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Hi,
I am trying to repair a Vizio 42" LCD HDTV, There is power going into the power supply board, but only 5 vdc coming out of one of the connectors. There are 12vdc and or 24 vdc coming off the power supply board.
The TV will be in stand by mode, but can not be turned on by either the power button or remote.
Ordered a refurb power supply and installed it with the same results.
Any Guru's out there have any other suggestions?
Even with all connectors out of the power supply board (Except the A/C), only have the 5 vdc coming out of the board.
From other post, someone suggested the Main board, but if the power supply voltages aren't there, then why would you consider a main board problem.
Correction to the above post. I am NOT getting any 12vdc or 24 vdc coming off the power supply board.Correction to the above post. I am NOT getting any 12vdc or 24 vdc coming off the power supply board.
Correction to the above post. There are NO 12vdc or 24vdc coming off the power supply board. Only the 5vdc is coming off the board.
Does anyone know if the main board switches the 12 and 24 volts off of the power supply board?
Tried the unplug solution.. same thing, Unplugged all the connectors from the main board and reseated all connectors.
Thanks again
Correction to the above post. There are NO 12vdc or 24vdc coming off the power supply board. Only the 5vdc is coming off the board.
Does anyone know if the main board switches the 12 and 24 volts off of the power supply board?
Tried the unplug solution.. same thing, Unplugged all the connectors from the main board and reseated all connectors.
dsacco86, Thanks for the reply. We reordered another power supply board because the company said it is possible that they might have sent out a bad board. Do you know off hand if the power supply board needs a trigger volt to produce the 12vdc, or 24vdc output?
I have been trying to test the power supply voltage, with just the AC volt going in, and trying to test for the DC Output off the board. The only thing that I have been able to get is the 5 vdc output. no 12 vdc, or 24 vdc. Just wondering if the power supply board needs a trigger volt to have it kick out the 12, and 24 vdc. Any help would be appreciated. Thanks in advance. Have a good day. Mac =)dsacco86,
Thanks for the reply. We reordered another power supply board because the company said it is possible that they might have sent out a bad board.
Do you know off hand if the power supply board needs a trigger volt to produce the 12vdc, or 24vdc output?
I have been trying to test the power supply voltage, with just the AC volt going in, and trying to test for the DC Output off the board. The only thing that I have been able to get is the 5 vdc output. no 12 vdc, or 24 vdc.
Just wondering if the power supply board needs a trigger volt to have it kick out the 12, and 24 vdc.
Any help would be appreciated.
Thanks in advance.
Have a good day.
Mac =)
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Macgyver do you have an email address i have the same issue with only 5vdc coming out of power supply no 12vdc or 24vdc. any help would be appreciated my email is [email protected]
The next thing I would check out is the power supply for the screen. Most manufactures call it a Backlight Inverter Board. If a part does go bad on this board, it would also cause the stand by mode or protection mode.
I'm sure there is a trigger. Sadly, I don't have the schematic for your TV to be sure which pins on the board to jump.
If the samething happens with the new ordered part, time to rule out the power supply and look at the Backlight Inverter Board.
With a main board detecting another bad board in the system, it will not throw the trigger. Therefore, staying in Protection Mode. I'm sure there is a trigger. Sadly, I don't have the schematic for your TV to be sure which pins on the board to jump.
If the samething happens with the new ordered part, time to rule out the power supply and look at the Backlight Inverter Board.
With a main board detecting another bad board in the system, it will not throw the trigger. Therefore, staying in Protection Mode.
I have a vizio sv420xvt i already replaced the Power supply & Back light inverter & still it won't turn on. So i'm going for the T-con board & the main board. Something has to work????I have a vizio sv420xvt i already replaced the Power supply & Back light inverter & still it won't turn on. So i'm going for the T-con board & the main board. Something has to work????
Yes i have tested All Caps & did find 3 bad ones on the Back inverter. so i'm going with tthe t con board & yes the main board!Yes i have tested All Caps & did find 3 bad ones on the Back inverter. so i'm going with tthe t con board & yes the main board!
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That problem is usually have 2 causes..Its either power supply board or main board..
Please take this steps on how to determine the problem: 1. Open the back cover. 2. Check the power supply output...It should have 5vdc for the main board..12vdc or 16vdc for the audio and 24vdc for the back-light inverter.. 3. If those 3 voltage supplies have encountered voltage drop...The problem could be on power supply board.. 4. If the power supply output is normal..The problem could be on the main board... 5. If the problem is power supply you should check if the capacitors are bulged on the top and try to replaced it..If you can't do that you can purchased new power supply board.. 6. If the problem is on main board there is no D.I.Y repair on that so you need to buy a new main board that fits to your TV.. Hope this solution will be helpful..
That problem is 2 causes,its either power supply or system board. This are some D.I.Y procedure for troubleshooting.
Open the back cover by removing all screws at the back.
Try to look at the power supply board and find the leak/bulge on top capacitors.If you found,replace it with the same type and ratings.
If the power supply doesn't have any leak capacitors.Try to power it ON to perform voltage checking.
Check the output voltage of power supply such as
5vdc,12vdc and 24vdc by using voltmeter.If this 3 supplies having a
voltage drop or flickering voltage while on power ON.Check the following
parts on the power supply,change value/open resistor,shorted transistor
and diode or repeat step # 2.
When the output voltage is stable and all parts looks
OK.The problem could be on system board.Unfortunately the system board
or main board is not for D.I.Y because the parts inside is very logic
and very sensitive.That is replaceable.
Tv power supply board have input and output high voltages issues.That the board,where the power a/c cord plug into it.Tries websites like Shopjimmy.com,Ebay.com to buy a whole refurbish power supply board for the replacement.
You can remove the back and check for bulged electrolytic caps on the power supply, you can also check to see if the power is putting out the right voltage, the the output voltage should be written on the power supply board by the connector. Also look at the inverter for cold solder connections.
you need to check first the power supply board whether the output supply 12-24vdc for the inverter board is stable and not flactuating..you can measure the output voltage with a multitester..you get a voltage output of 12-24 with the inverter board is connected or loaded to the system.be carefull of the high voltage at the inverter board..once the output is stable replace the inverter board or you can measure the output of the inverter be very carefull..the output range upto 500vac.be carefull..if the high voltage is stable replace the lamps...tnx and good luck..
On the power supply board there will be a connector that says PO which means power on from the main board. Make sure that goes High when you press the power button. Make sure your stby voltages are ok on the PS. If the PO goes High then the power supply needs repaired. A lot of the ic's on these boards are not available for us to buy, so you have to replace the board. If it doesn't go high then the main board is at fault, gets a little more tricky with that, but not impossible.
Does LCD screen backlight come on? If so proceed....
USE:CAUTION WHEN DOING THIS....
Try this if repairing yourself...find power supply, small board with no cover over it...check voltages on output pins/plug/connectors (white plugs) three in a row...
1 Plug has 24Volt supply..1 has 12Volt supply and 1 has 5Volt supply when read to ground (screw that holds board in) if you have these voltages it's a safe bet it's the main control board...I just replaced mine and it fixed a problem like yours.
Correction to the above post. I am NOT getting any 12vdc or 24 vdc coming off the power supply board.
Correction to the above post. There are NO 12vdc or 24vdc coming off the power supply board. Only the 5vdc is coming off the board.
Does anyone know if the main board switches the 12 and 24 volts off of the power supply board?
Tried the unplug solution.. same thing, Unplugged all the connectors from the main board and reseated all connectors.
Thanks again
dsacco86,
Thanks for the reply. We reordered another power supply board because the company said it is possible that they might have sent out a bad board.
Do you know off hand if the power supply board needs a trigger volt to produce the 12vdc, or 24vdc output?
I have been trying to test the power supply voltage, with just the AC volt going in, and trying to test for the DC Output off the board. The only thing that I have been able to get is the 5 vdc output. no 12 vdc, or 24 vdc.
Just wondering if the power supply board needs a trigger volt to have it kick out the 12, and 24 vdc.
Any help would be appreciated.
Thanks in advance.
Have a good day.
Mac =)
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