Why will my screen not turn on?
when I turn on my imac I hear the chime and the crt but it displays nothing
Take the back off and examine the capacitors for swelling and/or leakage.
Next step would be to go over the video board with a soldering iron looking for “cold solders”.
You can get a very good electrical jolt from the CRT so look up how to discharge it.
Nevermind, here is a video on how to do it: