Screen comes on says Acer then No Signal, and goes out. if shut power off and then back on get same result.

This means the monitor believes it's not connected to the computer. Verify the cables first of all. Then try booting in safe mode (F8 key at PC startup) in order to verify that the PC is sending data to the proper video port (you might have a dual VGA / Digital output, for example, and the monitor might be connected to the wrong PC port). Quite often, a "bad signal" will be the same of "no signal"; and you can have a bad signal if the monitor resolution on the PC is set too high. This could happen if you installed a high-resolution capable monitor, and then replaced it with a not-completely-plug-and-play, lower resolution one. The PC would keep sending hi-res signals to a monitor which can neither interpret them, nor tell the PC "please slow down". To check this last possibility, reboot your computer while the monitor is ON. When PCs reboot, they usually drop back to standard VGA signaling, which all monitors understand. If the monitor abruptly comes to life and displays a boot screen, then goes No Signal again after several seconds, you've got a resolution issue; get in Safe Mode with F8 key at boot, and modify the screen properties (right-mouse button on the desktop, then Properties).

If everything else fails, try also connecting the monitor to another PC or laptop, to see if it works there.