Screen 'blacks' out randomly.

[flash20]

Recently my iMac late 2009, has developed a rather annoying problem. When using it the screen just goes to sleep - sometimes before I can add my log-in details then on other times I can use it for an 1hr, 2hr or longer before this happens.

When the Mac's screen goes to black I can "screen share" from my other Mac and everything works fine.

Can anyone shed any light on the problem or give me advice on how to solve.

Thanks in advance.

 

[ferrarr]

I don't know if it will help, but could you provide full system specs and Mac OS X/OS X/macOS version of your iMac?

It sounds like there is an issue in the display, and that it is not lighting up. Others have mentioned, shining a flashlight onto the screen, to see if anything is being displayed? It could be a connection, the backlight or something back there?

Have you tried to run Apple Diagnostics, https://support.apple.com/en-us/HT202731?

 

[lclev]

You could give the suggestions in this article I found:

https://www.imobie.com/support/how-to-fix-imac-screen-goes-black.htm

Post back and let us know if it helped.

Lisa