When the get old, that just happens, and I don't know of any way to fix it permanently.
I know this sounds terrible, but the only way I can get them to brighten for a while is to whack (not to hard) the top or right side of the CRT.
***DO SO AT YOUR OWN RISK!!*** (and the crt's)
crt monitor situation used
CRT stands for Cathode Ray Monitor. These monitors have a glass screen.
It is cheaper than a LCD monitor.
The monitor was a 12" CRT.
Advantages_and_disadvantages_of_crt_monitor
It's a CRT which stands for Cathode Ray tube.
CRT Monitor
gandu
They are cheaper.
You can get them for free.
If you're think to put an ad for your CRT monitor for free, then you should consider listing it on your local Craig's List.
CRT stands for Cathode Ray Tube. In laymans terms a CRT monitor is the old-style glass tube monitor we all used for years and years before flatpanel monitors became cheap & popular.