VIZIO E470VA Dead

[bwilliams60]

I have this 47" Vizio that shows no signs of life. No indicator light, no video, audio, nothing.
Checked power supply, no voltage out of any of the connector pins and no voltage for PS ON. Checked on the cold side of the transformers - no voltage.
Went to hot side, checked voltages at rectifier - found 60V, 120V, 0V, 60 V respectively from left to right.
I will post pics later for this unit but just wondering if anyone might have a schematic for this power supply. I know it is dead, just need to know where it died.

[bwilliams60]

Re: VIZIO E470VA Dead

Update to my dead Vizio. I am uploading pictures of the set. There seems to be no voltage from the power supply to anything. All voltages including PS ON is 0VDC. I would like to troubleshoot the power supply if that is where I should be. There is no screen, not even VIZIO logo lighting. Dead.

[budm]

Re: VIZIO E470VA Dead

When you make measurement in the Primary side you do not use chassis/safety Gnd as a ref. for your meter, the Negative leg of the main filter cap is the GND ref. for the Primary circuit. For Primary AC measurement, you will measure between Line and Neutral.
So what DCV do you have when you measure between the two legs of the main filter caps.

[Ltank]

Re: VIZIO E470VA Dead

If you have no yellow Vizio logo lighted then you have no 5vdc. Trouble shoot that sircuit 1st, then see if set will turn on from there.

[bwilliams60]

Re: VIZIO E470VA Dead

Okay I checked the DC voltage across the 68uF 450V caps and it measured at 165 VDC. I also have a new observation. When I first plug the unit in, the VIZIO logo lights for a moment and then goes out. Also 5V found on PS ON for that same duration.
budm, thank you for the ground tip. I was measuring from the chassis for all my measurements. So when I am checking primary side, best spot is on -ve leg of filter caps?
Where to from here?

[budm]

Re: VIZIO E470VA Dead

Okay I checked the DC voltage across the 68uF 450V caps and it measured at 165 VDC. I also have a new observation. When I first plug the unit in, the VIZIO logo lights for a moment and then goes out. Also 5V found on PS ON for that same duration.
budm, thank you for the ground tip. I was measuring from the chassis for all my measurements. So when I am checking primary side, best spot is on -ve leg of filter caps?
Where to from here?

So the standby 5.2V is no longer there?
So none of the pins have any DCV at all for sure?
http://assets.shopjimmy.com/media/ca...cgc10026ar.jpg
It seems to me that the standby 5V was there and then disappear otherwise you will not see the VIZIO logo comes on at all.
It may be EEPROM problem.
http://www.shopjimmy.com/catalogsear...q=VIZIO+E470VA

[bwilliams60]

Re: VIZIO E470VA Dead

Hi budm. As I said in post #5, the 5V can be seen on PS ON but only for the exact same amount of time as the VISIO logo lighting up. After that, it is gone. No other power that I can see.

Can this be repaired at the component level? What else can I check?

[budm]

Re: VIZIO E470VA Dead

Hi budm. As I said in post #5, the 5V can be seen on PS ON but only for the exact same amount of time as the VISIO logo lighting up. After that, it is gone. No other power that I can see.

Can this be repaired at the component level? What else can I check?

I am not looking for PS-ON signal, I am looking for the standby 5.2V to see if it is present and stable or not, no steady standby 5.2V then nothing will work.
So per your statement "No other power that I can see" so the 5.2V appears and then disappear at the 5.2V pins?

[bwilliams60]

Re: VIZIO E470VA Dead

I am sorry budm, I am fairly new to this so I hope you have some patience. I measured the 5.2V terminals, which are the top two in the connector as I turned the set on. It came right up to 5.09 v right away and then dissipated down to 1V when the logo shut off. After that it slowly drained down to nothing. I tried it again with the control board disconnected and it did the same thing, but took longer to do so. I will recheck my other voltages as I power it up and see what comes up.

EDIT: Here is what I found on each terminal as I powered the set up.
5.2 -> 5.1 and then dissipates down near zero
5.2 -> 5.1 and then dissipates down near zero
PS ON -> 4.92 and then dissipates
24 -> 24.87 and then dissipates
24 -> 24.87 and then dissipates
12 -> 11.82 and then dissipates
12 -> 11.82 and then dissipates
DIM -> 3.4 and then dissipates
ON_OFF -> 0.5 and then dissipates

Hope this helps

[budm]

Re: VIZIO E470VA Dead

"It came right up to 5.09 v right away and then dissipated down to 1V " OK, that is not normal, the STANDBY 5.2V is an always on power supply that is running 24/7 hwne you have the TV plugged into the outlet. So it is either there is problem in the standby pwoer supply or the main board is load the standby power supply.
You can try this quick test, unplug the TV from the outlet, then heat that section I marked with hair dryer for 2~3 minutes, then plug the TV in and monitor the 5.2VDC pin, then turn the TV and see if the 5.2V will stay on at 5.2VDC. When STBY power supply drops out, every thing will drop out with it.
Picture provided by shopjimmy.

[bwilliams60]

Re: VIZIO E470VA Dead

Budm, you are a genius. I'm not sure what we just did, but it works! I heated that section of the board up for three minutes to about 130 degrees, plugged it in and 5.02VDC right on the nose. Pushed the On button and the screen sprang to life and No Signal started dancing around the screen. Very cool.
Okay, so what did we just do, and how do I fix it from here? Was that the 5.2V power supply section?
One other question. What are the components that look like diodes and are marked FB10x? I can't see any markings on any of them.

[retiredcaps]

Re: VIZIO E470VA Dead

The circled area by budm has a startup capacitor that is feeding the SMPS IC (7 pin IC). That capacitor likely has high ESR. By warming it up, the capacitor's ESR is lowered allowing the circuit to work.

Replace the capacitor with a Panasonic FC or FM capacitor from a reputable distributor like mouser or digikey.

FB = ferrite bead.

[bwilliams60]

Re: VIZIO E470VA Dead

Thank you retired caps. After I went back and looked at the board, I figured it had to be the cap or the VIPER27 controller he was after. How does one figure out such a thing? Experience?
I will replace the cap tomorrow and see if it fixes the problem. I will post back when it is done.

[retiredcaps]

Re: VIZIO E470VA Dead

How does one figure out such a thing? Experience?

Well, budm has close to 20,000 posts, he volunteers every Saturday at some electronics recycling depot and over 20+ years of electronics so he knows what to troubleshoot first.

When you don't have standby voltage, it quickly narrows down the list of culprits. I personally would have measured the voltage across the startup cap. If it didn't measure around 14V, I would have replaced the cap with a Panasonic FC.

My guess is this cap is 22uF 50V. Most startup capacitors are either 10uF, 22uF or 47uF.

Since almost every consumer electronic device has a SMPS, it pays to know how they work and troubleshoot one.

[retiredcaps]

Re: VIZIO E470VA Dead

PS. You can learn a lot by participating in remote troubleshooting or following a regular member's posts. You have to rely on observation, communication, deduction and other skills to be really good.

When I started, I read, everything that PlainBill wrote and learned a lot.

[bwilliams60]

Re: VIZIO E470VA Dead

I have been reading a lot on SMPS and just got Justine Yangs book on SMPS. Not sure how good it is but it's a start. I'm sure like everyone else, it is a lot of time and experience. The cap is a 10uF 50V capacitor. I only have Phillips (old stock) and jamicon caps here right now or I would fix it right away. I will pick up some Panasonic caps tomorrow from my local supplier.

[retiredcaps]

Re: VIZIO E470VA Dead

So when I am checking primary side, best spot is on -ve leg of filter caps?

Yes. I also recommend you using clips so you probe hands free on the hot side. Or at minimum one clip on the negative leg of the large capacitor so that you can keep one hand behind your back.

An "oops" moment on the hot side will often lead to bad consequences.

[retiredcaps]

Re: VIZIO E470VA Dead

I only have Phillips (old stock) and jamicon caps here right now or I would fix it right away.

As a test, you can whack in any of the above and it should work temporarily.

[bwilliams60]

Re: VIZIO E470VA Dead

I have been doing automotive DC electrical since I was a kid and did electronics when I was young as well. My brother who was an electrician taught me well on the dangers of Ac voltage and how to handle it so I take the utmost care when measuring and usually try to do it hands free where possible. Hydro guys taught me to keep left hand in pocket and so it goes. Have a few years left and plan on living them so thanks for the heads up. I use CAT III probes and insulated clips like the ones above. I also have bckprobes I use for cold side.

[retiredcaps]

Re: VIZIO E470VA Dead

BTW, the value of the startup cap, for test purposes, doesn't have to be exactly 10uF. It can be 22uF or even 47uF. You can even go down in voltage to 25V since the datasheet for the viper27 calls for a typical 14V start voltage (max 15V). A 16V cap, however, might be too low.

When I'm troubleshooting, I usually whack in what is close enough to see if that is the culprit and then, if it is working, I get the correct replacement.