Vizio E321vl power supply question

[bigtuna]

Hi,
We were visiting Grandma last weekend and found the Vizio E321vl TV was having trouble. Thought someone could answer a question about the power supply, maybe help in determining which board needs to be replaced.

Found the TV with no power, logo is out, and not turning on with power button or remote. I did the reset with holding down the power button, waiting and plugging back in. When it is plugged back in the logo is amber for less than one second and goes out dark again. No power.

Power supply board has no voltages present at the connector while the main board cable is plugged in. When I disconnect the main board cable from the power supply board, the 5.2V is present and steady on the first 3 pins of the header. No AC ripple.

I reconnected the main board cable, plugged the TV back in while watching the 5.2V lines. The 5.2V tries to come up for a split second and dies. The 12V or the PS ON control voltage is never comes on, always 0V. The amber logo tries to come on, but blinks off when the 5.2V dies.

Could the main board be loading down the 5.2V standby voltage or does this look like a power supply problem? Once narrowed down to the board level, I'll swap out whichever is the most likely culprit.

Appreciate any help...Dave

[Ltank]

Re: Vizio E321vl power supply question

With the main board disconnected you have the standby 5.2 vdc? The main board sends that voltage back to the power supply on. This tells the power supply to turn on. Disconnect the wires to the back lighting and check P.S. voltages. If results are the same then try the following. With the main board disconnected jumper with a 1k ohm resistor, the 5.2 vdc to the P.S.-On. This should turn on the P.S. if there are no shorts on output of P.S. and the jumper turns it on then the P.S. is fine. Then the problem would be the main board

[budm]

Re: Vizio E321vl power supply question

You are double posting, see
https://www.badcaps.net/forum/showth...930#post369930

[bigtuna]

Re: Vizio E321vl power supply question

You are double posting, see
https://www.badcaps.net/forum/showth...930#post369930

Sorry about that, not sure how the extra post got there. I delete the extra if I can.

[bigtuna]

Re: Vizio E321vl power supply question

Ltank, yes, 5.2Vdc is there when I plug in the board with the main board cable disconnected. I'll check the supply with the 1K res.

How much of a load should the 5.2V standby supply be able to take before collapsing?

budm, I'll check the cap value and post a pic of the board tomorrow.

Didn't see any way to delete the other post. May a mod can delete it for me.

Thanks guys.

[Ltank]

Re: Vizio E321vl power supply question

1k work well as does a 500 ohm some people use 100 ohms. I would not use a jumper without a resistor. Service manuals usually show how to do this if you have any doubts. Generally you can do this with the P.S. unloaded or loaded. I prefer loaded. If the P.S Can not drive the load current it will fail. If you test it unloaded then you see that ps works, then connect the load to se if it works. If not check the resistance of the load with a meter.

[budm]

Re: Vizio E321vl power supply question

The 5V power supply can easily handle 1A (about 5 Watts of power) of current, so you can use 5 Ohms 10 Watts as the load.

[bigtuna]

Re: Vizio E321vl power supply question

The 5V power supply can easily handle 1A (about 5 Watts of power) of current, so you can use 5 Ohms 10 Watts as the load.

If the 5V supply is ok then wouldn't pulling it down to 0v have popped a fuse or does it sense a short and cut out? I'll bring home a few resistors from work and test it tonight.

Thanks.

[bigtuna]

Re: Vizio E321vl power supply question

1k work well as does a 500 ohm some people use 100 ohms. I would not use a jumper without a resistor. Service manuals usually show how to do this if you have any doubts. Generally you can do this with the P.S. unloaded or loaded. I prefer loaded. If the P.S Can not drive the load current it will fail. If you test it unloaded then you see that ps works, then connect the load to se if it works. If not check the resistance of the load with a meter.

I'll check the load resistance from the main board when I pop the set back open tonight.

Thanks.

[bigtuna]

Re: Vizio E321vl power supply question

Thanks guys. The 5V supply wasn't staying up under load. Picked up a supply board for $26 and the set works fine. Appreciate the help.

[budm]

Re: Vizio E321vl power supply question

Good news, the old one may just have a bad start up cap.