Vizio Sound Bar - Main Circut Board ( Is ruined ? ) Help

[squarethumps]

Hello All,

First time poster here. Absolute amatuer when it comes to EE, experience with electronics, understands basic stuffs.

I have a VIZIO Sound Bar which will only stay powered on for a few seconds. It seems like it is a heat issue of some sort, as a guess, having some previous experience with power supplies with bad capacitors. Once I turn the unit on, it takes no more than 20 seconds before I hear a 'pop' and it shuts off. I can turn the power swtich off and unplug it for a few minutes and then I can power it up again, but only for a few seconds; less this time.

I took the bar apart and looked at the main board. Please have a look at all the pictures here at this site :
http://s1335.photobucket.com/user/squarethumps/library/VIZIO sound bar?sort=3&page=1


The first thing I noticed was this chip that seemed to have some corrosion in the lower left. There are other pictures of ( capacitors?) which seem to show the (glue?) that was put on very slopy or something is leaking out of them ? If something is leaking it seems odd to me that there are various components that would appear to be leaking the same stuff, which is why I speculate it's some sort of thermal glue.

There was also a sort of white powdery film on the back side of this board which I think you can see in one of the pictures. The chip that really looks bad is the one in the following picutre.


but truthfully I've seen circuts that were worse looking that still functioned. I'm hoping to get any sort of advice on what went wrong with this board and what you can tell from the pictures, and is there any hope to repair it.

Any and all help is always greatly appreciated.

 

[davenn]

Hi
welcome to the forums

the brown stuff is just glue holding the blue cased crystal steady
This stops a problem called "microphonics" in oscillator circuits

the glue around the capacitor and those 2 inductors is because they are large and heavier components
and its purely to hold them in place

I dont see any obvuious faults with any components in any of the pix

Dave

 

[squarethumps]

Thanks for the response.

1. I re-read my post from last night. Please forgive me for the improper grammar and mis-spellings ( I'll correct those ), I must have been more tired than I thought.

2. If there is nothing obvious with the circuits, ( even that one chip ? That's not corrosion on that chip ? ) then does anyone have any speculation on why the unit might shut off after just a few seconds? The light stays on on the power supply, which is inline on the cord.
The capacitors appear to be ok. The ones that I've seen in the past that were bad were domed on the top, though I know that they can be faulty without this symptom.

 

[jcurrie]

if you have a thermal falure first thing do you feel confedent to fire it up with cover off, if so get a can of freeze mist (think its still out there if not it was just Co2) then after falure start spraying the board at one side and go till thing works again that will be your bad spot
jcurrie

 

[squarethumps]

hummm.. ok .. that is an approach I hadn't thought about. I will try to get a can of that and see if there in an effect.

No, though, I'm not 100% convinced it is a heat issue, but I can't imagine what else could explain it ?

speculations?

 

[davenn]

The capacitors appear to be ok. The ones that I've seen in the past that were bad were domed on the top, though I know that they can be faulty without this symptom.

electro caps cap fail before they start bulging. And electro's are the most unreliable of componments. If you do decide to replace them, be really careful as you unsolder them, you will have a good chance of damaging the fine tracks of the circuit board

Dave

 

[The_Penguin]

IMHO that glue was probably not that colour when the unit was made.
Some glues change with heat/age and when they do they start to conduct.

I had a device recently with conductive glue (monitor or power supply, I forget) and chipping it off fixed the problem.

I'd carefully remove it and see if that helps.
Also the photo of the back looks like it may have been wet. Any chance of that?

 

[ConradBurke]

This is great! Thanks for the solution. I am very keen to know the answer for this soundbar issue.

 

[dave9]

Generally the thing to do is post high resolution pictures of the front and back of the entire PCB, at a 90' angle and both oriented the same. This lets people start out with a better understanding of what they're dealing with and provides a map for where each zoomed in area is.

I can't advise using photobucket any longer. It is sluggish trying to load ads, then I switched to a different browser and it proceeded to pop up a box full of ads plastered over the pictures themselves, and it won't close, lol. Blocking a half dozen advertising URLs made it work but then only little pics.

Regardless, two common fault areas in a circuit like this are the PSU subsection or the output transistor(s) shorting out, possibly doing so as they warm up. You might disconnect the speakers and measure the output with a multimeter (set to ACV) to see if it stays on not powering a load.

If worst came to worst you might be able to take the analog output from the DAC to a new amp circuit you shoehorn into the sound bar enclosure, maybe even power it via the same PSU since it will have surplus current available if it's not using its own amp to power the speakers. Little ready to roll class D amp boards are available on eBay and elsewhere.

 

[kellys_eye]

<Robin voice> Holy old-thread-resurrection Batman! </Robin voice>

 

[dave9]

lol, somehow I thought I clicked through to this from the Latest Threads side bar.