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Old 01-16-2018, 02:10 PM   #1
nosugartonight
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Default vizio dead set

Kinda new to this so bare with me. This is a vizio E420V0. Completely dead,no power light,nothing. On the main board,"3642-0972-0150(41)" the 3v nano fuse is blown. From the fuse through a cap goes to u6 a IC or eeprom.not sure what it is. If I'm doing this correct with meter in diode mode. From pin one to last pin"straight across" It shows shorted. Thinking this is what I need to replace. I can't find it. The part number is LA8004PG AN08. I'm I on the right track.
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Old 01-16-2018, 02:26 PM   #2
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Default Re: vizio dead set

https://www.badcaps.net/forum/attach...1&d=1516135770
Are you saying that the white fuse by the connector of the main board that goes to the power supply is blown?
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Old 01-16-2018, 03:05 PM   #3
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Default Re: vizio dead set

No it the little gray nano fuse.right below the cable from the power supply. They are two fuse's one is 5v other is 3v.
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Old 01-16-2018, 03:10 PM   #4
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Default Re: vizio dead set

I believe that ic is similar to a ap3435, pin 1 (Vcc) can be connected to pin 8 (Vin), It is a step down converter from 2.7v to 5.5v input to 1.2 volts output on pin 7, check if pin 1,8 or7 are shorted to ground (pin3 & 6)

Last edited by R_J; 01-16-2018 at 03:14 PM..
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Old 01-16-2018, 03:14 PM   #5
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Default Re: vizio dead set

Main board:
http://assets.shopjimmy.com/media/ca...0150-top_5.jpg

Power supply board:
http://assets.shopjimmy.com/media/ca...1030-top_4.jpg

The two fuses on the main board:
F1 is for the 5V STBY, that 5VSTBY is fed to many circuits on the main board so shorts circuits can be any where that the 5VSTBY is connected to.
F2 is for switched 12V.

Last edited by budm; 01-16-2018 at 03:20 PM..
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Old 01-16-2018, 03:52 PM   #6
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Default Re: vizio dead set

Pins3,6 and 7 show ground
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Old 01-16-2018, 04:06 PM   #7
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Default Re: vizio dead set

All voltages are good on power board. Is u6 an IC ? No voltage on any pin just as I suspect because fuse blown.
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Old 01-16-2018, 05:05 PM   #8
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Default Re: vizio dead set

Ok I didn't have a 3v nano fuse so I used a jumper wire. I now have back light but it is flickering really fast. Anyone have any ideas. Also will not shut off with power button.
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Old 01-16-2018, 05:46 PM   #9
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Default Re: vizio dead set

Yes u6 is an ic, it is a stepdown converter (post#4) What voltages do you have on its pins? Does it get hot to the touch?
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Old 01-16-2018, 06:11 PM   #10
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Default Re: vizio dead set

Does not get hot or warm.pin 1-5.07 pin2- is all over the place,but slowly goes to 0 pin 3 and 4 - .796 pin 5- 1.6 pin 6- .9 pin 7- 1.850 pin 8-5.14
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Old 01-16-2018, 06:43 PM   #11
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Default Re: vizio dead set

Because I am going by a different ic part number "ap3435" I can't be certain about what the exact output voltage on pin 7 should be, but it seems to be fine.
Pin 2 has no connection
pin 3 and 6 should be ground
See page 15 of the pdf
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Old 01-16-2018, 08:46 PM   #12
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Default Re: vizio dead set

Yes I agree,it seems fine now that I seen the data sheet. Thanks for the link. Are you familiar with u18. That is a eeprom right. I looked at the voltages and two of the pins have high fluctuations reading. Where can I find data sheets
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Old 01-16-2018, 08:49 PM   #13
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Default Re: vizio dead set

So right now the 5VSTBY Voltage is going up and down? and the resistance between GND and the jumper is?
You were using diode mode for checking for shorts:
Post# 1: 'If I'm doing this correct with meter in diode mode. From pin one to last pin"straight across" It shows shorted.' You should use Ohm mode instead.

Last edited by budm; 01-16-2018 at 09:02 PM..
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Old 01-16-2018, 09:26 PM   #14
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Default Re: vizio dead set

5vstby is steady. As of now,when the set is plugged in. Black light starts flickering fast. Only way to shut the set off is to unplug. Voltages I was talking about going up and down is on u18, wich I believe is a eeprom.
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Old 01-16-2018, 09:47 PM   #15
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Default Re: vizio dead set

How about the shorts that you indicated in POST #1? What is the resistance reading?
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Old 01-16-2018, 10:17 PM   #16
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Default Re: vizio dead set

I guess I was doing it wrong. I was in diode mode. No sure how to check resistance in ohms. Ground to pin or pin one to each other pin . I would assume ground to pin.
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Old 01-17-2018, 02:52 PM   #17
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Default Re: vizio dead set

Does anyone have any ideas on what would cause the back lights to flicker.I'm thinking it's in the main board because they start flickering as soon as the tv is plugged in ��
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Old 01-17-2018, 03:08 PM   #18
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Default Re: vizio dead set

You can test the power supply/inverter board by itself by disconnecting the cable between power supply board and the main board then use 1K resistor between 5V STBY and the PS-ON pin, another 1K resistor between 5VSTBY and the BL-ON (I ON-OFF) to force on the power supply and the backlights when AC is applied to the board, the backlights should come on and stay on as as as the AC is present. If the backlights still do not come on then you will need another 1K resistor between 5V stby and the DIM pin.

Last edited by budm; 01-17-2018 at 03:11 PM..
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Old 01-17-2018, 05:28 PM   #19
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Default Re: vizio dead set

I don't have any resistors.I'll have to pick some up tomorrow and let you know how it goes. Thanks for the info.
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Old 01-18-2018, 05:36 PM   #20
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Default Re: vizio dead set

Was unable to find resistors.was thinking about robbing from old board.do you know the color code for 1k
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