Vizio VO42L FHDTV10A No Power

[Xecuter]

Hello. I have a problem that I hope someone on this forum can help me with. I have a vizio vo42l that shows no signs of life. The set does not respond when I try to power it on. The vizio logo also doesn't light up at all.

I've tried searching the interwebs for similar symptoms and possible fixes, but yield none.

What is a good start in trying to resolve the issue. If I replace the power supply unit and it turns out that is not the source of the problem, can it too loose its magic smoke for not correctly identifying the root problem?

Is there any other information that I can provide to aid in troubleshooting.

Thanks in advance for any input that you may have.

[selldoor]

Re: Vizio VO42L FHDTV10A No Power

Hello. I have a problem that I hope someone on this forum can help me with. I have a vizio vo42l that shows no signs of life. The set does not respond when I try to power it on. The vizio logo also doesn't light up at all.

I've tried searching the interwebs for similar symptoms and possible fixes, but yield none.

What is a good start in trying to resolve the issue. If I replace the power supply unit and it turns out that is not the source of the problem, can it too loose its magic smoke for not correctly identifying the root problem?

Is there any other information that I can provide to aid in troubleshooting.

Thanks in advance for any input that you may have.

Hi - As a first suggestion you should search this forum for V042L there are a number of posts already. If you read these you will see what is expected of you and may even enable you to fix it.
You will need to provide photos of your boards and some detail of your background and capabilities. What tools do you have - soldering iron multimeter, ESR meter etc.
The information requested will be detailed as you must remember we cannot see what you are doing.

You say "shows no signs of life. The set does not respond when I try to power it on. The vizio logo also doesn't light up at all."

Have you seen it working at some point - how did you come by it?

Is there absolutely NOTHING when you try to switch it on? No sound no hissing - no clicking. No standby light. After it has been "on" for a while does any of it get warm.

If there is none of the above have you tested the plug/ fuse/ cable have you tried it in another power socket.

Where are you based - working at 110Volts or 220Volts. ?

[bbjunkie]

Re: Vizio VO42L FHDTV10A No Power

Is there absolutely NOTHING when you try to switch it on? No sound no hissing - no clicking. No standby light. After it has been "on" for a while does any of it get warm.

It goes without saying don't go feeling for heat around ANY part of the power supply (even heatsinks) when the set is plugged in and switched on as they are usually live.

Also please remember there will be a nasty charge stored in the main capacitor across the input, and if the power supply isn't working properly that could stay there for some time.

Jim

[Xecuter]

Re: Vizio VO42L FHDTV10A No Power

Thank you so much for the responses. I have simple skills: I can do simple soldering and reflow on pcb. I've read that I need to be careful when dealing with capacitors. I only have a simple Harbor Freight digital multimeter but I'm barely learning how to use it.

When I first opened the vo42l, I left it connected for a couple of hours while I analyzed it. Nothing warmed up and all capacitors looked visually sound. I'm not sure what points I should test or how.

I'm not home right now, so when I am I will uploads some pictures and reedit post with views of all the components.

[Xecuter]

Re: Vizio VO42L FHDTV10A No Power

I received the tv for free as I believe It died on the previous owners. I didn't receive much information on it but it seems they tried to get it repaired but I don't know what, if anything, was done to it.

I know I have power in my outlets and the power cord is fine. I also checked the fuse and there is continuity. Beyond this, I don't what to do on my own.

[bbjunkie]

Re: Vizio VO42L FHDTV10A No Power

Congratulations, some excellent quality pics!

I could be wrong, but I think I see scorching around R206 between the heatsink for the rectifier and the one for the chopper transistor.


<Edit> Just checked a pic from djsmith's thread which is also about a VO42L and yes, R206 is definitley toast on your board.

Can you post a pic of the other side of the power supply board?


Jim

[Xecuter]

Re: Vizio VO42L FHDTV10A No Power

Thank you so much. You are very correct. R206 is blown but I can't see the value. If I replace this, are my chances of getting it to power up be good?

Also, I did post a picture of the power supply board bottom. It is the one next to the top view of the power supply in my previous post. Should I post a new one?

[selldoor]

Re: Vizio VO42L FHDTV10A No Power

Can you post a pic of the other side of the power supply board?


Jim

Hi I thought it looked burnt as well- Is Pic 2 the other side.
I struggled with it as it is opposite way round from pic 1 but the 4 solder
blobs in a square coincide and 2 are in line with the hole at the edge of the board.
I also wondered about a cap C103 which looks a bit corroded on the end but
perhaps just the flash?

[bbjunkie]

Re: Vizio VO42L FHDTV10A No Power

sorry, I see it now.. had too many windows open, firefox had hidden it!

Replacing R206 probably wont fix it, i'd guess something else has caused it to burn out in such a dramatic way. I'm still new to this, so i'd not like to hazard a guess. I'm off to find a circuit diagram for the circuit and in the meantime no doubt one of the regulars will be along with their wealth of knowledge.

[bbjunkie]

Re: Vizio VO42L FHDTV10A No Power

Check the switching transistor on the heatsink beside that resistor, can't see the number on the board. Looks like that could be a possible cause, one leg of the resistor goes there, the other seems to go to IC201.

I have located a manual, downloading it now (slowly)

Dont forget to discharge C10 before proceeding with any diagnostics or repair

[Xecuter]

Re: Vizio VO42L FHDTV10A No Power

@celldoor - I checked cap c103 and it seems visually fine. Light is affecting its look I think.

@bbjunkie - Yes, one of the legs of the transistor goes to ic201. I don't know how to test it. Can I use my DMM to test it?

Also, I noticed R202 has a weird black spot. Is it busted also?

[bbjunkie]

Re: Vizio VO42L FHDTV10A No Power

Good spotting! certainly does look like it has popped, it's also connected to our suspect switching transistor.

Ok, you can check the transistor with your DMM - what is the number on it (the transistor)?

[Xecuter]

Re: Vizio VO42L FHDTV10A No Power

The numbers that I see on it are GBU806.

[bbjunkie]

Re: Vizio VO42L FHDTV10A No Power

no, the one close to r222 - that is the bridge rectifier you have looked at

[Xecuter]

Re: Vizio VO42L FHDTV10A No Power

Oops! Sorry.

I'm having a hard time reading it. I think it's P9NK70ZFP GK1YH 6V CHN 752.

[bbjunkie]

Re: Vizio VO42L FHDTV10A No Power

Ok, this is a 700v power MOSFET - datasheet available at http://pdf1.alldatasheet.com/datashe...P9NK70ZFP.html

Check it for shorts using your DMM on the ohms setting you don't want to see anything lower than about 30 ohms on any combination of pins.

There was no need to remove the transistor from the circuit to test it, though now you have it out don't bother putting it back in just yet.

[Xecuter]

Re: Vizio VO42L FHDTV10A No Power

I get the same read out in every test lead combination.

[bbjunkie]

Re: Vizio VO42L FHDTV10A No Power

The MOSFET is dead, and as a result has taken the resistors with it.

Hopefully the regulars will be here soon to point you in the right direction from here - I'm not sure if replacing these three components will be enough, or if the MOSFET may have been taken out by the controller IC, or vice versa.

I see Retiredcaps posting in other threads, perhaps he will post here soon, if not im sure Plainbill or tom66 wont be far behind

[retiredcaps]

Re: Vizio VO42L FHDTV10A No Power

I get the same read out in every test lead combination.

Shorted for sure. It is bad.

[selldoor]

Re: Vizio VO42L FHDTV10A No Power

While youve got your meter handy you can check F1 Fuse - looks jolly black perhaps its meant to be? Its between the metal plate and the brown cable on the left hand side. There may be other fuses as well Ill have a look around the board.

Sorry No brown cable on your pic - (I had two open) - You just have the Pin - Marked L