Vizio 47 vo47l

[splitcrete]

Hi all I have been rebuilding the boards on this tv for a while now.
Now I an stumped There is a symbol on the back side of my power supply
marked with a black arrow . I have no clue as to what it is. It is under a transformer. Any one know what it is?

[budm]

Re: Vizio 47 vo47l

That is the Thermistor (can be Positve or Negative type) for temperature sensing, OTP= Over Temperature Protection. It looks like Negative type (NTC).
What is the power supply not doing?

[splitcrete]

Re: Vizio 47 vo47l

No 24 volt

[splitcrete]

Re: Vizio 47 vo47l

The transformer that it is under will not power up.

[splitcrete]

Re: Vizio 47 vo47l

Its the big transformer at bottom of picture.

[splitcrete]

Re: Vizio 47 vo47l

I just checked the thermistor By warming it up with my solder iron and the resistance goes up . It is a negative type heat will increase resistance. A PTC is positive and the resistance goes down when heat is applied. Thank You BUDM for telling me what it was.

[budm]

Re: Vizio 47 vo47l

Negative type, resistance goes down as the the temperature goes up, opposite reaction for PTC.
Do you get about 380~400VDC at the two legs of the main 450VDC filter cap when PS_ON is applied to the power supply board? Board numbers?

http://en.wikipedia.org/wiki/Thermistor

[splitcrete]

Re: Vizio 47 vo47l

I will have to solder a couple wires under the board to find out.The cap is in a heat sink cage.

[budm]

Re: Vizio 47 vo47l

For the 12v/24v switched power supply to work, it will need PS_ON, PFC Voltage booster circuit to work to supply 380~400VDC for the power MOSFETs that drive the 12V/24V transformer to run on.

[splitcrete]

Re: Vizio 47 vo47l

Its getting late here I will report back tomorrow. The set I am working on has all volts good but no 24 volt from the big transformer. I changed all the radial caps but not the big one. And I changed all the regulators on the inverters, and main board.All fuses good pson is good and back light control voltage is good,and the panel is good too.Need sleep now I don't need to fry myself working on this piece of crap. Thanks BUDM good night

[splitcrete]

Re: Vizio 47 vo47l

OK I had to check I am getting 398 volts.

[budm]

Re: Vizio 47 vo47l

OK, that is good, so we need to concentrate on the 12V/24V drive circuit next. We will have to trace out the connections on the board. Do you have P/N of this board, we will need good clear pictures of both sides of the board, they must be good enough to clearly see the traces.

[splitcrete]

Re: Vizio 47 vo47l

I have p/n and I will take some good pictures right now.
board number is 0500-0510-0340 be back in a couple minutes picture time.

[splitcrete]

Re: Vizio 47 vo47l

Got the pictures you asked for

[splitcrete]

Re: Vizio 47 vo47l

Wrong picture

[splitcrete]

Re: Vizio 47 vo47l

try this one

[addytzu123]

Re: Vizio 47 vo47l

Hi,

The correct PS name is DPS-433BP , but unfortunatley I was unable to find a schematic for it!

[splitcrete]

Re: Vizio 47 vo47l

I don't see a fuse but here is a picture.

[splitcrete]

Re: Vizio 47 vo47l

Vizio didn't put out a schematic For this PS

[Shane711]

Re: Vizio 47 vo47l

Did splitcrete ever figure out the problem? I am having the same problem, no 24v. I can not find the problem. There is 2 OPT Thermistors on the board and both read about 4 ohms with the board unplugged. I need help with this one.