Where is the 10V 3300uf capacitor located on the optoma hd66 power board?

It will be difficult to get. If the space allows, you can use 3300MFD 16V capacitor in place.
Electro help

Most common cause is Bad Capacitors on the Power Supply Board, they will be swollen or vented on Top. 1000uf 16v 2200uf 10v 3300uf 10v 220uf 10v 330uf 10v these are some of the values of capacitors that go bad.
You can go to Shopjimmy.com and type in your model number to see if they have your boards in stock. Thank You

replacing the 10V caps with 25V caps is perfectly fine. In fact, if it was manufactured like that, those caps may not have blown.
Replacing a 680uF with a 1000uF could be problematic depending on it's function.
680uF is pretty specific when 500uF and 1000uF are much more common and therefore cheaper - one would think that the engineers would have tried using those in the design rather than a 680uF - makes me think the value of the cap is important to the frequency of the circuit it's in.
Other concerns might be whether he got any of them in backwards or not.
That's a rookie mistake, but still an easy enough one to make (for a rookie).
Also, with that many swollen caps, I wonder if there were any that leaked out the bottom before swelling at the top (IE - if some caps were missed in the replacement procedure)
Also, with that large a number of caps gone, other components may have been compromised or blown.
I'd be testing the transistors around those caps (most likely punched through rather than open), looking for fusible links (surface mount fuses, 0 OHM resistors) that may have opened up etc.
The initial attack on the problem was basically correct, and in many cases probably would have fixed it (if say the 680uF cap was functioning as a ripple filter).
But when that didn't fix it, a deeper analysis should have been done to complete the repair (including locating a 680uF cap).

You need to check on the power supply board for Bad Capacitors they will be vented,swollen, or puffed up on Top. 680uf 10v,330uf 10v 3300uf 10v 2200uf 10v,

Plasma? Your power supply has bad capacitors. 3300uf most likely. This is a common problem on some Philips plasma TVs. Power board is located top center of the TV with the rear access panel removed. look toward the lower left portion of the board. If you notice any capacitors (they look like little plastic wrapped cans) with swollen tops or leaking dark fluid from the top of them, replace them. Myself, I always step up the voltage rating... ex: 3300uf, 10v -> 3300uf, 16v.

The short answer is no. You can replace a 3300uf 10V cap with a cap of similar value but a slightly higher voltage (3300uf 16V or 25V).

Changing the capacitance value will significantly alter the circuit. Please note that the value listed suggests that it is a component in the power supply, specifically a filter cap.

Dan

Try this:
There is a stuffed 10v 3300uf capacitor on the power board. You need to replace it.
Bellow you can check in the picture where the capacitor is located.

Notice that in this picture I have already took the bad capacitor out and replaced with two small cords to reach the bottom and test the new capacitor.
To reach this place is not fast, several layers of plastic and metal must be removed, but is not a hard task to take the capacitor out and replace it for another.
It works just great! Now it is back on track with awesome image.

Try this: There is a stuffed 10v 3300uf capacitor on the power board. You need to replace it.
Bellow you can check in the picture where the capacitor is located.

Notice that in this picture I have already took the bad capacitor out and replaced with two small cords to reach the bottom and test the new capacitor.
To reach this place is not fast, several layers of plastic and metal must be removed, but is not a hard task to take the capacitor out and replace it for another.
It works just great! Now it is back on track with awesome image.

There is a stuffed 10v 3300uf capacitor on the power board. You need to replace it.
Bellow you can check in the picture where the capacitor is located.

Notice that in this picture I have already took the bad capacitor out and replaced with two small cords to reach the bottom and test the new capacitor.
To reach this place is not fast, several layers of plastic and metal must be removed, but is not a hard task to take the capacitor out and replace it for another.
It works just great! Now it is back on track with awesome image.

Try this: There is a stuffed 10v 3300uf capacitor on the power board. You need to replace it.
Bellow you can check in the picture where the capacitor is located.

Notice that in this picture I have already took the bad capacitor out and replaced with two small cords to reach the bottom and test the new capacitor.
To reach this place is not fast, several layers of plastic and metal must be removed, but is not a hard task to take the capacitor out and replace it for another.
It works just great! Now it is back on track with awesome image.