Vizio VL470m Blinking vizio, wont power on.

[ivoh]

Hi guys im new here, But im hoping you can help me. I picked up a vl470m today for 20$ and im hoping you can help me fix it. when plugged in the orange standby light comes on and when i press the power button the vizio light turns white and starts blinking slowly (like every 1.5 sec) no backlight or picture/sound. Ive checked the PSU, the 5v are good and the 12v come up as expected when powered on. Looking at the mainboard, the regulators described in the service manual all have the proper voltage, no blown fuses, etc. near the display driver, there is a chip which is a gamma driver? and it gets no power when the tv is turned on and it along with 2 more chips have markings on them(maybe it was already taken to a repair shop?) there is also a voltage regulator? near there which also gets no power. i dont know if they are supposed to get power. Any ideas guys? thanks!

[ivoh]

Re: Vizio VL470m Blinking vizio, wont power on.

pictures attached. The marked chips can be seen in pic 3.

[ivoh]

Re: Vizio VL470m Blinking vizio, wont power on.

could it be faulty solder on the main cpu? it is BGA. my last resort would be to try and reflow it to see if that changes anything. Also there is an led? on the underside of the board does not light up, im not sure if its supposed to

[Dgtech]

Re: Vizio VL470m Blinking vizio, wont power on.

How about pics of the inverter boards

[ivoh]

Re: Vizio VL470m Blinking vizio, wont power on.

How about pics of the inverter boards

power and inverter are one piece. the main board is getting all proper voltages. could a bad inverter keep it from starting? should i try turning it on with the inverter control cable unplugged?

[ivoh]

Re: Vizio VL470m Blinking vizio, wont power on.

I checked the inv_on and its at 0v. so the inverter is not getting turned on. mainboard is the likely culprit. also i noticed that when the set is first plugged in the 12v turns on for about one second then goes back to standby.i am leaning towards reflowing the cpu. anyone have anything else i could try before reflowing?

[budm]

Re: Vizio VL470m Blinking vizio, wont power on.

I agree that you do have main board problem, but what is the cause of the problem, I do not know.

[ivoh]

Re: Vizio VL470m Blinking vizio, wont power on.

I tried a very gentle reflow with a heat gun and there is no change. anyone who can help me do a component repair on the mainboard? maybe its an eprom issue?

[bammbammfran]

Re: Vizio VL470m Blinking vizio, wont power on.

Does the on/off pin have power and does it change when you push the power button.
If it has power, you can try jumping that on/off power over to the backlight on to see if they turn on

[ivoh]

Re: Vizio VL470m Blinking vizio, wont power on.

Does the on/off pin have power and does it change when you push the power button.
If it has power, you can try jumping that on/off power over to the backlight on to see if they turn on

will try that. and i think this is the problem area of the board as the chips here are marked and the voltage regulator here gets no input voltage (it starts at 0 and slowly rises to .4-.5 of a volt. im not sure what tu2 is( i think mofsets?). but tu5 gets no power also. ive marked where there is continuity with the different colors. VCC2 has continuity with a few pins which are connected together and i believe are the supply voltage for the lcd panel. all these pins have less than .5 v when powered on. now how to figure out what supplies power to this area of the board?

[ivoh]

Re: Vizio VL470m Blinking vizio, wont power on.

i traced it back and the power supply for that stuff is turned on and off via a mofset and a transistor and the transistor leads directly to the cpu. so the cpu is not turning on that part of the board for some reason. software bug? or just a dead cpu?

[bammbammfran]

Re: Vizio VL470m Blinking vizio, wont power on.

i traced it back and the power supply for that stuff is turned on and off via a mofset and a transistor and the transistor leads directly to the cpu. so the cpu is not turning on that part of the board for some reason. software bug? or just a dead cpu?

might also be no power to the cpu ?
Not all voltage regulators turn on with basic power on
some turn on once an input is detected.

It looks like there are a few other voltage regulators all over the board that could be checked for possible issues
looks like 3 are large ones, and there may be more of the smaller style like you pointed out

[ivoh]

Re: Vizio VL470m Blinking vizio, wont power on.

might also be no power to the cpu ?
Not all voltage regulators turn on with basic power on
some turn on once an input is detected.

It looks like there are a few other voltage regulators all over the board that could be checked for possible issues
looks like 3 are large ones, and there may be more of the smaller style like you pointed out

ive checked all regulators i could find. ive eliminated reflow. so im assuming its an eprom issue. on the eprom nearest the cpu, there is voltage on one of the terminals for only a second after power on and then for one more second and it stops till i unplug it. i guess that voltage is the cpu trying to read the eprom and retrying and then giving up?

[ivoh]

Re: Vizio VL470m Blinking vizio, wont power on.

Ok guys new question. since the main baord is dead, and i have a e370vl. the e370vl mainboard is very similar to the vl470m. could i use the mainboard from the 370 to test the 470 lcd panel. are the pinouts of their lvds connectors the same? thanks!!!

[Dgtech]

Re: Vizio VL470m Blinking vizio, wont power on.

I advise against it. I cant tell you why though. All the voltages should be lower voltages coming from it. To keep from damaging anything , the voltages going into it is what has to match up for the most part. If you do try this, I'd like to know the result. I find it much easier learning from other people's ballzy moves.

There really is no way to guarantee it will work without comparing pinouts of both boards in a schematic.

[ivoh]

Re: Vizio VL470m Blinking vizio, wont power on.

I advise against it. I cant tell you why though. All the voltages should be lower voltages coming from it. To keep from damaging anything , the voltages going into it is what has to match up for the most part. If you do try this, I'd like to know the result. I find it much easier learning from other people's ballzy moves.

There really is no way to guarantee it will work without comparing pinouts of both boards in a schematic.

the issue would be if all the pins are in the same location. most importantly the power ones. i did some basic comparisons tracing and comparing pins on the different boards and to me it seems that the power pins are in different locations. so i think itd be a no go. also the panels are different brands, so that cant help either.