Vizio vw42lfhdtv

[fixerupper75]

I have a vizio vw42lfhdtv and it only has an amber light. It does not change to white when I press the power button or use the remote. The only voltage i have is stndby 5v. No p_s on, 12v or 24v. Any suggestions????

[MagicSmoke]

Re: Vizio vw42lfhdtv

It could be an eeprom problem, this is a known flaw with many options for repair.

Or it could be a bad voltage regulator or other component on the main board.

I have a Vizio 32" that has a bad dc/dc converter on it, causing it not to power on.

You can jumper 5.3v stby to pson to check 12v & 24v. I would disconnect mainboard first.

[fixerupper75]

Re: Vizio vw42lfhdtv

Is there a way to check the eeprom? I will post pictures later.

[nomoresonys]

Re: Vizio vw42lfhdtv

It could be an eeprom problem, this is a known flaw with many options for repair.

Or it could be a bad voltage regulator or other component on the main board.

I have a Vizio 32" that has a bad dc/dc converter on it, causing it not to power on.

You can jumper 5.3v stby to pson to check 12v & 24v. I would disconnect mainboard first.

for sure, that lets you test for 12 and 24v, if its there, it might not be power supply, if no 12 and 24, could be power supply, careful when working with power supply, HIGH VOLTAGE, on primary side.

[nomoresonys]

Re: Vizio vw42lfhdtv

Is there a way to check the eeprom? I will post pictures later.

if you mean eeprom on mainboard, your getting ahead of yourself, if you don't get the proper voltages from the power supply, the tv will notwork right, power comes in to power supply, then goes out to other boards.

[nomoresonys]

Re: Vizio vw42lfhdtv

read the first stickie post, in this category, by budm, how lcd tvs work.

[fixerupper75]

Re: Vizio vw42lfhdtv

I thought it stated that the 5v stndby trigger the 5v p_s on which in turns on 12v and 24v. But I will read again.

[budm]

Re: Vizio vw42lfhdtv

At this point, check the voltages of the regulator IC's on the main board.
Report the readings in the format we show in this thread:
https://www.badcaps.net/forum/showth...999#post300999

[fixerupper75]

Re: Vizio vw42lfhdtv




Here are couple of pictures. I did find one cap with a bulge. Will check the voltage regs. later.

[budm]

Re: Vizio vw42lfhdtv

That is a good start.
To remove that cap, you will use flux and ADD more solder to the two legs using at least 40W iron, 60W is preferred, with wide tip, move the tip back and forth between the two leg while pulling on the cap to get it off the board.

[MagicSmoke]

Re: Vizio vw42lfhdtv

Never seen a cap on main board bulge. Definitely bad, may be others.

Edit...It is next to a VR so it may have over-volted

[budm]

Re: Vizio vw42lfhdtv

That cap looks to be for the output filter for that U20 ADJ regulator IC.
If the cap is not shorted out then you can solder in another cap in parallel to test and see if you will get PS_ON.
You need to see what DCV you have on the ADJ/GND left PIN, output center pin, and input right pin.

[fixerupper75]

Re: Vizio vw42lfhdtv

Hey guys thanks for your help!!!! I will replace and check the Voltage on the u20 reg and report my finding tomorrow.

[budm]

Re: Vizio vw42lfhdtv

Check the voltage before and after.

[fixerupper75]

Re: Vizio vw42lfhdtv

right pin 3.3 volts
center pin 1.8v
left pin .5v
These are voltages to U20 and I also replaced the bulged cap.

[fixerupper75]

Re: Vizio vw42lfhdtv

for sure, that lets you test for 12 and 24v, if its there, it might not be power supply, if no 12 and 24, could be power supply, careful when working with power supply, HIGH VOLTAGE, on primary side.

I jump the p_s on and got 12v and 24v but didn't get a blue screen or was I suppose to get a blue screen.

[fixerupper75]

Re: Vizio vw42lfhdtv

Voltage reg. Reading
U15
r/s 5
cntr 3.3
l/s 2

U17
r/s 5
cntr 3.3
l/s 2

U19
r/s 5
cntr 2.5
l/s 1.25

U21
r/s 2.5
cntr 1.25
l/s 0

U22
r/s 5
cntr 3.3
l/s 2.0

U44
r/s 0
cntr 0
l/s 0

[nomoresonys]

Re: Vizio vw42lfhdtv

ok, making progress, if you unplug ps-on connector from power supply to mainboard, do the backlights come on?

[fixerupper75]

Re: Vizio vw42lfhdtv

ok, making progress, if you unplug ps-on connector from power supply to mainboard, do the backlights come on?

No the backlights do not come on. But I do have 24v on the inverter boards

[nomoresonys]

Re: Vizio vw42lfhdtv

I'm no expert, but that could point to maybe something wrong with inverter.