Vizio VW42L FHDTV10A will not turn on without unplugging and plugging TV back in

[ken_taz]

Re: Vizio VW42L FHDTV10A will not turn on without unplugging and plugging TV back in

Wonder if this mainboard is a match? they want 45 bucks, seems a little steep, wonder if they would take less. https://www.ebay.com/itm/Vizio-VW42L...ty!43616!US!-1

None of the numbers match. The numbers on the sticker are different as well as the imprinted number on the board itself. But thanks!

[nomoresonys]

Re: Vizio VW42L FHDTV10A will not turn on without unplugging and plugging TV back in

Wonder if this mainboard is a match? they want 45 bucks, seems a little steep, wonder if they would take less. https://www.ebay.com/itm/Vizio-VW42L...ty!43616!US!-1

[ken_taz]

Re: Vizio VW42L FHDTV10A will not turn on without unplugging and plugging TV back in

Different panel, When thes sets are built all the parts are dropped off in the middle of the street during the day, people from both sides of the street grab the parts and assemble them at night, in the morning the mfg picks up the assembled tvs.

I love this!!!

[ken_taz]

Re: Vizio VW42L FHDTV10A will not turn on without unplugging and plugging TV back in

"u43 is the ic associated with the vga input and transistors Q27- Q30" well maybe check those transistors with your meter.

Okay, after days of testing with heating that small area, I have really not come to any conclusions.
I would plug the TV in and try to turn it on first thing in the morning without heating anything. It would turn on with back light on, but it would shut off after being on for a few seconds.
I would turn it back on and sometimes it would stay on with just the back light on and nothing else. I would also have to unplug the TV to turn it off at this point. Other times it would turn on normally with picture, but after a few seconds it would get those vertical lines and loud buzzing thru the speakers.
I would then heat the area mentioned and the TV would turn on normally and stay on. I left it on for over an hour to see if it would shut off and it didn't. I did this for 2 days to make sure of the pattern.
This morning, I heated the area before I turned it on. It turned on the very first time and stayed on.

Could this U43 VGA ic be the problem? (actually RGB on this TV I believe) When I put the TV input to RGB it tells me "No signal or input voltage. TV will be shut down" and then the TV shuts off.

Also the transistors we were talking about, Q27-Q30, should include Q49 because it is part of the circuit for opcrtl 5 as you can see in the picture below. Can I test the transistors without removing them first?

I've taken a couple pictures of these transistors and VGA ic as well. Holy crap, these things are tiny! I'm having some trouble matching new transistors and the VGA ic by the markings on them. Well, the transistors anyway.

[nomoresonys]

Re: Vizio VW42L FHDTV10A will not turn on without unplugging and plugging TV back in

^lmao^

[R_J]

Re: Vizio VW42L FHDTV10A will not turn on without unplugging and plugging TV back in

Different panel, When thes sets are built all the parts are dropped off in the middle of the street during the day, people from both sides of the street grab the parts and assemble them at night, in the morning the mfg picks up the assembled tvs.

[ivtec]

Re: Vizio VW42L FHDTV10A will not turn on without unplugging and plugging TV back in

Ok budm, no problem. It goes to the manual control panel. I will work on replacing those caps. Thank you!

Hi guys sorry to butt in but i check this Vizio has only 1 Inverter board?, mine same modle# has 2 inverters ,master and slave ?don't understand,can someone shad some light ,

[R_J]

Re: Vizio VW42L FHDTV10A will not turn on without unplugging and plugging TV back in

I suspect the MT5381 ic might be different on this board but it is likley the ic under the heatsink? If those caps go bad on the regulator outputs, the regulators start to oscillate and create a lot of noise on there output, this can cause problems with the data in the ic they supply. especially when you are dealing with 3.3v or1.25 volts.
replacing CE17 and CE13 cured some of the problems did'nt they?

As for the Q27-Q30 they seem to be just drivers so I doubt they are the problem,thats why it seemed strange that heating in that area seemed to fix the problem.

$6.00 a cap from ratshack. you could have ordered 50 and had them shipped from digikey for less, and likely just as fast. I have had parts shipped from digikey to Canada for $8.00 and they arrived next day.

[nomoresonys]

Re: Vizio VW42L FHDTV10A will not turn on without unplugging and plugging TV back in

I replaced the 3 caps in the section that was heated. It still has the same problem. I should have invested in an ESR meter. Chasing these caps blindly surely isn't the way to go, lol. My own fault. I spent $6 a piece for the 220uf 16v caps at Radio Shack.

6 bucks each, OUCH.

[ken_taz]

Re: Vizio VW42L FHDTV10A will not turn on without unplugging and plugging TV back in

I ment u43 is the ic associated with the vga input and transistors Q27- Q30 that are in that area are associated with opctrl lines that drive white and amber led's.

It seems a lot of control comes from the MT5381 ic, so there might be poor filtering on the supplies to that ic like CE11, CE7, CE21

If there is a problem with the transistors Q27 - Q30, will it cause the TV to not operate correctly, or do they just drive the amber and white led's?

What is the MT5381 ic?

Thanks, R_J

[ken_taz]

Re: Vizio VW42L FHDTV10A will not turn on without unplugging and plugging TV back in

You have 3 lytic caps in that section, try replacing them.

I replaced the 3 caps in the section that was heated. It still has the same problem. I should have invested in an ESR meter. Chasing these caps blindly surely isn't the way to go, lol. My own fault. I spent $6 a piece for the 220uf 16v caps at Radio Shack.

[R_J]

Re: Vizio VW42L FHDTV10A will not turn on without unplugging and plugging TV back in

It seems a lot of control comes from the MT5381 ic, so there might be poor filtering on the supplies to that ic like CE11, CE7, CE21

[nomoresonys]

Re: Vizio VW42L FHDTV10A will not turn on without unplugging and plugging TV back in

"u43 is the ic associated with the vga input and transistors Q27- Q30" well maybe check those transistors with your meter.

[ken_taz]

Re: Vizio VW42L FHDTV10A will not turn on without unplugging and plugging TV back in

Oh ok, now I understand what you are saying. I'm sorry, I didn't mean that statement the way it sounded. I was just trying to make sure that I understood what you were saying. I do appreciate your input very much and do appreciate your time and knowledge.
Thank you!

[R_J]

Re: Vizio VW42L FHDTV10A will not turn on without unplugging and plugging TV back in

I guess I should not have given you a page number and had you search through all 177 pages to find the circuit
Opctrl are control lines, they have numbers to tell them apart, in this case opctrl4 and optrol5 are in the area you were heating.

[ken_taz]

Re: Vizio VW42L FHDTV10A will not turn on without unplugging and plugging TV back in

Yes, it is my post. I just don't understand what you are telling me.
The parentheses around (page 160) and (4 or 5) make the whole sentence very confusing to read. What is the (4 or 5) anyway? The sentence just needs to be rewritten.
Thank you for the schematic.

[R_J]

Re: Vizio VW42L FHDTV10A will not turn on without unplugging and plugging TV back in

Is'nt that your post in #35? you outlined part of the board with a red line and said you heated that area. I just thought a schematic might help.
I ment u43 is the ic associated with the vga input and transistors Q27- Q30 that are in that area are associated with opctrl lines that drive white and amber led's.
These components are in that area that you said you applied heat and the tv works
The schematic might not be identical but might help.

[ken_taz]

Re: Vizio VW42L FHDTV10A will not turn on without unplugging and plugging TV back in

This manual has similar parts in that area, on page 164 are the transistors U43 (page 160) is vga control ic. Looks like your problem could be associated with OPCTRL (4 or 5) lines

I'm sorry R_J, but I don't understand exactly what you're trying to tell me here
"on page 164 are the transistors U43 (page 160) is vga control ic. Looks like your problem could be associated with OPCTRL (4 or 5) lines"

[R_J]

Re: Vizio VW42L FHDTV10A will not turn on without unplugging and plugging TV back in

This manual has similar parts in that area, on page 164 are the transistors U43 (page 160) is vga control ic. Looks like your problem could be associated with OPCTRL (4 or 5) lines

[ken_taz]

Re: Vizio VW42L FHDTV10A will not turn on without unplugging and plugging TV back in

Good idea. I was trying to think of a way to pinpoint it even better without ruining the cap in the process. Hair dryers are a good starting point but when it comes to really heating a tiny area....not so much. Thanks!