IBM 5151 dim/unfocused picture

[cwathen]

My 5151 seems to have developed a fault. The display brightness has suddenly got very dim and is losing focus.

At max resolution/contrast it's just about bright enough (although nowhere near as bright as it should be at max settings) but the display is then looking blurry and unfocused at that setting.

When the controls are dialled down enough for the display to look sharp its then very dim and not comfortably usable except in a darkened room.

Hopefully this is tired caps somewhere and not the CRT on it's way out?

 

[Stone]

Could be the CRT or even the flyback.

 

[KC9UDX]

Most likely not the tube. Most likely the flyback. But other components can cause this, too.