Vizio 26" LED LCD m260va - No Power

[caphair]

TV has no power at all. Opened it up and visibly saw problem area. An IC on underside of power supply looks to have burnt pretty badly.

Chunk is missing from top I can't make out the number. Also in the general area around it, the components all measured as shorts even the MOSFET (unless measuring mosfets with an ohm meter isn't right procedure?) From gate to source to drain in any variaton read as 0 ohms.

Couple smd resistors also measured as shorts and there's black smoke that makes reading their values hard, but I don't believe they're rated as 0 ohms or used as jumpers. I've included pics, although not the best (cell phone camera) you can clearly see the area.

Do you think it's worth replacing all these components or buying a replacement power supply? I found one for $20 used online

[retiredcaps]

Re: Vizio 26" LED LCD m260va - No Power

Do you think it's worth replacing all these components or buying a replacement power supply? I found one for $20 used online

Tough call. For me personally, I want to learn via troubleshooting and just replace the damaged components. However, if the power supply is $20 total, and given my crappy soldering equipment, I would lean towards the power supply in this situation.

[caphair]

Re: Vizio 26" LED LCD m260va - No Power

Tough call. For me personally, I want to learn via troubleshooting and just replace the damaged components. However, if the power supply is $20 total, and given my crappy soldering equipment, I would lean towards the power supply in this situation.

I completely agree, I also would want to individually replace the suspected components to learn, but since there happens to be more than a couple and the cooked IC making it hard to identify it, I think a working board for $20 seems like a good choice. Plus I'd have this as a spare for the future in case any of the remaining working parts needed to be swapped.

I'm curious, do you have any idea what would have caused so many components to have failed like this? Power surge?

[PlainBill]

Re: Vizio 26" LED LCD m260va - No Power

I'd say it's a no brainer - go with the used power supply. It's fun to spend $5, $10, or even $20 to avoid buying a $100 board. It's not so much fun to spend $20 for parts to avoid buying a $20 board, and even less fun if the replacement parts start spitting smoke and flames.

PlainBill

[caphair]

Re: Vizio 26" LED LCD m260va - No Power

I'd say it's a no brainer - go with the used power supply. It's fun to spend $5, $10, or even $20 to avoid buying a $100 board. It's not so much fun to spend $20 for parts to avoid buying a $20 board, and even less fun if the replacement parts start spitting smoke and flames.

PlainBill

Lol agreed. Do you have any idea what would have caused series of components to fail like that?

[PlainBill]

Re: Vizio 26" LED LCD m260va - No Power

Lol agreed. Do you have any idea what would have caused series of components to fail like that?

It could have been a power surge as you suggested above, or it could have been a lightning strike. However, the most likely cause is a failure in a single component lead to a cascade of damaged components. A failure in the SMPS controller could have led to the power FET being on too long and shorting. Or the power FET could have shorted, sending a surge of current through the current sense resistor, destroying it and taking out the SMPS controller. They try to design the power supply so a cascading failure doesn't occur, but when you are dealing with voltages and currents this high, it's difficult to prevent.

PlainBill

[caphair]

Re: Vizio 26" LED LCD m260va - No Power

Cool thanks for that. Hopefully this type of failure isn't common in these boards. Could a cascading failure like this transfer as far as the main or t-con board?