Vizio VP422 Plasma Wont turn on-Orange Vizio Light Help - AVS Forum
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post #1 of 18 Old 04-02-2013, 09:17 AM - Thread Starter
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Good Day all;

I got the VP422 42" from a family member; they said they were watching a movie and it just stopped working and would not turn backon.

First thing i did was check fuses; the main fuse by the input was good; but there in the center towards the top the T4amp 250v fuse (See photo) was blown. I've replaced it and applied power (plugged it in) there are 2 clicking sounds come from the PS unit when it gets power (Sounds normal i guess never owned a Vizio but sounds normal); the visio light is Orange; no reaction or clicking when i press the power button. One green LED on sub-board off the PS board.

I can't find an exact match where someone had similar problem I'm still TS the issue with multimeter to insure the PS is the issue or not before i waste money. Caps are all good; no bulges. Rev of the PS board is 1.1

So far this is my Power outputs.

AC_Det = 5 v
Lamp (top one w/ orange wire) =.4v
5vsb = 5.2v

No other power.. no power at all when you press the Power button from the PS_on.. no power output from either side vS or anything. All other fuses good. Only that center one was blown (Which I've replaced and has not blown again. Does this sound like a problem PS board or Main board> ? IMG00301-20130402-1044.jpg 285k .jpg file IMG00302-20130402-1044.jpg 453k .jpg file IMG00303-20130402-1044.jpg 153k .jpg file IMG00305-20130402-1107.jpg 691k .jpg file

There are no other LED's of any kind other than the Orange Vizio logo front and one green solid LED on teh sub board of the PS Board. Any input would be great. See attached photos.
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post #2 of 18 Old 04-04-2013, 08:29 AM - Thread Starter
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Any help would be great.. I'm at a loss on what board to replace.
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post #3 of 18 Old 04-05-2013, 12:39 AM
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Does this set use a Samsung PDP?
Could be the common QX801/QX802 failure on power board.
Power board is hard to get hold of so you'll need to repair it.
BTW: Nice scope wink.gif
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post #4 of 18 Old 04-05-2013, 06:47 AM - Thread Starter
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Good Morning and thank you for responding; I'm hoping i can find the actual problem of this TV with out dropping a lot of parts in it I don't need; I can buy this same tv at Wally World (LOL @ that) for $400 bucks so i'm not looking to spend much.

It does have the Samsung Labels stamped on all the boards.

R1.1 (8/3/25)



What is QX801/QX802 problem and how do i go about diagnosing to make sure? I have a MM i can test with.. also just to note; there are no buldging CAPS on this board it actually has far less than what most with the problem on the LCD version (with those problems) has. So i think I'm good there.
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post #5 of 18 Old 04-05-2013, 06:52 AM
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Would need to see an overall shot of the PSU board. But QX801 and QX802 are FETs on the heatsink, which can quite often fail.
See here for someone fixing the 50" PSU, same issue I think.
https://www.youtube.com/watch?v=dVaC2KVVLvs
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post #6 of 18 Old 04-05-2013, 07:07 AM - Thread Starter
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If you look at my attached photos on the first post; 1044.jpg is the overall board.. do you need a better close up of the board?
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post #7 of 18 Old 04-05-2013, 07:10 AM - Thread Starter
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Granted this is a guy off E-bay that is supposed to be a TV Repair shop selling a main board; I had asked the same basic question on rather my problem sounded like the main board not supplying the pSon power to power up or the actual PS board.. (Granted he's trying to sell a main board so take it with a grain of salt.."

His response just for the record:

"I can't be sure without checking it. However the last one I worked on I fixed the main board and discovered the fault on the main blew the power supply.
I had to change out the power supply and I fixed a regulator and a fuse on the main. I would suggest the main and see if that fixes or at least gets us closer."
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post #8 of 18 Old 04-05-2013, 07:44 AM
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This is utter nonsense: "However the last one I worked on I fixed the main board and discovered the fault on the main blew the power supply."

A main board cannot damage a power supply.

You have a blown fuse. The power supply is defective. The main board did not do this.
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post #9 of 18 Old 04-05-2013, 07:51 AM - Thread Starter
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IMG00306-20130405-1149.jpg 530k .jpg file I understand thanks for your honest response; I work digital X-ray Equipment that is basically kind of*** similar to these boards..; sometimes a short else were or over power will blow a fuse.. that's why i did not just want to pop a new board; whats troubling me is the facti put a fuse back in and its yet to blow.. just wont power on or do anything; unless the fault that blew the fuse is in the PS board and is already damaged to a point where it wont pop the fuse again..

We use a P2 power board that gives power to an inverter board that powers the Tube head on the X-ray.. the Inverter board if there is a fault can cause the P2 power board to go up in smoke or pop fuses.. but in this case because the main board has both input power and output power back to the ps board to tell it to kick on that's why I'm trying to figure out for sure or not what board it has.. I'm used to simple on/off switch on our equipment LOL..

I need to stop thinking like im working on an x-ray machine and think like a TV.. Welcome to Diagnosing a tv.. LOL>>>

I will try and watch that video; if you have any quick steps in checking what your talking about above please let me know.. Ill watch the video and try and see what i can come up with.
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post #10 of 18 Old 04-05-2013, 09:56 AM - Thread Starter
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So i went through doing testing.. cant find anything wrong.. Everything that should be shorted is and everything that should not and have resistance does as the video shows; except they are mounted on the board so that's as far as an absolute as i can go. The two black caps had .25 DCV left in them; those are the big black ones... that connect directly on the board to the fuse (That was originally found blown but has not blown since)..

Excuse the built up dust bunnies and nicotine on the boards; Aunt is a heavy smoker. Everything looks ok on teh back of the board; the Caps on teh front are not buldging (but the big black ones as described before seem to have a cover over them which pooch up like there is an air pocket; you can push it and it comes back the same way.. I'm at a great loss on this one.. I'm thinking about just buying a new power board but I'm really not convinced this one is 'defective' other than there was a poped fuse but has not poped since. I'm not sure what to make of this.

they have one locally about 20 mins away for $60 bucks.. any other advise or input i can check before i buy a new power board?
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post #11 of 18 Old 04-05-2013, 10:54 AM
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Check the two FETs I have highlighted in red. Meter all three pin combinations on 200 ohms. Power must be off.
Also confirm if I have correctly highlighted the fuse.
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post #12 of 18 Old 04-05-2013, 10:57 AM
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vp422.jpg 604k .jpg file

For post above.
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post #13 of 18 Old 04-05-2013, 02:39 PM - Thread Starter
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The fuse your circled is the one that was blown.. other 2 fuses were good. I beleive i checked those two but I dont remember the wife has the board going ot check a local shop to see if they have it or not. I told her to buy it if they did.. I'm really hoping the board is defective and if she gets a new one it fixes it.. I'm really not wanting to eat the cost of a board i didnt need.. ROFL..
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post #14 of 18 Old 04-05-2013, 02:51 PM - Thread Starter
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My wife did not get the board; the guy wants to TS both the main board and PS board; mind you this is a local shop not the guy i posted from in above thread.. So i will check the ohms out and post results.. stay tuned.. Thanks smile.gif
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post #15 of 18 Old 04-05-2013, 05:23 PM - Thread Starter
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Ok.. So i checked; both read the exact same thing..

From the picture you circled; 1 being top and 3 being the bottom of both 3 pin sets..

1 <-- Black
3 <--Red

(Or Visa Verse- reading comes out to be 99.9ohm

Any other combination yields a quick flash of numbers and the meter reads 1

For both..

Thoughts?
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post #16 of 18 Old 04-06-2013, 12:56 AM
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The pin numbering is arbitrary. Sounds like the device is failed gate-source. You will need to de-solder them and test them out of circuit.
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post #17 of 18 Old 04-07-2013, 07:55 AM - Thread Starter
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Thanks for your help; I have it fixed.. seems there was a few components bad. I just replaced the Power board.. being i dont have a heat gun.. thanks again.
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post #18 of 18 Old 04-07-2013, 10:49 AM
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Well, you don't need a heat gun to remove MOSFETs, but glad you fixed it anyway...
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