check the heater voltage is not low.
if its dc volts check the filter cap
on that rail, had one like that years ago
with leaky electro cap.

"Martik" wrote in message
news:cuFmg.68532$I61.55234@clgrps13...
Samsung 750s approx 5 yrs old, text is ok but video and jpg's are too
dark. There are two adjusting 'screws' on the transformer but BOTH are for
focus. The only other adjusting screws I can find are on the neck marked
Yv Yh Yhc.

Here is a pic of the 2 adjusting screws on the transformer. The one on top
cannot be turned.

http://www3.telus.net/shared/Monx.jpg