 digits denotes the voltage output. 

You can save yourself a little money by replacing a few bad components as long as you know how to use a DVOM and a soldering iron. 

Warning !: There is a danger of electric shock which can cause serious injury or death. You will be dealing with high voltages going to and from the power supply, please do not attempt repair if you don't know what you're doing. 

Good Luck!


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## tpi86iroc

*Re: VIZIO GV42LFHDTV10A Not turning on*

Thank you Octaneman,
Yes I do know how to solder except not so good with SMT chips which seems is what these voltage regulators are and I know how to use DVOM. There are no bulging caps and I have located all 5 voltage regs. I do have a known good main power supply which I have swapped out only to have the same results on both my Main board and the one I sent back which I thought was bad as well. Il be getting a new main board hopefully Monday sometime. It would be nice to fix this main board just to say I did it. Gonna need to find my magnifying glass so I can read the Numbers off of the Voltage regs. I appreciate all the help uve given.


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## octaneman

*Re: VIZIO GV42LFHDTV10A Not turning on*

Can you get some readings off the voltage regs and the connectors? I'll do my best to help you troubleshoot the board if you're up to it.


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## tpi86iroc

*Re: VIZIO GV42LFHDTV10A Not turning on*

Ok I will when I have a chance. On the voltage regs which legs am I to put the meter on to get the voltage and can I use a common ground point to put the black lead on??? Im just not sure if the regulators are isolated from the common ground point.


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## octaneman

*Re: VIZIO GV42LFHDTV10A Not turning on*

You will need the datasheets of the regulators to find out which pins are the input and output voltages. If memory serves I believe you can use a common ground to get the readings. Start off by testing the fuses first there should be 2 of them, a 5v fuse and a 12v fuse. Do a continuity test and replace as needed. There is one thing you should know U33 is an adjustable regulator, the output voltage is adjusted by resistors where somewhere in the vicinity there are pads , the regulator is quite finicky and it burns out constantly. U33 is usually suspect because it feeds U7 and U9 on the board when dealing with screen problems like yours, so don't get fooled if you get low readings on both.



post back your findings.


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## tpi86iroc

Got new main board from UPS today and installed. Was not able to get voltages from voltage regulators from old board as that will be another project in the future. But for now my Vizio is now working again and now my kids can enjoy having a HDTV once more. Thank God it works, I was really getting frustrated. I still want to know what went wrong with my original board. Thank you Octaneman for the advice, im still gonna troubleshoot old board when I have a chance.


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## MisterD1947

*Re: VIZIO GV42LFHDTV10A Not turning on*



octaneman said:


> You will need the datasheets of the regulators to find out which pins are the input and output voltages. If memory serves I believe you can use a common ground to get the readings. Start off by testing the fuses first there should be 2 of them, a 5v fuse and a 12v fuse. Do a continuity test and replace as needed. There is one thing you should know U33 is an adjustable regulator, the output voltage is adjusted by resistors where somewhere in the vicinity there are pads , the regulator is quite finicky and it burns out constantly. U33 is usually suspect because it feeds U7 and U9 on the board when dealing with screen problems like yours, so don't get fooled if you get low readings on both.
> 
> 
> 
> I have a vizio 42" lcd tv U7 has very low output voltage but all others regulators check good including U33, the tv will not turn on but does have the standby orange logo light in the front , does not have the needed 3.3 volts at PSON terminal on Power supply to turn the tv on. U7 is ordered and I should get it soon, do you think it would cause this problem? Thanks


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## ghostiepeeler

Hello, I am having a similar problem, slightly different but I am suspicious of the main board, volt regs. I have pulled the volt readings but they don't mean a whole to me cause I can't find the data sheet. Help?!?!

Thanks so much!!!


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## Kefali

You might wait a long time because you've hijacked a discussion marked [SOLVED].

I recommend you start a new thread and state the exact symptoms and exactly what help you need.


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