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Low voltage on voltage inverter board

I have 12 volts going to the voltage inverter board coming from the main board until I plug the connector into the inverter board. Then, it drops to about 5 volts. If I connect an external 12 volt 1 amp DC adapter to the 12 volt lead, the voltage comes up to almost 10 volts and I can see the picture good. There is no sign of any burned components and all other voltages look fine. Any help would be appreciated. Thank you very much

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Probley got a week capacitor in the 12 volt supply, but without even a make or model number your guess is as good as mine

Posted on May 15, 2008

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Posted on Jan 02, 2017

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Hi Ab7775,

1. Pl check st by 5 or 3.5 volts.

2. If it is ok, check power on 5 or 3.5 volts. Is power on voltage stable ? If this is pulsating with cliking sound, it is the main board. Otherwise it should be the power supply.

3. Please also check all the other voltage for short with ground.

You can also check the power supply board separately. Remove the connector going to main board. Put a 1k res between st by and power on pin. Plug in the ac, if all the voltage appear, your power supply is ok.

I am on line if possible please do this checking and let me know the result.

Good luck.

Aug 09, 2016 | Samsung Televison & Video

1 Answer

Vizio TV model E470i-AO with no backlights, was able to see the menu and run netflix with a flashlight and hear sound. Do you think is the power supply or the actual backlights?

Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis.
To some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement. To some models sets, the back-light inverter and SMPS section circuit will be integrated at its main board itself. If so; the main board should be replaced. To some models of sets, all these section circuit will be integrated at its main board. If this is the case, you have to replace the main board.

Feb 18, 2016 | Vizio Televison & Video

1 Answer

TV won't come on.

Is the red light on? Does it change to blue when you press the power button?

If the red light is lit, part of the power supply is working to provide the standby voltage. If it is not lit at all, check to make sure power cord from the mains power (wall outlet) cord is securly and fully inserted in the back of the set. If it still remains dark, the power supply is the primary suspect.

If no light, initially check the fuse, it is 5 Amps and a little smaller than a mini marshmallow. It is located on the right side of the board as you face the back of the set. It will be in the vicinity of the connector comming up from the power cord adapter. To test this, check other voltages as described below first, as the power supply board must be removed to get at the bottom leads of the fuse.

If the light simply remains red no matter what button is pushed, the power supply board is the first place to check for faults. If you have a voltmeter, unplug the set and remove the center plastic panel of the set, this reveals a metal plate, which is retained by three more screws along the bottom. The base can remain in place.

With that plate removed, use care when it is plugged in as there is lethal v voltage potential on the right side of the opening as you are facing the back of the set. There will be two boards, the one on top with the metal plates visible is the power supply. The lower board processes the inputs into video and audio components and is the "A&D board", These are important to know if you are buying them off of Ebay or other internet vendor.

With the set unplugged look for a mounted connector on the left side near the top where 2 sets of multiple wires come out of it and plug into a pair of connectors on the lower side of the power supply board (Black,red and another color) There are multiple red and multiple black wires- in the mounted connector, there is just enough room to insert a probe tip with a little bit of force, just enough to ensure the tip is in contact with the conductive connector in 1 each of the black; insert the black test lead from the meter, and the red test lead of the meter to one of the red in the larger mounted connector. The several red wires attach to the same copper pad on the power supply board so only one measurement needs to be taken to determine if power is available for the inverter board or boards. The black wires attach to one pad as well. With the meter set to it's highest DC voltage scale, plug the set back in and switch to lower scales as needed to ***** a avoltage measurement. see if you have a voltage in the area of 24 volts. If you do- check the fuse(s) on the inverter board or capacitors of same boards (depends on production run.

If you have 24 volts, the blue pilot lamp should be lit on the front. You can see on the face of the set if the tubes are lit or not. If you have 24 volts but no light- the fault is with the inverter or the CCFL tubes. The inverter should be pretty obvious if it is the issue because the capacitors will have bulging tops. The chip fuse for each section should checked for continuity If there is, the fuse is good. These require a high ripple current type of electrolytic capacitor. A general purpose type will not last in this location.

If the set has the CCFL's lit, but no response to an input signal, move the test leads carefully, or unplug set to move them to the corresponding red and black wires of the bundle that plug just above the paired sets that go to the inverters, the upper set has 3 red, 3 black, and 2 other colors on the connector. You should see a voltage measuring between the red and the black. If no voltage, or less than about 3 volts, the power supply board is at issue. If the voltage is greater than that, the A&D board is likely at fault, this is the board that is below the power supply board..

Dec 11, 2011 | Polaroid Televison & Video

2 Answers


You need to check inside the set to see if the main board has 5 volts going to it on one of the white fuses on the board. If it does then it is likely that the main board (one with all the jacks) is not turning on the power supply to the inverter board so the screen will light. To confirm the power supply is working you need to check for the 12 volts and 24 volt from the power supply plug. If especially the 24 volts is there then you have a bad inverter board. Usually located on one side of the chassis. Check for domed capacitors. A capacitor is a cylinder shaped component with a positive and negative connection. A bad one will be pooched up at the top. Check the power supply for these as well and replace with the same mfd and voltage rating.

Nov 02, 2011 | Sanyo DP42849 42 in. HDTV

1 Answer

My tv is plugged in but wont turn on, there is a green flashing light (timer) how do i fix this?

hi sir good day the green light indicator flashing which indicates error detected by processor. now here is my solution on how will you fix the problem. if you are going to do it with your make sure you have proper tools and at least a basic knowledge in repairing. now unplugged the unit then open the back cover to gain access the internal part of the tv. now disconnect the connector wire going to inverter board for back light then turn the tv, if the indicator stays green doesn't blink then all the voltage out put from the power supply is normal the 5v stand by,5v switch, 12v and 24v are present, you have bad inverter board or the back light itself. another way is if you disconnect the connector wire going to inverter ballast board then still light indicator flashing and no PS_ON voltage coming from the main board which switch the power supply to turn on i may say you have bad processor board. make sure no bulging capacitors at the power supply replaced it with the same value a panasonic brand FM or FC series much better with low ESR 105c rating. you can find replacement parts at . hope this will help you feel free to ask further question good luck.

Aug 20, 2011 | Televison & Video

2 Answers

Akai LCT2662 won't turn on, indicator solid orange

Any luck getting this fixed?Please let me know.Thank You very much!

Jul 13, 2010 | Akai LCT2662 Television

4 Answers

Westinghouse HDTV TX42F430S, No picture or sound.

From where do you get the 3 volts to feed the master inverter board?
Have you measure all the voltages from the power supply to the main board?
Since the screen is ON when applying the 3.3 volts and the CCFL lights are ON, the backlight inverter boards and the CCFL lights are working. At this point there could be a LCD controller inverter board failure but if that is the case, you could still have audio but no video.
I have the module from a TX47F430S that had a broken screen, the 42 and 47 inches use the same parts.
Let me know if you need further assistance.

Mar 17, 2010 | Westinghouse TX-42F430S Television

1 Answer

Protron PLTV-3250 back light inverter? Hello, How are you doing, I have a Protron LCD model# PLTV-3250 that was given to me and at the time not working. Unless I was not checking things correctly with my...

I use hair dryer for locating bad electrolytics capacitor for almost 30 years. When its warm up the chemical reaction works more than when it is cold, that is one symptom of bad electrolytic cap. When you cool down the cap with freeze cooler then the set will stop working again. I would say go ahead and replace those capacitors on th inverter board, make sure to use low ESR capacitor such as PANASONIC FM series from DIGIKEY.COM. I use these cap for repair for many many years with great reliability. The inverter board should have 24vdc feeding it.

Dec 09, 2009 | Protron PLTV3250 32 in. LCD Television

2 Answers

Same problem. red light flashes 3 times, but will not turn on.


The blinking light means the controller QA01 in the AV_TERM system board is booting and driving the TIMER/REC RED LED light accordingly. This failure mode is true for many conditions, not exclusively for the main PS board PE0071. It could be caused by many things, LOW B, SEINE, AV_TERM, LCD, PROTECT, etc.

Specifically for PE0071+12VDC circuit failure, which is the most common , listen for the LINE relays SR80, SR81 coming online. If several (3) or more clicks are present when applying power to the TV set then suspect the +12, 20, +32 VDC inverter is faulty.

As a quick check, you can disconnect P807B. If the relays cycle every 1-2 seconds then is most definitely the +12VDC inverter. Check for voltage level at optocoupler Q881 pin 4 and this should not be cycling. This point is the VCC for the oscillator. Repair or replace board 75002913 as necessary.

TROUBLESHOOTING: (this is my own, not the OEM !, try at your own risk!)

  1. Check for LINE1 input voltage level at inverter on sheet [4].
  2. Check for LINE2 input voltage level at inverter on sheet [3].
  3. Check for STBY +5VDC & +25 VDC ( observe correct GND REF) page [4]of PE0071 POWER
  4. Check for +22 VDC out of regulator on page [3] out of Q822 Emitter
  5. Check P809B connector for :
  • P809B (12) POWER = 3.00 VDC (+/-0.2)
  • P809B (11) POWER_SIG = 0.00 VDC (HIGH to Power on TV)
  • P809B (10) PROTECT = 0.00 VDC
  • P809B (9) ACDETECT = 3.00 VDC (+/-0.2)
  1. Check for PFC_OUT = 368-371 VDC
  2. Check for +12, +20 & +32 VDC inverter page [5] of schematic manual.

For +12 VDC Inverter, suspect components:

Q880 STR-W6765 PSR (works really hot!!)
D884A and related switching circuit components.

Good luck,


Jul 03, 2009 | Toshiba 42HL196 42 in. LCD HDTV

1 Answer

Hisense TL2020 LCD TV

You should check the 12 volts capacitors on your power supply for dry or leaky, bulging conditions.
Replacing those capacitors will restore the functionality of your TV.

May 15, 2008 | Televison & Video

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