Small silver caps on Vizio E470VL main board

[Taterbug]

I received a replacement main board in the mail for the Vizio tv I have been working on. This board seems to be bad. I have no 12 volts and Backlight still not working. This board was replacing one I had intermittent problems with. I noticed that one of the small silver caps was missing. You could actually see the tab imprints in the solder. I tried to remove the cap off of the old board and replace it but no luck. Are these small silver caps that Vizio uses precision electrolytic caps and if so where can I get some of them. I have ordered a new regulator (U3) that is getting extremely hot to touch as soon as you turn on the tv. I was wanting to replace some of these caps also. Most of them seem to be 100 MFD 16volt. VIZIO E470VL MAIN BOARD 0171-2272-3253 3647-0292-0150 I am attaching a photo of the regulator that is overheating and the surrounding caps around it are the ones I want to replace. The voltages on the regulator read good. 4.8 volts, 2.2 volts and 3.2 volts on the tab.

[mockingbird]

Re: Small silver caps on Vizio E470VL main board

Hello,

Can you post their diameter? As well, the diameter for the cap that is not on the board.

[Taterbug]

Re: Small silver caps on Vizio E470VL main board

6.3 mm and 10mm both 100 mfd. the one that was missing was 6.3 mm and 100 mfd.

[mockingbird]

Re: Small silver caps on Vizio E470VL main board

The caps shown in the picture are Nichicon UA and CD series (Note: These are ordinary electrolytic SMD caps, eventhough they have no top vent, and they are not polymer caps), here are their values:

(The "UA" series caps with the "C" suffix are 16V 100uF. The 6.3mm with the "V" suffix is 35V 100uF. The 8mm cap marked 220E is 25V 220uF, according to the CD Datasheet)

Here are some direct replacements:
35V 100uF 6.3mm x 7.7mm Nichicon "CD": 3438934
16V 100uF 6.3mm x 7.7mm Nichicon "UA": 3438961
25V 220uF 8mm x 10mm Nichicon "CD": 3438894


...but I'm curious why you state that:

the one that was missing was 6.3 mm and 100 mfd

...when the position the missing cap is perceivably supposed to be in looks like it is meant for an 8mm cap?

[Taterbug]

Re: Small silver caps on Vizio E470VL main board

Sorry but I should have added a photo of the area of the missing cap. This photo was of the silver caps around the regulator that is over heating. Thank you for your info. I will get some replacement caps on order.

[Taterbug]

Re: Small silver caps on Vizio E470VL main board

Also do you know what U3 feeds? It is overheating as soon as I turn tv on but voltages look normal on the output?

[mockingbird]

Re: Small silver caps on Vizio E470VL main board

Sorry, couldn't tell ya... If you had the schematic of the board, you could check up which version of the TO-263 G1084 that is (Fixed or variable), and then replace it with a better rated part. Spec sheet lists it at up to 85c.

[budm]

Re: Small silver caps on Vizio E470VL main board

"I have ordered a new regulator (U3) that is getting extremely hot to touch as soon as you turn on the tv" that means too much current is flowing through it, there should be two caps connected in parallel, one is the electrolytics (like the one that is missing) and the small SMD MLLC type which when it goes bad, it will shorted out. The regulator can also gets hot if it is oscillating at high frequency, you will need the scope to look at the input and output of the regulator. It does not sound good when the replacement board already has missing part, it can have more problem with more than just missing part.

[Taterbug]

Re: Small silver caps on Vizio E470VL main board

These boards are hard to find at an affordable price. I am going to replace the regulator and associated caps and hope for the best.

[ecking767]

Re: Small silver caps on Vizio E470VL main board

before buying parts, I will trace the output of the regulator, U3 look like its feed U4 input. its will take about 30 minutes or less to trace those regulators to find out who it is supplying voltage too.

[Taterbug]

Re: Small silver caps on Vizio E470VL main board

Thanks

[horn34]

Re: Small silver caps on Vizio E470VL main board

Thanks

Did you ever get yours fixed?

[mariushm]

Re: Small silver caps on Vizio E470VL main board

U3 is a *1084 linear regulator (from memory 1084 is maximum 5A output).
Yours is an adjustable version of the 1084 linear regulator ... may not be the same manufacturer but you can follow the LM1084 datasheet for reference :

The capacitor missing is on the output of the regulator.
The tab and the center pins are output voltage.
The left most pin is Ground/ Adjust as you can see by the printing by the pin and the adjust resistors connected to it.
The rightmost pin is input voltage, the decoupling capacitor C5 and the print Vi should be obvious sign.

You can figure out what output voltage that regulator should have by measuring the input voltage and by measuring the resistors connected to the ground pin.
The output voltage is configured by the formula Vout = 1.25 ( 1 + R2/R1) where R1 and R2 are the two resistors (R2 is the resistor with one end connected to ground, in your picture R38

So for example, if this regulator has 5v on the input, considering it has a dropout voltage of around 1v, it must output at most 4v. So the two resistors should have such values that the output should be some lower voltage like 3.6v , 3.3v , 2.5v etc.
Once you know the output voltage, you know you must pick capacitors with voltage rating above that voltage.

The output capacitor isn't very critical but the capacitor must be big enough to handle up to 5A of current, if the regulator is used for such high currents. So even though you may figure out the regulator outputs 3.3v in which case a 6.3v rated electrolytic would be enough, it may still be smart to use a larger capacitor with a voltage rating of 10v or even 16v.

Since it's a linear regulator, the ESR isn't critical, in fact ultra low esr capacitors may actually be bad - in particular in the case of 1117 linear regulators which I see are present on the board you must use capacitors with ESR values above 0.1 ohm.

As far as I know, *1084 linear regulators aren't that picky about ESR but still it would be a good idea to keep the esr just average.

The LM1084 datasheet says capacitor with a value of 150 uF on the output is "enough" to keep the adjustable version of the regulator but there's nothing about using higher capacitance .. as long as the esr doesn't go very low.

All the other regulators seem to have a 100uF 16v capacitor on the output ... for 1117 is a good value but for 1084 i'm not quite sure. I would use a slightly bigger value than that, maybe 220uF or even 470uF ... those should be a good choice for you... my guess is they just tried to save money by reusing same components wherever the exact value wasn't critical.

And since ESR isn't critical, any capacitor would work. No need to go with a surface mounted capacitor unless you really care about looks.
You can use leaded capacitors, just bend the leads slightly, tin them with some solder and then solder the leads to the pads and you're done.
I wouldn't use very low esr capacitors like Panasonic FM or FR .

From surface mount, I'd consider Panasonic FK or Nichicon UD , Nichicon CD
leaded capacitors ... panasonic fc , rubycon yxf , nichicon ps , pj, he etc