iMac 27" late 2009 - Black screen

[Makboy]

Hi, I got an iMac 27" Late 2009, I've been using it every day for almost 10 years 24/7 turned on.
Last month suddenly when I reseted to log in Windows I got a black screen, I hear the usual chime but then a black screen after that (in other words, the computer remains "turned off" and not showing the usual white screen with logo), I thought it was the death of the iMac but after a few resets I could get the white screen to load the system normally, but it is getting more and more complicated on each reset -i.e. a month ago were only 4 or 5 resets, this morning were about 30!-, I've called to Apple store and they told me there could be a problem with either the display or the backlight, beside that they won't repair this old iMac.
Could be a backlight issue? I don't have any kind of black "clouds" when I use the computer normally, the screen looks fine as new, the problem is each time I reset the computer I got a full black screen, the system loads fine, it is just a display issue.
They advised me to plug the computer in an external display but haven't tried yet. (I don't have the HDMI cable).

The question is if I don't see any "black clouds" and the problem appears on each reset, could still be a backlight problem? so changing the LED backlight could work?
Like on this post?
www.ifixit.com/Guide/iMac+Intel+27-Inch+EMC+2390+LED+Driver+Board+Replacement/9264

 

[oVerboost]

What info did Apple have to guess it was the backlight?!

I would try plugging in an external monitor and using that to see if the problem persists (external monitor as a main monitor).

 

[Makboy]

What info did Apple have to guess it was the backlight?!
.

they were just guessing by phone, and advised me to do the external display proof as well, but I'd need to get an HDMI cable. Just wanted to know if the backlight might be the problem before buying the cable. I mean, if I not necessarily have to have the black clouds spread over the screen to confirm it is a backlight problem. When I use the computer the screen works perfectly, no flicker etc., the problem only appears if I reset the computer.

 

[oVerboost]

May be a daft question, but what brightness do you have the screen set to? Try maybe setting it to low brightness next time you manage to get into the system.

 

[Makboy]

May be a daft question, but what brightness do you have the screen set to? Try maybe setting it to low brightness next time you manage to get into the system.

between 3 and 4 little bars only, already low, I don't think that will be causing the problem though.

 

[Fishrrman]

It could just be that after 9 years of being powered on 24/7, the ol' iMac is gettin' ready to "give up its ghost".

Might be time to start thinking -- just thinking -- about something newer...

 

[Makboy]

It could just be that after 9 years of being powered on 24/7, the ol' iMac is gettin' ready to "give up its ghost".

Might be time to start thinking -- just thinking -- about something newer...

yes I know, at this time she probably hates me with all her hearth but if there is any chance to fix it I'd do it, it will also help to sell it to somebody else working instead of having to sell it as spare parts cheaper, if you know what I mean.