VIZIO V037L FHDTV20A powers up, backlight on, sound works, buttons work, no picture

[triplefour]

Re: VIZIO V037L FHDTV20A powers up, backlight on, sound works, buttons work, no pict

yeah thats what i thought too, thanks for clarifying

hmm so a resistance tells us there is another component between that pin and the capacitor? and you are assuming it would be a MOSFET?

[triplefour]

Re: VIZIO V037L FHDTV20A powers up, backlight on, sound works, buttons work, no pict

is there no way to get a schematic for this board? or would i be able to tell more by flipping the board over?

[budm]

Re: VIZIO V037L FHDTV20A powers up, backlight on, sound works, buttons work, no pict

"hmm so a resistance tells us there is another component between that pin and the capacitor? and you are assuming it would be a MOSFET?" That is it, you need to find the one that shows less than one Ohm, so just have to start probing all the devices close by that area, one those device must be the one.

[triplefour]

Re: VIZIO V037L FHDTV20A powers up, backlight on, sound works, buttons work, no pict

so im going to keep one probe on the top left pin of the mx-12G MOSFET
and touch any other mosfet's around that area? and look for one that has less than 1ohm resistance?

[budm]

Re: VIZIO V037L FHDTV20A powers up, backlight on, sound works, buttons work, no pict

You will keep one probe on pin 30 of J8 or the positive leg of the cap CE65, then use the probe on other semiconductor devices that may have 3 pins or 8 pins, one of device will show <1 Ohm. Using pin 30 will be the easiest.

[triplefour]

Re: VIZIO V037L FHDTV20A powers up, backlight on, sound works, buttons work, no pict

ok i tested the resistance between the points circled in the picture and i got .03 or .04 so the top left pin of the mosfet is going directly to those 2 points?

[budm]

Re: VIZIO V037L FHDTV20A powers up, backlight on, sound works, buttons work, no pict

Is it .03 Ohms, or .03K Ohms on the meter? it should show the same resistance when you touch the two probes of the meter together.

[triplefour]

Re: VIZIO V037L FHDTV20A powers up, backlight on, sound works, buttons work, no pict

i have my meter on the lowest setting "200ohms" so when it says .03 i beleive it to be .03 ohms

[triplefour]

Re: VIZIO V037L FHDTV20A powers up, backlight on, sound works, buttons work, no pict

when i touch the 2 probes together i get 0.02 resistance

[budm]

Re: VIZIO V037L FHDTV20A powers up, backlight on, sound works, buttons work, no pict

If that is the case, then that pin should show the same voltage reading as shown on pin 30 of J8 then, please verify.
If is does show the same reading, then next thing we need to find out which one of the pin of that IC has 12Vdc on it.

[budm]

Re: VIZIO V037L FHDTV20A powers up, backlight on, sound works, buttons work, no pict

I am still not believe that is MX-12 because there is white pad the right of it with printing that looks like the indication for FIRMWARE version for VO37 AUO for that MX IC.
I would try probing some more resistance between pin 30 and some other devices to see if it also shows <1 Ohm.

[triplefour]

Re: VIZIO V037L FHDTV20A powers up, backlight on, sound works, buttons work, no pict

what do u mean? it says mx-12G right on it...hang on checking voltages

[budm]

Re: VIZIO V037L FHDTV20A powers up, backlight on, sound works, buttons work, no pict

OK, I verify that MX-12G, it is not the MOSFET we are looking for,
MX-12G 25L3205DM2i is the serial flash chip.
http://www.alldatasheet.com/datashee...5DM2I-12G.html

[triplefour]

Re: VIZIO V037L FHDTV20A powers up, backlight on, sound works, buttons work, no pict

ok if we say the top left pin is pin1 voltages on the mx12g are
1. 3.29
2. 3.29
3. 0
4. 0

5. 3.29
6. 0
7. 3.29
8. 0

voltage to cb57 and cb58 on the sides circled is also 3.29v
but the voltages on the other side is 0

im getting a bit confused here. there is no 12v coming out of the mx12g at all

[triplefour]

Re: VIZIO V037L FHDTV20A powers up, backlight on, sound works, buttons work, no pict

wow how'd u find that datasheet i was trying so hard!

[budm]

Re: VIZIO V037L FHDTV20A powers up, backlight on, sound works, buttons work, no pict

See post 93 I just updated, it is serial flash, not the MOSFET we are looking for.
When I saw that white pad with those info, then I know it is not the one we are looking for.

[triplefour]

Re: VIZIO V037L FHDTV20A powers up, backlight on, sound works, buttons work, no pict

jeez i dont even see how that tag is related to that chip...

what are we looking for again?

[triplefour]

Re: VIZIO V037L FHDTV20A powers up, backlight on, sound works, buttons work, no pict

we're trying to figure out why j30 is zero. it should be 12v, right?

[budm]

Re: VIZIO V037L FHDTV20A powers up, backlight on, sound works, buttons work, no pict

Yes, there is a MOSFET some where that is bad or it is not turned on, 12V will go into one pin of the MOSFET and comes out on another pin when the Gate is driven by the processor on the main board. We are woking blind right now without the diagram, that is why using Ohm meter is the only way to find out where that pin 30 is connected to. You are doing the resistance testing with TV unplugged, right?

[triplefour]

Re: VIZIO V037L FHDTV20A powers up, backlight on, sound works, buttons work, no pict

yes tv is unplugged for resistances, and turned on for voltages