Vizio E321VL

[killian6pk]

I got this TV as dead from a friend. There were no lights showing on Vizio label on the front of the TV. I checked the power board for power. The blue wire from the AC Input shows 59V. The brown wire shows 63V. The main fuse shows 63V with common on ground screw at AC connector. The large cap shows 0V with common to screw and red probe to positive side of cap. With both black and red probes on cap I get a reading of 10V.

On the main board there are two smd fuses. Both show 0.1ohm. On Inverter board there are two fuses. The first is small 0.75A / 63V. It reads 0.7ohms. The second is larger and is rated at 6.3A / 125V. It reads 0.1ohms.

I am at a loss as to why I am not getting the correct power to the fuse and the large cap. Is is possible or likely that the power cord is bad? Are the two readings taken from the AC connector on the power board what are expected?

I replaced all the Electrolytic Caps on the power board including the large one. I also found 3 diodes that read funny when I tested them. So I replaced those 3. I also found one Zener Diode and a 1/4W resistor that I thought were bad and replaced those. One of the diodes, the Zener and the Resistor were all together near the heat sink on the right side of the power board picture. The other two diodes that I replaced were large. One of them you can see in the picture on the top side of the board near the two tall E.Caps.

Any thoughts will be appreciated.

[retiredcaps]

Originally Posted by killian6pk

The large cap shows 0V with common to screw and red probe to positive side of cap. With both black and red probes on cap I get a reading of 10V.

1) Are you measuring AC or DC across the large filter cap? You should be measuring DC and be getting around 165 to 170V DC.

2) What is the resistance reading of the main fuse on the power board?

[selldoor]

I would be inclined to start again.
First check your meter - on Ohms - touch the probes together - should read
nil or very close. Next Meter on volts DC test a couple of batteries/cells.

Next with meter on Volts AC Care - High voltage test- Black probe on Blue cable Red probe on Brown Cable should be 120VAC.
Black probe on Blue cable red probe on fuse should still be 120VAC

If that is OK then Set Meter on 600vDC and put the black probe on the negative leg of the big cap and the red probe on the positive leg of the big cap
should be around 170VDC

[killian6pk]

Originally Posted by retiredcaps

1) Are you measuring AC or DC across the large filter cap? You should be measuring DC and be getting around 165 to 170V DC.

2) What is the resistance reading of the main fuse on the power board?

With DC Voltage set on AutoRanging DMM. I get 000.3V. On Large Filter Cap.
At AC connector on Power Board with AC set on DMM I now get 124.4V.
On the Main Fuse I get 0.1ohms and with AC setting checking Fuse with Black Probe on grounding screw and Red Probe on leg of Fuse I get 62.9V. Retiredcaps check post #5.

[killian6pk]

Originally Posted by selldoor

I would be inclined to start again.
First check your meter - on Ohms - touch the probes together - should read
nil or very close. Next Meter on volts DC test a couple of batteries/cells.

Next with meter on Volts AC Care - High voltage test- Black probe on Blue cable Red probe on Brown Cable should be 120VAC.
Black probe on Blue cable red probe on fuse should still be 120VAC

If that is OK then Set Meter on 600vDC and put the black probe on the negative leg of the big cap and the red probe on the positive leg of the big cap
should be around 170VDC

Probes together showed 0 ohms
Checked meter with batteries: Used (but almost new) AAA tested 1.405v; New AA tested 1.63V
Checked AC imput connecter got 124.3V AC
With Black Probe on Blue wire and Red Probe on Main Fuse got 124.1V AC.
Set Meter on DC checked Large Filter Cap with Black on Negative and Red on Positive side got 0.0 V.
So at least I now have power going thru the Fuse. What should I check now since power is not getting to the Large Filter Cap (New)?
Also at the same time I changed the caps I pulled the Bridge Rectifier since I had read on another post that it sometimes causes a problem. I checked it. It checked out ok so I soldered it back onto the board. Same with the 2 TO220 packaged Schottky Diodes on one of the Heat Sinks.

[tom66]

Check your solder joints for the caps. Did you touch up the soldering around the bridge? If not, do this. Seems like there's an open circuit somewhere.

[awyatt2]

look around the power cord where it plugs in some sets have a fuse on one leg of ac coming in. if it goes you wont get full voltage. i have two sets here with fuses in the connector. a small plastic insert with a fuse underneath, look closely there is a fuse pic etched onto the plastic.all vizios don't have them but some do.i found the first one accidently by removing the plug assy, voltage was right at cord fell at the inside connector.when i had it in my hand i saw the fuse.

[killian6pk]

Thanks guys will check both of those suggestions and get back to you with results.

[selldoor]

I should have said check ac voltage on BOTH end of the fuse to the blue cable

Can you post a pic of the bottom of the board?

[killian6pk]

Originally Posted by selldoor

I should have said check ac voltage on BOTH end of the fuse to the blue cable

Can you post a pic of the bottom of the board?

Both ends of the fuse read 124V

I will get pictures of the bottom of the Board ASAP however it will have to be tomorrow as I have a birthday party for a family member to go to.

[killian6pk]

Originally Posted by tom66

Check your solder joints for the caps. Did you touch up the soldering around the bridge? If not, do this. Seems like there's an open circuit somewhere.

I resoldered all the connections on the bridge and the all the other components I worked on. I also resoldered the Main Transformer legs (on monitors they sometimes are bad). I rechecked the voltage across the Main Filter Cap and it was up to 1.2V after resolderiing it.

Does anyone know what rt stands for on the board it looks like a resistor also what does rv stand for this looks like a glass enclosed Zener Diode but is not the same coloration.

Thanks for the help will be back on tomorrow.

[killian6pk]

Originally Posted by awyatt2

look around the power cord where it plugs in some sets have a fuse on one leg of ac coming in. if it goes you wont get full voltage. i have two sets here with fuses in the connector. a small plastic insert with a fuse underneath, look closely there is a fuse pic etched onto the plastic.all vizios don't have them but some do.i found the first one accidently by removing the plug assy, voltage was right at cord fell at the inside connector.when i had it in my hand i saw the fuse.

Took out the power cord recepticle and did not find a fuse or a picture so I guess this one does not have it. However, after SellDoor told me how to check the voltage on the fuse it is up to standard voltage.

[budm]

Can we see good picture of the bottom side of the power board?

[retiredcaps]

Originally Posted by killian6pk

Also at the same time I changed the caps I pulled the Bridge Rectifier since I had read on another post that it sometimes causes a problem.

What DC voltage do you get on the bridge rectifier? If it is working, it should be around 165V DC.

[budm]

"I also found 3 diodes that read funny when I tested them. So I replaced those 3. I also found one Zener Diode and a 1/4W resistor that I thought were bad and replaced those. One of the diodes, the Zener and the Resistor"
Did you replace those parts with same P/N, rating? A lot of parts to replace at one time.

[Rtech]

Originally Posted by retiredcaps

What DC voltage do you get on the bridge rectifier? If it is working, it should be around 165V DC.

Inside pair AC In ????
Outside Pair DC out ????/

[tom66]

[Post error... please ignore.]

[killian6pk]

Originally Posted by budm

Can we see good picture of the bottom side of the power board?

Here is the picture of the bottom of the board. There are two places where I messed up the pads when I removed components for testing. I scraped off the green carefully and soldered the legs to the copper trace on those two components. I think they are solid. There is also a scratch I made with my iron on the right side of the board. Check that out to see if that might be causing my problem.

[killian6pk]

Originally Posted by budm

"I also found 3 diodes that read funny when I tested them. So I replaced those 3. I also found one Zener Diode and a 1/4W resistor that I thought were bad and replaced those. One of the diodes, the Zener and the Resistor"
Did you replace those parts with same P/N, rating? A lot of parts to replace at one time.

Yes those parts were replaced with part number equivalents from Digikey. I looked up the datasheets to make sure.

[awyatt2]

try replacing the startup cap somewhere close to the 8 pin ic. they dont always read bad esr when in circuit.