NES will not power on (no red light)

[treismac]

I was given 5 non-working Nintendo Entertainment Systems today at the flea market by a vendor. 3 of them just needed their 72-pin connectors cleaned, but 2 of them won't even flash a red light when I push their power button. The problem is definitely not the power adapter as I used the same one for all 5 of them. When I press the power button the tv acts like "something" (a nearly insignificant audio pop and brief, faint horizontal line flashes) happened but the screen remains black. A little research has uncovered this webpage (http://www.ifixit.com/Wiki/Nintendo_Entertainment_System_Troubleshooting) that states:

"You know that your DC-in board is bad when the game console will not power on. The only way to resolve this problem is to replace the DC-in board."

Does this seem likely/plausible?

[ApolloBoy]

That guide reads like it was written by someone who has no experience with fixing NESes. Replacing the entire RF/power board is completely unnecessary, I'd just try replacing the 7805 in both since they refuse to power on.

[treismac]

Replacing the entire RF/power board is completely unnecessary, I'd just try replacing the 7805 in both since they refuse to power on.

Awesome. Thanks, ApolloBoy!

The 7805 is the 3-pronged small black box with the screw above it, right?

https://scontent-a-iad.xx.fbcdn.net/hphotos-ash3/t1/p180x540/1900124_10153920979255294_661775304_n.jpg

EDIT:

Yeah, that has to be it (http://www.radioshack.com/product/index.jsp?productId=2062599).