All of these sets had bad picture tubes--the tubes are no longer
available--can only be got on a rebuild basis--very expensive----Blue
tube seems to be the most common to go bad.
If the screen goes bright blue the set will shut down as the set detects too much current is being pulled by that tube--
than replacing the tube you do have one option that may resolve your
problem--it may return the set to operation----it also may just only
buy you some time.
These sets have a black plastic block located
behind the front speaker grill--there is a inspection plate behind the
grill and behind it is the square black plastic block with 6 controls
molded into it----it is the Screen/Focus block.
I can tell
you how to get at it---what you want to do if you do this is get the
grill and inspection plate off and locate the block.
There will be two rows of 3 controls---one row will be marked Focus---do not touch those.
The other row will be marked SCREEN---you have to look very close to see which is red, green, blue.
With the front grill and inspection plate removed you turn the set on----have it on a Video input
with nothing connected to it---if you locate the Blue screen control
you turn it to the left until you do not see blue or curved blue trace
lines---if you turn it the wrong way the set will shut down---
you get the blue set---look at the screen on the blank input---you
should only see the video input display---if you see some green or red
you need to adjust those controls also.
Understand--even if this
works--you may only be buying some time--if one of the tubes caused
this sooner or later it may happen again.
Let me know if you have questions or need advice.
I am here to help people.