Vizio E550i-A0 no power, no standby light

[x_orange90_x]

I have a Vizio E550i-A0 that will not power on. It also does not display the standby light in the corner. I disconnected the main board cable to see if the backlights would light but they did not (maybe this is normal for this set?). I checked the voltages on the plug and they all read in mV or 0, so there's no voltage there. The fuses are ok, and the voltages of the 450v caps read about 160v. I see no visual damage on either the power supply or main board. I have read online that the main board is usually the culprit in this model, but not getting backlights with the main disconnected makes me second guess.

If there's power on the hot side but not the cold side, does that mean something is wrong with the power supply? Or is the main board supposed to turn on the cold side?

[R_J]

Re: Vizio E550i-A0 no power, no standby light

Which power supply is in it? post pictures so we can see what we are dealing with.

The first voltage you need is the standby voltage, if it is missing nothing works.

[x_orange90_x]

Re: Vizio E550i-A0 no power, no standby light

Which power supply is in it? post pictures so we can see what we are dealing with.

The first voltage you need is the standby voltage, if it is missing nothing works.

Pictures are attached. Thanks for the reply! I can post pics of the bottom later if needed.

[R_J]

Re: Vizio E550i-A0 no power, no standby light

Check FP802S fuse, if it is good, Check if you have A5V on J807 jumper or pin 1,2 of cn102

[x_orange90_x]

Re: Vizio E550i-A0 no power, no standby light

FP802S has continuity, and there is no voltage on Pin 1,2 of CN102. I can check that jumper later when I get home.

[R_J]

Re: Vizio E550i-A0 no power, no standby light

FP802S has continuity, and there is no voltage on Pin 1,2 of CN102. I can check that jumper later when I get home.

The jumper is the same point as pins 1,2 of cn102. You don't have the standby voltage so the standby circuit is not working. Check if RS816 resistor is good and not open, if it is ok (0.6Ω) If it is ok, check the voltage across CS804 and CS805, or using J874/J875 as (hot) ground, check the voltage on DS802 and DS814 cathode, If there is voltage but under 10vdc I would replace CS804 and CS805 and CM806 as well

[x_orange90_x]

Re: Vizio E550i-A0 no power, no standby light

I will check those. BTW, when I checked voltage on the CN102, I used the upper right grounded screw as my groud. Should I recheck with my ground probe somewhere else?

[EazyBone]

Re: Vizio E550i-A0 no power, no standby light

You can use the grounded screw yes for cn102. Just stick the black probe into a wall mount hole and leave it there to test.

[R_J]

Re: Vizio E550i-A0 no power, no standby light

That ground screw should be ok for checking voltages on the cold side of the power supply but for voltages on the primary side you can not use that ground, you must use what is referred to as hot ground IE BD801S (-) or CP814s (-)

[x_orange90_x]

Re: Vizio E550i-A0 no power, no standby light

CS804 is reading about 5v. CS805 varies a bit. It went to 5v then dropped to .005v, second time I got 3v then drop to .005 and CM806 is at 8v.

I accidently discovered that removing the positive lead of my meter from the cap gives me the above voltages with just the negative connected. Also the voltages will stay at 5, 5, and 8v respectively.

[R_J]

Re: Vizio E550i-A0 no power, no standby light

What is the number on the sot23-8 ICS801 ic. I suspect it is trying to start but the caps are bad and not charging

[x_orange90_x]

Re: Vizio E550i-A0 no power, no standby light

What is the number on the sot23-8 ICS801 ic. I suspect it is trying to start but the caps are bad and not charging

Where are you seeing that on the board?

NVM I see it's on the bottom.

[x_orange90_x]

Re: Vizio E550i-A0 no power, no standby light

I can't really make our exactly what it says. Check the attached pic and see what you can read. I can definitely see the numbers but can't differentiate between S 3 and 8.

It looks like it might say S3320 and 304

[R_J]

Re: Vizio E550i-A0 no power, no standby light

Looks like a S3320, same as SEM3320, I don't see a datasheet but I suspect the ic is ok,

CS804 is the vcc capacitor, the ic will provide a small current to charge the cap, then DS802 supplies the run voltage, so check that diode, and check RS815 [000] 0Ω resistor. The normal run voltage across CS804 is likely around 15~20vdc

You may also want to check that RS807, RS806 and RS805 (243, 24KΩ) are good, sometimes one of them can go open, also RS802, RS803, RS804 (475, 4.7megΩ)

And check that the standby output diode DS853 is not shorted, It is likely ok but worth checking that it is not killing the standby voltage

[x_orange90_x]

Re: Vizio E550i-A0 no power, no standby light

Looks like a S3320, same as SEM3320, I don't see a datasheet but I suspect the ic is ok,

CS804 is the vcc capacitor, the ic will provide a small current to charge the cap, then DS802 supplies the run voltage, so check that diode, and check RS815 [000] 0Ω resistor. The normal run voltage across CS804 is likely around 15~20vdc

You may also want to check that RS807, RS806 and RS805 (243, 24KΩ) are good, sometimes one of them can go open, also RS802, RS803, RS804 (475, 4.7megΩ)

And check that the standby output diode DS853 is not shorted, It is likely ok but worth checking that it is not killing the standby voltage

I will check those tonight. May I see the schematic you're working from so I can understand the flow?

[R_J]

Re: Vizio E550i-A0 no power, no standby light

I'm using the board pictures from shopjimmy and my knowledge of these circuits, I'll see if I can find a schematic that uses this ic.

[lotas]

Re: Vizio E550i-A0 no power, no standby light

Sem3320

[R_J]

Re: Vizio E550i-A0 no power, no standby light

Thanks lotas, I just found it as well after searching for the ic.
x_orange90_x , this schematic is for the standby circuit and is very close except for the component id's IE C803 = CS804; D802 = DS802

Also this schematic does not have a pfc circuit like your board does, yours will have an additional supply (DS814) off the standby circuit to feed the pfc circuit vcc.

[x_orange90_x]

I'm not sure what's going on with the forum but the UI is completely changed now and I want able to login at all yesterday. My last two posts on this thread are not showing up either.

Anyway, I disconnected one of the legs of that diode and it reads good.

[x_orange90_x]

I'm still not sure if I'm seeing the website correctly. Still no replies here.

If you can see this, please send me a direct message so I'll know.