Vizio E470i no power

[AcGeorgiegirl]

Re: Vizio E470i no power

Are the LCD strings generic, or are they proprietary to the model of the tv? I have 3 other Vizio and 2 Samsung tv's that may/may not be repairable(I'm in the process of taking a look at each). It's a shame how often, though, even the same brand and series aren't compatible in swapping stuff out. Panels, I understand, are pretty much never swappable except exact models, right?

[AcGeorgiegirl]

Re: Vizio E470i no power

Yes, that's my board.

[AcGeorgiegirl]

Re: Vizio E470i no power

Main is irrelevant to this now.

You have the voltages all coming up yet still no backlight.

Ok, just to clarify for me....the voltages for everything but the 2 standby's aren't there unless I jumper them...so doesn't this mean there's something up with here, as well?...they aren't getting powered through the correct paths(ie)?

[newtothis]

Re: Vizio E470i no power

Well there still could be an issue with the mainboard but you should of gotten backlights on from the tests we did indicating an issue.

Plug your main back into the PSU and try switching it on... Observe the BL_ON and PS_ON voltages to see if they rise or not

[AcGeorgiegirl]

Re: Vizio E470i no power

That makes sense.
Ok. The Ps-on and BL-on are at 3.21 and 3.17v with Main connected and after hitting "on" button. The power does come on, but you wouldn't know(no sounds, glow) and for around 5 seconds I can see the "V" logo on the screen, using a flashlight. I've never been able to see this before. I did replace the small-sized fuse on the board yesterday, because I found that it had no continuity. Maybe that's the difference in getting a picture. Also, the logo stayed as long as that proverbial little blue light was lit. It fades to nothing and so does screen. The v's are present as long as it seems the tv is on, even after the 5 seconds of logo showing using flashlight. I tested by hitting the "on" button, and then get 0 v's again.

[newtothis]

Re: Vizio E470i no power

It is confirming what we suspect atm.

Let budm trace the circuits and he will advice you further

Your main is OK btw

[AcGeorgiegirl]

Re: Vizio E470i no power

...to correct what I last wrote...the logo's fading isn't related to the little blue light fading, as I assumed. I pressed the menu button after the logo gone and blue light gone, and could see the menu on screen with a flashlight. I can now see whatever I put onto the screen with physical buttons(input choices, etc) with the flashlight as long as tv is turned on.

[AcGeorgiegirl]

Re: Vizio E470i no power

It is confirming what we suspect atm.

Let budm trace the circuits and he will advice you further

Your main is OK btw

You guys are my new best friends

[newtothis]

Re: Vizio E470i no power

Off topic but are you female? Just your username indicates it

[budm]

Re: Vizio E470i no power

So it has two LED driver circuits for two sets of the string, more likely one string for left edge and one string for the right edge of the LCD panel.
You need to monitor the Anode of the LED string 1 and string 2 to see what DCV you get when you first turn on the TV, I am looking for the Voltage to jump up high and then settle down to the lower Voltage, I also need to know for sure if you do see the backlights flash on for second or not.
BTW, what is the DC Voltage rating of those two filter caps I marked?
Pictures provided by SHOPJIMMY.

[AcGeorgiegirl]

Re: Vizio E470i no power

Off topic but are you female? Just your username indicates it

Yes.

[AcGeorgiegirl]

Re: Vizio E470i no power

You need to monitor the Anode of the LED string 1 and string 2 to see what DCV you get when you first turn on the TV

Ok, I see where you marked for measuring a LED string, but I'm not sure there's supposed to be two of these...one for each string?

[AcGeorgiegirl]

Re: Vizio E470i no power

I don't "get" strings, I think, is what's tripping me up. Are the 2 circles at the ends of the line you're pointing to the anodes for string 1 and 2?

[AcGeorgiegirl]

Re: Vizio E470i no power

...also, with testing the filter caps, I'm not certain my DMM will give nearly accurate reading unless I desolder/disconnect one lead. Is that true? Mine doesn't read capacitance or ESR...just ac/dc volts, diodes, amps, and ohms.

[budm]

Re: Vizio E470i no power

Ok, I see where you marked for measuring a LED string, but I'm not sure there's supposed to be two of these...one for each string?

I hope you know what the Diode symbol is to be able to tell what is Anode and what is Cathode, please look it up. You will put the meter in DCV, BLACK probe on the chassis, the RED probe on the Anode of the the LED string #1, turn on the TV and observe the readings, then turn off the TV, then do the same on the ANODE of the LED string #2. You see that I drew Diode symbol on the connector that goes to the LED strings of the panel.

[AcGeorgiegirl]

Re: Vizio E470i no power

I hope you know what the Diode symbol is

I attached a pic with marks I made to show you where I am looking. Yes, the anode side is the part that looks like an arrow. I just don't know where each string's anode is, on the board. I see where you drew the diode symbol for each string, and the only other symbols I see are the ones I circled in blue, which are two that look the same...do I touch the probe to the anodes of each of these? I also circled the area that originally I was focused on, the "Need Verification". I was thinking this was one of the string's area you wanted me to test, but didn't know how to locate the anode portion(!). I am looking for a soldered post that's an anode side of a "string", though not understanding, I think, what a string looks like. Maybe I'm thinking wrongly...that it is similar to a cap's connectors or a resistor's. Sorry I'm so confused!

[budm]

Re: Vizio E470i no power

Please see the attached picture.
BTW, you can take the measurement on the top side of the board right at the connector pins.

[newtothis]

Re: Vizio E470i no power

***EDIT***

budm got there while my image was uploading

[AcGeorgiegirl]

Re: Vizio E470i no power

Thanks, guys- You were telling me this, but I didn't get it! Quick question...should the psboard be connected to the other boards for this test, or just to the ac?

[newtothis]

Re: Vizio E470i no power

Plug all boards in when doing the test