Vizio M550SV No Power/Lightning Strike

[gideon277]

This tv only has two boards the Power Supply and the Control or Mainboard. (My volt meter died so will be testing voltages later) I did conduct a thorough visual examinations of the boards and they appear to be fine. I checked continuity on all fuses and they tested good. The Vizio LOGO on the front of the television does not come on while plugged in which suggests to me no stand by power.

[nomoresonys]

Re: Vizio M550SV No Power/Lightning Strike

if you have a digital multimeter, check for expected voltages on connectors/cables going to the other board, see the legend/label, next to the connectors? check stby first, report any that are not as marked on label, as always be careful working with power supply, HIGH VOLTAGE, on primary side can be deadly.

[budm]

Re: Vizio M550SV No Power/Lightning Strike

Check the main AC fuse (white fuse with red band), if it's OK then check the DC Voltage right at the two legs of the main filter caps (68uF 450VDC) to see if it has 160VDC (you must have this voltage before going any further), be real careful not to slip the probes and do not touch anything with your hands.

[nomoresonys]

Re: Vizio M550SV No Power/Lightning Strike

looks like theres another fuse there by the filter caps too.

[budm]

Re: Vizio M550SV No Power/Lightning Strike

I believe that fuse is connected to the output of the PFC Voltage circuit to feed the man power supply section.

[gideon277]

Re: Vizio M550SV No Power/Lightning Strike

Continuity on both of the fuses checks out as good. I am getting 6 volts on in of DC fuse the one by the power connector. This is when the set is plugged in. Of course when power is pressed absolutely nothing happens. All standby numbers look fine.

[nomoresonys]

Re: Vizio M550SV No Power/Lightning Strike

ok, did you check all expected voltages on power supply?, should be labels by the connectors.

[nomoresonys]

Re: Vizio M550SV No Power/Lightning Strike

Check the main AC fuse (white fuse with red band), if it's OK then check the DC Voltage right at the two legs of the main filter caps (68uF 450VDC) to see if it has 160VDC (you must have this voltage before going any further), be real careful not to slip the probes and do not touch anything with your hands.

also did you test this?

[budm]

Re: Vizio M550SV No Power/Lightning Strike

Continuity on both of the fuses checks out as good. I am getting 6 volts on in of DC fuse the one by the power connector. This is when the set is plugged in. Of course when power is pressed absolutely nothing happens. All standby numbers look fine.

Where did you put the black probe of your meter?

[nomoresonys]

Re: Vizio M550SV No Power/Lightning Strike

when checking the connectors black probe goes to ground ether chassis or a screw, etc.

[gideon277]

Re: Vizio M550SV No Power/Lightning Strike

I keep the black probe on the ground wire that goes to the chassis by the main power plugin. There are two caps side by side which cap are you referring to? At any rate on the right leg of each of those caps I get the same reading for 67.1

[budm]

Re: Vizio M550SV No Power/Lightning Strike

When you make the Voltage measurement in the primary (hot) side of the circuit, you must use the negative leg of the main filter cap and the GND ref. for your meter.
When making Voltage measurement in the isolated secondary side of the circuit, you can use chassis as the GND ref, because the Isolated secondary side power supply circuit GND is tied to the chassis.

"At any rate on the right leg of each of those caps I get the same reading for 67.1" That is why you get that wrong reading of 67V.

POST #3: "if it's OK then check the DC Voltage right at the two legs of the main filter caps (68uF 450VDC) to see if it has 160VDC" That is why I gave the instruction to measure the Voltage RIGHT AT THE TWO LEGS OF THE CAP.

Please follow the instruction carefully since wrong readings will make it very hard for us to troubleshoot the problems.

[gideon277]

Re: Vizio M550SV No Power/Lightning Strike

So red probe on right leg and black probe where?

[drussell]

Re: Vizio M550SV No Power/Lightning Strike

So red probe on right leg and black probe where?

To the left leg....

One probe to each leg of one capacitor...

You are trying to measure the voltage that is being applied to that capacitor.

[budm]

Re: Vizio M550SV No Power/Lightning Strike

"right at the two legs of the main filter caps (68uF 450VDC)"

I can see that this is not going to be easy for me after 12 posts.

[nomoresonys]

Re: Vizio M550SV No Power/Lightning Strike

[nomoresonys]

Re: Vizio M550SV No Power/Lightning Strike

[gideon277]

Re: Vizio M550SV No Power/Lightning Strike

Alright, wow I just had a brainfart moment. Take it easy I'll post voltages later this morning.

[gideon277]

Re: Vizio M550SV No Power/Lightning Strike

Okay on my auto sensing volt meter I get 326vDC on each of the caps. My meter is autosensing.

[budm]

Re: Vizio M550SV No Power/Lightning Strike

That does not look right, disconnect the cables between the main board and the power supply board and recheck that Voltage on the cap again, it should have only around 160VDC.