Vizio VW42L problems

[chopsawkev]

greetings,

I have Vizio VW42l that my friend was throwing out so I am making an attempt to repair it for the me and the lady. mostly of my electrical knowledge comes from repairing motorcycle's (what I do for a living) so I apologize in advance If I ask a bunch of newbie questions.

Any who, I've been reading a lot about these sets lately, most importantly these 3 threads on this forum.

https://www.badcaps.net/forum/showthread.php?t=19604
https://www.badcaps.net/forum/showth...ht=vizio+vw42l
https://www.badcaps.net/forum/showth...ighlight=vizio

I'll start with how the set behaves, then into what work ive done so far, then some more troubleshooting then a whole bunch of questions.

If you turn the set on, the amber Vizio light goes white for about 90 seconds, then goes back to amber. no backlight. im assuming no sound.

so when i took the back off and started to dig in, I noticed that all of the caps on both inverter boards (4 total) were blown. I've replaced all of them. no change.

In standby mode, the standby fuse shows 5v. turn it on, the power fuse on the main board jumps up (i see maybe 5 volts at the most) and then it slowly trails off until it returns to standby.

moving ahead ive checked the low voltage regulators and here are my results:

U2
AMC1117
F0734F
PIN1 .1347v
PIN2 .2185v
PIN3 .1129v

U7
AMC1117
F0734F
PIN1 0.0002V
PIN2 0.0002V
PIN3 0.0028V

U8
AMC1117
F0734F
PIN1 2.055V
PIN2 3.299V
PIN3 5.17V

U9
K1117S15
745
PIN1 0.0002V
PIN2 0.0002V
PIN3 0.0028V

U33
AMC1117
F0734F
PIN1 .0018V
PIN2 .0028V
PIN3 .1129V


I'm not really sure where to go from here ... im guessing that the unit not powering up completely is a problem and not letting me test the low voltage regulators properly. I want to check the power supply, but im not really sure how to go about doing that, any pointers?

thanks a lot in advance!

[chopsawkev]

Re: Vizio VW42L problems

and just a heads up, both of the inverters are rev 1.3.

[selldoor]

Re: Vizio VW42L problems

you are right - only u8 appears to be anywhere near correct output.

Welcome to the forum-
We can help a lot more if you please post good clear pictures of the whole chassis, and then pictures of each board, front and back (in the same orientation) and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

Please do not post inline and offsite as they slow down the loading of pages.

Examples of what is needed

https://www.badcaps.net/forum/attach...7&d=1280167246

https://www.badcaps.net/forum/attach...6&d=1280167246

https://www.badcaps.net/forum/attach...4&d=1280167246



Tried holding the power button in 30 seconds?

[multimeter]

Re: Vizio VW42L problems

all the rest apart from u8 is faulty, 1117's prone to fail 5v-3.3 ?

what brand of caps where old ones replaced with?

[tom66]

Re: Vizio VW42L problems

No, the rest have no input voltage, so no output voltage. Similar principle as automotive regulator...

[chopsawkev]

Re: Vizio VW42L problems

ill post pics of the board later tonight, i replaced them with ones from digikey, ones that i think tom66 here recommended in another post.

[chopsawkev]

Re: Vizio VW42L problems

so here are the best photos i could get, thanks for all the help.

if i hold the power button in, it cycles from amber to white every 9 or so seconds. when the white comes on, its bright, and then slowly fades.

[chopsawkev]

Re: Vizio VW42L problems

sorry i posted two pictures of the slave, here is the master.

also you can see the caps that I replaced on the master and slave unit.

[selldoor]

Re: Vizio VW42L problems

POWER OFF
In Pic 8 under the middle top connector there are two white smd fuses - meter on ohms can you test them.

[chopsawkev]

Re: Vizio VW42L problems

im getting 0 ohms on both. I get continuity between both ends of the fuse.

[chopsawkev]

Re: Vizio VW42L problems

same goes for the barrel fuse (I think that's what it is) in pic 4 on the left.

[martyparish]

Re: Vizio VW42L problems

I see SMD fuses on the inverters as well. You should check them.

Also, may I suggest stepping back a minute to have a look at the PSU? Have you monitored the voltages on all pins of the connectors while you turn it on?

PSU sounds like a possibility here. When you say they inverter caps were blown, did you visually see bloating or did you test them? (what about the caps on the PSU?)

[chopsawkev]

Re: Vizio VW42L problems

visual bloating on the caps on the inverters.

im not getting 24v or 12v on any of the pins the PSU. however, the set won't stay on long enough for me to get a good measurement. I agree that the something is wrong on the PSU, im just not sure on what im exactly looking at/for. how do i check caps besides visually?

when the power button is pressed the voltage spikes and then quickly trails off ... the most I see with my multi is 3 to 5 volts peak.

[chopsawkev]

Re: Vizio VW42L problems

the smd on the interverters are fine, and just to idiot check myself, im getting 110ish volts AC right up into the PSU.

[martyparish]

Re: Vizio VW42L problems

You said the VIZIO logo stays white for 90 secs, that should be enough time to monitor the voltages on the connectors. Of course, you will have to power up the set anew each time you retest since you can't so them all in 90 secs.

Also check the BL_ON and PS_ON pins, and it's important to see what they read "while" it's trying to power up.

You can also try disconnecting both connectors that feed the inverters from the PSU(with power off)

Then, try to power up the set and see if it will stay on. If it does, you have narrowed it down somewhat.

[chopsawkev]

Re: Vizio VW42L problems

ok now we are getting somewhere ...

I dont have a b/l pin.

with the inverters unplugged, the tv still stays on for about 90 seconds before going back to standby.

If I check voltage at the main board (with the inverters unplugged) i'm seeing what I guess would be normal voltage. here is the run down.


Ps_on
p1 - 3.1v

12v
p2 - 11.6v
p3 - 11.6v
p4 - 11.6v

sgrd
p5 - 11.4mv
p6 - 11.4mv
p7 - 11.4mv
p8 - 11.4mv

5vsb
p9 - 5.1v
p10 - 5.1v
p11 - 5.1v

A,B
p12 - 2.9v
p13 - 5.1v

now if i plug the inverters in, things get all goofy. with the inverters plugged in I see:

Ps_on
p1 - 3.1v

12v
p2 - 1v
p3 - 1v
p4 - 1v

all 3 pins start at 1v and then slowly reduces in voltage to 0 and then the set switches to standby

sgrd
p5 - 11.4mv
p6 - 11.4mv
p7 - 11.4mv
p8 - 11.4mv

5vsb
p9 - 5.1v
p10 - 5.1v
p11 - 5.1v

A,B
p12 - 1.4v
p13 - 2.8v

also notice here that pins A and B are almost halved in voltage.

i bet if i check the low voltage regulators with the inverters unplugged ill get a more accurate reading on them.

[chopsawkev]

Re: Vizio VW42L problems

So im getting continuity to ground on all the the 24v pins on the inverters?

*edit* i get this if the slave is hooked up, not the master. if just the master is hooked up, no continuity to ground on the 24v pins. problem must be on the slave then?

[martyparish]

Re: Vizio VW42L problems

Alright, this may sound crazy, but you can try taking a hair dryer and heating up the PSU components for a bit, then try power up. Focus the heat on the secondary side when you heat it up. Don't melt anything, just get 'em toasty

Also, I believe either A or B is going to be the backlight-on pin.

Try the heat test and let us know if anything changes. There is another test that can help you rule out or identify main board.

If you haven't already, please read budm's LCD troubleshooting guide. You will see it at the top of the TV forum as a sticky.

[vinceroger69]

Re: Vizio VW42L problems

whats the slave transformer part numbers i would test them next

[chopsawkev]

Re: Vizio VW42L problems

the hairdyer trick yielded no results except for making my apartment smell like my girlfriend just got out of the shower.

vinceroger, what part is the slave transformer? could you point it out?

all of the 24v pins are grounded on the slave side. I don't know what that means, but just thought maybe that doesnt seem right. if I fire the tv out without the slave plugged in, I get a blue LED on the master inverter for a couple seconds.