Vizio Power Supply Schematic or Repair Assistance

[mrtweaver]

Working on a Vizio VP322HDTV10A. Power supply PSPU-J707A. The following capacitors were popped up: C233, C234, C236, and C201.

Replaced these capacitors, powered on board, if left powered on C201 overheats and lets the magic smoke out. SO there is still a problem. But without schematics not sure what section to look at.

Thought maybe someone on here would have experience with this board and be able to point me in the correct direction.

Thanks and have a great day.

[timescope]

Hi mrtweaver, I did a Vizio supply two months ago that had a shorted schottky diode . Multiple damaged capacitors would suggest a loss of voltage regulation so you should check the voltage feedback loop.
Brief explanation: The power supply is divided into two parts,the primary side that connects to the power plug and the secondary side that connects to the electronic circuits inside the tv.Both are isolated from each other by the transformer and opto- isolator ( a small ic with 4 pins).A sample of one of the output voltages is used to drive the opto-isolator which controls the pulse width of the switching regulator on the primary side.
You should try to locate these circuits and check the components.
I usually use a 60- 100 watt light bulb in series with the live mains wire when working on supplies to prevent damage.Take care as the voltages on the primary side are DANGEROUS.
timescope
_________________
We never appreciate what we have until we lose it.

[Guest]

So you dont have a set of schematics for this board then I take it?

And you say the Schottky was shorted. You dont happen to recollect the part number on the board do you? Ex:C201, ZD203, R204, etc..

Here is some additional information on this, comming off of transformer T201 which is a multi tap transformer, there is a diode D201, this diode goes thru jumper J50 which in turn goes to cap C201, the voltage across C201 is 21 volts with J50 in place and burns out C201 if left on for to long. C201 is only rated to 10V.

Now if I remove J50 and measure the voltage comming from D201 it is only 10.5 to 11 which is well within tolerance for C201. So somewhere the extra voltage has to be fed into the circuit. But likewise measuring the voltage at C201 with J50 remove I get zero. I know it has to be something down around in that area but thus far I have been not very successful in finding it. I also have been unsuccessful in finding schematics for this power supply.

Thanks and have a great comming holiday.