Monitor or keyboard working emachine

I have an emachine t3508 about 2 years old, and it all of a sudden stopped sending signals or power to the monitor and keyboard. I have changed them both out with ones I know work and the lights dont come on , on the keyboard, and when the monitor comes on it says no input signal. The pc comes on an the fans are going, the light is on, but I get no "beeps" and the monitor stays black. I cant check the mouse or any of the other ports back there, cause without the monitor working,,its futile lol any help would be wonderful! I have read a few places, maybe its the graphics card, but would that effect the keyboard? I think somehow its the pannel maybe, but not sure how to check, or where to check.

 

Emachines usually have a Bestec power supply
Bestec power supplies are est known for suddenly failing & frying the motherboard in the process.
The thing is , it still appears to work after failing.
The fans will spin & give the impression the power supply is OK.
Bestec power supplies have given emachine a bad name but they are still used !

You should try a known good power supply.
If the computer still doesn't come on the motherboard is fried.

 

Thank you so much for responding! It does seem to me to be a power issue, I'm more of a software person than a hardware person but I'm learning lol But I didnt think it was the whole power supply, cause like you said the fans were still running an the mother board green light is on, and the pc turns on. My husband does hvac an electrical and has a meter to check for ( volts/amps? lol) I'm going to have him test it, is there a transformer or something near the power supply that he should test? or something near the rear where the ports are? I have 3 other towers I can take the power supplies out of , but 2 are compaqs, an one is a dell an this is an e machine lol I tried to get the skematics from emachine tech an that was futile at best lol Thanks for the help too, Im sure you have more things to do than to sit an help hardware impaired moronians ( new word for webster lol) like me, but any additional help is welcomed as well! Thanks Wendy!

 

When it comes to a fried motherboard there really isn't a lot to test.
You hook a good power supply to it & it either works or doesn't.

BTW, I have fixed many emacines with the same problem.
From my expierence there is a 50-50 chance that the motherboard is still good.

 

crossin my fingers ty so much!