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Old 09-21-2013, 07:59 AM   #1
tuantrn7
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Default Vizio E421VA No Sound Through Speakers

Hello everyone,

I have an out-of-warranty Vizio E421VA that is not getting sound through the built-in speakers. The only sound that comes out is a very subtle high-pitched noise that disappears when the volume is turned all the way down or on mute. That high-pitched noise is constant when the volume is on, no matter what is playing on the TV. I tinkered with all the settings I could on the TV (turned speakers on/off, changed the speaker balance to left/right, turned off surround sound and the other special sound features). I've also tried resetting the TV to factory setting a couple of times and did some other suggestions that worked for other people like unplugging the power and holding down the power button on the TV, which I guess is another way to reset it. Also, none of the wiring inside the TV appear loose to me -- I unplugged/plugged some of them to make sure.

I've opened the TV and thought I could try testing the speakers with a AA battery to see if it makes any static, and it does, so it seems the speakers themselves are probably working. I've tried playing music from my laptop with it connected to the TV via an AV-headphone cable without success. After reading someone's suggestion, I tried connecting a soundbar to the TV via the optical sound jack and that DOES work -- sound from the TV comes out of the soundbar without any problem. After researching online, a lot of things are pointing to the sound amplifier/IC? I don't have much experience with fixing TVs but would like to try to fix this myself, if possible. However, I am having trouble finding any resource that points me to where the sound circuitry is located on the board -- I'd like to try to replace that specific chip/SMD/IC if I can. I'm hoping to find that the part is burnt or getting too hot or maybe has "cold solder joints." Nothing appears burnt from what I can see and none of the caps appear bulging, but there are a couple of heatsinks that may be hiding something.

At the very top edge of the board in the picture, 1/3 of the way from the right (RED ARROW), there is a white connector where the speaker wires connect. There is a heatsink (YELLOW ARROW) soldered into the board via 2 metal rods. Could the sound IC be located under that heatsink?

I apologize for my ignorance with TV circuitry but would like to fix my TV sound and appreciate any help/direction with this. (Please be as specific as you can, even better if you can circle the location on the picture if you can). Thanks for any help!

P.S. The soundbar is borrowed and not mine, so I'd like to avoid buying a soundbar if it can be helped. I'm not much of a sound person and the native sound through the built-in speakers is adequate for me (and it's more convenient to adjust volume with the TV remote rather than having a separate remote for the sound). It'll also be gratifying if I can get it working again -- thinking of this as a personal project. =)
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Old 09-21-2013, 08:12 AM   #2
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Default Re: Vizio E421VA No Sound Through Speakers

Does this TV have a headphone output? If so, does that work?

The sound IC would be under that heatsink. It is efficient class D type (compared to conventional class AB) so does not require much heatsinking, many devices nowadays don't even have that heatsink.
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Last edited by tom66; 09-21-2013 at 08:13 AM..
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Old 09-21-2013, 09:00 AM   #3
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Default Re: Vizio E421VA No Sound Through Speakers

Thanks for your quick reply/helpful information. Unfortunately it does not have a headphone output. Would the headphone output hypothetically help to differentiate anything further (for my own knowledge)? Luckily the optical audio output has been working still.

The underside of that heatsink location does not have prongs going through the board (other than the 2 prongs from the heatsink itself), so it's looking probably like a surface mounted audio IC?
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Old 09-21-2013, 09:03 AM   #4
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Default Re: Vizio E421VA No Sound Through Speakers

I'd guess so. If you can't get the heatsink off, there's not much you'll be able to do to repair it.
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Old 09-21-2013, 09:16 AM   #5
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Default Re: Vizio E421VA No Sound Through Speakers

I have this exact same TV, (fantastic model btw, Vizio's current 42" selection doesn't go above 60 HZ) and I HAD this exact same issue about a month ago

Took it to a TV repair shop and they said it was the main board and wanted $320 to fix it. Bought the mainboard on EBay and did the work myself for $90, now it works like a charm.

Incidentally that was my inspiration for buying TVs on CL and scrapping them for parts on E-bay....which was my inspiration for joining this forum.....which was my inspiration to reply to this thread

Edit-

Good luck finding the individual component that is causing this, I still have my old Main Board and would love to know the answer as well so I can fix it, then resell the one I bought on E-bay. It took me days to find anywhere that had this Main Board in stock. Let me know if you want any pics of my main board that's broken and the one that's working...maybe some kind of visual comparison would help? Doubfult, but figured I'd offer.

Last edited by Dangermoose007; 09-21-2013 at 09:24 AM.. Reason: Additional Info
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Old 09-21-2013, 12:22 PM   #6
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Default Re: Vizio E421VA No Sound Through Speakers

Hopefully I'll be able to get the heatsink off without damaging anything.

Haha, that's an awesome emoticon with the beer glasses. $320 is just crazy, glad you were able to fix it for $90. I agree that it is a very good TV; I'll be sure to update as soon as I make any progress with this issue -- I'm excited to give it another look when I get a chance. Thanks for offering the pictures, I'll let you know if I run into anything that needs a possible comparison, though probably hard to compare with pictures unless blatantly obvious.
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Old 09-21-2013, 01:37 PM   #7
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Default Re: Vizio E421VA No Sound Through Speakers

Vizio LCDs are known to have lots of main board issues when they fail.
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Old 09-23-2013, 03:18 PM   #8
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Default Re: Vizio E421VA No Sound Through Speakers

Don't know if OP is still planning on trying the repair, but I'm down.

Attached is a pic of the underside of the board where the heatsink is located. Looks like there is a lot of solder that kind of bubbled up. You can't tell too well with the picture, but its very "3-D" in terms of how protruding that mass of solder is.

I'm going to try to De-solder the heatsink, and I'll post more pictures of my progress/epic fail as I go.
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File Type: jpg Board Bubbles.JPG (118.4 KB, 100 views)

Last edited by Dangermoose007; 09-23-2013 at 03:19 PM.. Reason: forgot pic
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Old 09-23-2013, 04:07 PM   #9
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Default Re: Vizio E421VA No Sound Through Speakers

That's awesome, thanks for posting the picture. I am still planning on repairing but won't get a chance to open it up til possibly this weekend. I'll update whenever I can, best of luck in the meantime! Keep us posted.
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Old 09-23-2013, 04:17 PM   #10
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Default Re: Vizio E421VA No Sound Through Speakers

I have ordered a solder sucker on E-Bay, should be here sometime before the weekend. I tried to de-solder without one just by warming up the pins to the heat sink hoping it would melt the solder and I'd be able to pull it out...but for some reason the heat sink seemed to soak up all the heat, and distribute it into the air...gee I wonder why :p

So question for the pros, how does one de-solder a component that is designed to wick away heat?
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Old 09-23-2013, 04:28 PM   #11
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Default Re: Vizio E421VA No Sound Through Speakers

Lol darn heatsink. Do you know how many watts your solder iron is? I wonder if a high ish wattage one would provide more of the heat quickly enough to melt the solder before the heat gets transferred -- this is coming from someone who barely has any soldering experience though =/
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Old 09-23-2013, 05:19 PM   #12
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Default Re: Vizio E421VA No Sound Through Speakers

It's a Weller WLC-100 40 watt solder station, which from what I'm reading on here is pretty good brand, but very weak model.
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Old 09-23-2013, 05:38 PM   #13
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Default Re: Vizio E421VA No Sound Through Speakers

You'd really be wanting an 80 to 150W soldering iron to take out a heatsink. It helps to have two: one high power one for heavy lifting, like that heatsink (it doesn't need to be temperature regulated, so it can be a relatively inexpensive unit), and the Weller for more delicate work.
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Old 09-26-2013, 07:08 AM   #14
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Default Re: Vizio E421VA No Sound Through Speakers

You might also consider a Chipquik kit to help you remove both the sink and the chip beneath. It has a special low temperature solder that you mix with the existing solder to lower the temperature necessary to remove it. Very useful for sinks and surface mount chip removal.
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Old 09-29-2013, 08:09 PM   #15
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Default Re: Vizio E421VA No Sound Through Speakers

http://www.youtube.com/watch?v=BQOrO...eature=mh_lolz

This is my attempt and fail to remove the heatsink with a 100w iron. I think I need some solder to flow to transfer the heat properly, I couldn't get the solder to melt even a bit.
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Old 09-30-2013, 08:47 AM   #16
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Default Re: Vizio E421VA No Sound Through Speakers

If you just heat the lead, you won't get far. You need to heat the joint itself (it will help to add a little lead-tin solder to the joint to lower the melting point) Heat the joint< use the solder sucker to get all of the solder out. It may take a few tries. Then use a needle nose plier to break the pin away from the joint. Then it should come out. The heatsink will have Thermal compound on it so it may be stuck. Just wiggle and pry till it comes loose.
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Old 09-30-2013, 05:55 PM   #17
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Default Re: Vizio E421VA No Sound Through Speakers

I just got a chance to remove the board from the TV to look at the underside of that sound IC area (see picture). It doesn't seem (at least to my virgin eyes) that there is any burntness/bulging to it like you had on yours. I'm not exactly sure why there is that rectangular blanket of solder overlaying part of those PCB lines. From pictures of the same board online, they have that similar blanket of solder but look slightly different.

Have you tried using that desoldering suction at the same time as you're holding the iron tip on the joint, as the solder is melting? You've probably done it all sorts of ways, but from the video it looks (maybe) like there's a sizeable gap in time between when you pull the iron tip away and when you begin to suction?
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Old 10-10-2013, 10:29 PM   #18
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Default Re: Vizio E421VA No Sound Through Speakers

After a lot of scraping and gradual chipping away at the solder, I was finally able to get the heatsink off. I wasn't successful with the soldering iron either, so I ended up using a pair of nail clippers to slowly and carefully chip and wear away the solder. Eventually there was only a thin amount of solder left to where I was able to wiggle the heatsink with pliers and pull it off the board...took a lot of persistence.

There's nothing visibly abnormal with the sound IC as far as I can tell. I put the board back into the TV and turned it on. While on, I touched the sound IC to see if it gets warm/hot...which it does, but I'm guessing that's probably normal since it uses a heatsink. I also pressed on it to exert a little pressure, hoping that might connect any dry/broken solder joints while I'm pressing, but to no avail.

The model number of the sound IC is STA339BW (see attached photos). I don't know if there's any way to test the IC without simply replacing it.
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File Type: jpg photo 1.JPG (772.1 KB, 69 views)
File Type: jpg photo 2.JPG (512.7 KB, 66 views)
File Type: jpg photo 3.JPG (805.9 KB, 67 views)
File Type: jpg photo 4.JPG (710.9 KB, 53 views)
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Old 10-14-2013, 09:17 PM   #19
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Default Re: Vizio E421VA No Sound Through Speakers

I don't have much experience with soldering SMDs and am looking into possibly using soldering paste. I'm considering lower temp pastes so that I won't fry the sound IC SMD with my inexperience but am a little worried about the temperature tolerance of the paste in the long run when the device is running and gets hot.

Would the Chip Quik Low Melting paste ("Melting Point 138C 281F (Eutectic)
87% Metal Particle Size 25-45 Microns") be an acceptable choice for this application?

The datasheet on the STA339BW sound IC states an "operating junction temp" of -20 C to 150 C, and a "storage temp" of -40 C to 150 C. Here are some additional numbers:

Tth-sdj Thermal shut-down junction temperature: 150 C
Tth-w Thermal warning temperature: 130 C
Tth-sdh Thermal shut-down hysteresis: 20 C

Any thoughts or recommendations on this are appreciated.
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