Screen Is Very Dark

[petecal]

Sometimes my RPi screen is very dark. Not black but very dark.
It happened yesterday and thinking it was the controls on the monitor I tried brightness, contrast but nothing helped. So I rebooted and everything was fine.
Today the screen was dark and I had to reboot twice because the first attempt came up dark again.
Tonight I can't get the screen back to normal no matter how many times I reboot or shutdown and restart.

The screen is dark from the very beginning. The rainbow screen is dark but visible. Same for that screen with the raspberry image. When the dump listing all the startup stuff scrolls it is barely visible.

After the desktop appears just that bright sun part of the image is visible. The rest is very faint. I can see the task bar and if I can guess at the cursor position and open the file explorer, then I can read the folder and file names on the white background but that is about all.

Any ideas what i should do?
Thanks,
Pete

[topguy]

Sound like something with the HDMI settings.

Which model of Pi ?
Which operating system is installed ?

[petecal]

I used NOOBS so I guess it is Raspbian.
I also have a HDMI to VGA adapter.
But this setup has been working since January (~9 months) without this problem.
Two days ago a single reboot fixed the problem.
Yesterday a took a couple reboots.
Now nothing helps.
Is there a Settings somewhere?

RPi 3 B

[wolf.z]

Good grief, could be one hardware issue out of the following:

Loose connection either adapter or cable
Near full cable break, but not yet full
Soon to die backlight of monitor
Soon to die power supply of monitor

So, if available try a different monitor and adapter, best just another HDMI monitor without adapter. Take your Raspberry to a friend or at school or at work or...
If that works, narrow the origin of failure.

[petecal]

If I remove the VGA cable from the adapter the screen goes full brightness so I think the monitor is fine.
If I remove the HDMI from the Pi the screen goes black. Then when I plug it back in the pi it stays black until I tap on the keyboard. Then it returns to the dim image.

I plugged the HDMI connector that was in the Pi and plugged it into a computer. Perfect picture. But if I wiggle the VGA connector at the monitor I see all kinds of blinking and flashing. I decided it was the VGA connector on the monitor. I opened up the monitor and touched up the solder connections on the VGA connector. They didn't look bad but I didn't know what else to try. I hooked the cable back in and, everything worked.
Reassembled the monitor and all is well.

But I wonder why rebooting fixed the problem (at least) three times.

Thanks.