vizio vp50

[tom66]

Re: vizio vp50

The test is not sufficient, as you do not have cycling outputs, you have -low- outputs. These components very rarely fail shorted, they tend to drift instead.

You need to set it up with 1kohm resistor from 35V~5V to K, then connect K-R, you should measure 2.495V +/- 2% across A-K.

[heavymachines]

Re: vizio vp50

=tom66;304806]The test is not sufficient, as you do not have cycling outputs, you have -low- outputs. These components very rarely fail shorted, they tend to drift instead.[/QUOTE]





so to make sure we are on same page, your saying because i have low voltage output on power board, the tl431 may pass the bench dmm test but still can be bad because of leaking current from the tl431 thus causing "drift" in voltage..


and it being right next almost butted to the heat sink probably cause this malfunction perhaps? likely scenario?




You need to set it up with 1kohm resistor from 35V~5V to K, then connect K-R, you should measure 2.495V +/- 2% across A-K.[/QUOTE]


I wish i knew exactly what your saying,,, how to set the 1kohm and k-r etc...is there a demo how to do this ? i mean via youtube or net somewhere.. i am kind of a hands on person once i do it and understand what i am doing...the more i like doing it... still quite green horn in comparison to many on this forum..

[tom66]

Re: vizio vp50

No, I am saying that you have low outputs for some reason.

I don't know why but it could be the TL431.

The best thing to do is to test the TL431 using the method I described, so it can be ruled out.

All I know is these LGs had a batch of dodgy xx431 and it was causing my problem with an LG plasma -- clicking on and off, no power. I bypassed the opto but a TV friend of mine told me it's a common issue and the proper fix is to replace the 431.

[heavymachines]

Re: vizio vp50

i tried edit the post and its not highlighting your statements apologies ahead of time..

[tom66]

Re: vizio vp50

Can you get hold of a breadboard?
http://www.ebay.com/itm/Red-Solderle...item5651cbea9d

You can put the component on it and wire it up. All the columns (except for at the break) are connected to each other.

[heavymachines]

Re: vizio vp50

No, I am saying that you have low outputs for some reason.

I don't know why but it could be the TL431.

The best thing to do is to test the TL431 using the method I described, so it can be ruled out.

All I know is these LGs had a batch of dodgy xx431 and it was causing my problem with an LG plasma -- clicking on and off, no power. I bypassed the opto but a TV friend of mine told me it's a common issue and the proper fix is to replace the 431.

okay just so you know it's a samsung.. but i guess very possible samsung got some dodgy ones as well.. being a brand specific TL431



okay i will do that test will be monday when i get back to the rest of the tv..

[tom66]

Re: vizio vp50

Yeah budm pulled one from a Samsung monitor too, low rail voltages.

[heavymachines]

Re: vizio vp50

Can you get hold of a breadboard?
http://www.ebay.com/itm/Red-Solderle...item5651cbea9d

You can put the component on it and wire it up. All the columns (except for at the break) are connected to each other.

Actually i think i can.. my cousin 15 miles from me has a big breadboard..their dad passed some time ago and he was a electronics engineer.. and they still have a lot of his equipment ..rat shack i imagine has some that's closer.

[heavymachines]

Re: vizio vp50

okay got a bread board and 1 k resistor... ready for instructions thanks for helping me and i am eager to learn...

its this one if it means anything http://www.radioshack.com/product/in...ductId=2734155

[tom66]

Re: vizio vp50

Plug in xx431 so it goes across multiple columns.

Pin 1 is the leftmost pin you see when you look at the device directly on label side front, curved side back.

Pin 2 is middle, pin 3 is rightmost.

Pin 1 goes to pin 2, use wire.
Pin 2 goes to ground, use wire to connect to rail at bottom of board.
Pin 3 goes through 1kohm resistor to positive supply, use rail.

You need a 5V~35V supply; a 9V battery, phone charger, lab power supply etc will all work.

Take photo of configuration before you turn it on.

[heavymachines]

Re: vizio vp50

never mind i found what you meant by

pin 1 reference (R)
pin 2 anode (A)
pin 3 cathode (k)

okay see what my results will be....and can use anywhere from 35 volts to 5 volts for input?

[tom66]

Re: vizio vp50

yes.

[heavymachines]

Re: vizio vp50

Plug in xx431 so it goes across multiple columns.

Pin 1 is the leftmost pin you see when you look at the device directly on label side front, curved side back.

Pin 2 is middle, pin 3 is rightmost.

Pin 1 goes to pin 2, use wire.
Pin 2 goes to ground, use wire to connect to rail at bottom of board.
Pin 3 goes through 1kohm resistor to positive supply, use rail.

You need a 5V~35V supply; a 9V battery, phone charger, lab power supply etc will all work.

Take photo of configuration before you turn it on.

so i loop pin 3 with 1k resistor back to pin 1 use rail.. if i am understanding correctly?

[heavymachines]

Re: vizio vp50

so i loop pin 3 with 1k resistor back to pin 1 use rail.. if i am understanding correctly?

never mind dumb question..

[heavymachines]

Re: vizio vp50

okay what you think for first try?

[tom66]

Re: vizio vp50

Looks good! Measure the voltage pin 3 (or opposite end of resistor, not end on positive rail) to ground.

[Baileybum1234]

Re: vizio vp50

okay what you think for first try?

Whats the white resistor looking thing guys?

[heavymachines]

Re: vizio vp50

okay the worn down 9 volt battery is outputting 7.64 volts

measurement at pin 1 and 3 on tl431 is reading 7.64 volts

[tom66]

Re: vizio vp50

That is not right; is battery definitely the right way around?

[heavymachines]

Re: vizio vp50

Whats the white resistor looking thing guys?

there is the 1k resistor with color bands and the white jumper wire in line with it as the white wire in this is positive in this setup... to the battery er power source...