Black display when toshiba 40e210u is power on

For what?

Sounds like main board fault. Contact any service technician to confirm. If you wish to get some details; check the site linked here. Viewing it in "Mosaic" or "Magazine" will make surf easy Pull up older posts. Surf the site with patience.
http://electronicshelponline.blogspot.com/

I am confused wit the question. Mono is an audio setting. And video setting are for just that. video.

Unfortunately, not all Toshiba TVs have a headphone jack, The 40E210U is one of those models. The above referenced model only has digital audio out. You would need a digital to analog audio converter and then RCA stereo to 3.5mm adapter to plug in most headphones.

You can always look on the back and side of your TV and look for a 3.5 mm port with a headphone symbol. If you have a different model, many Toshiba product manuals are available here: http://www.csd.toshiba.com/cgi-bin/tais/support/jsp/home.jsp . Click on Product Support and then use the drop-down menus to select your product. Then click on the GO! button and choose the User's Guide tab.

I wish that I had better news for you.

Cindy Wells

Video display card could be bad but I wouldn't rule out the power supply just yet. It breaks off in several directions and the lead going to the display driver could be bad. Put a meter on it to see.

I would start with having the power supply checked. If the power supply is in good working order, I would then suspect the main board.

The Aspect ratio of the TV could be on the wrong setting for the image you are trying to view. Widescreen's standard ratio is 16:9 ensure the TV is not set to zoom, 4:3, or pan & scan in the picture menu of your TV.

If the picture looks normal except it's just missing the edges or looks squashed or looks like it is zoomed in from the normal image then aspect ratio is probably the cause.

The SMPS or inverter is switching on and off, possibly due to leaky/dry capacitors or dry solder. This is a case to be looked into by a qualifies service technician.

If you keep getting this problem(green light turn on for 5 to 10 seconds then TV shuts down along) you get to try this:
On ebay seach, type in "40E210U dead" there is one solution, good luck!

Consider having it repaired as it should be in warranty.