This could be a heater-cathode (H-K) short in the CRT, a failure of a
component in the chroma circuits or video output (driver board), or bad
connections there or elsewhere.
Don't panic - heater-cathode shorts in CRTs can often be worked around.
Note: before proceeding, it is a good idea to make sure that the screen is
degaussed - else you could be attempting to track down problems with the wrong
Some simple tests can confirm or rule out other possibilities.
- Compare the voltages for the video drive signals to the CRT on the little
board on the neck of the CRT with the CRT both connected and unplugged.
A schematic will help greatly in locating these signals.
- If there is a significant difference especially on the bad color, then the
CRT is a likely candidate. Try tapping the neck of the CRT GENTLY (with
it plugged in and while viewing a picture) to see if it is an intermittent
- If there is no significant difference, you may have a bad driver or a
problem in the chroma circuits.
- Look for bad connection/cold solder joints, probably on the little
board on the neck of the CRT. Use an insulated stick to gently prod
the board and its components in an effort to induce/cure the problem.
Look carefully for hairline cracks around the component leads.
- You can swap components between two colors and/or test with an ohmmeter
on that driver board to determine what is bad. The nice thing about
color monitors and TVs is that there three copies of each of these
components. Swapping and/or comparisons between these is an excellent
- Another simple test: Disconnect the cathode for the full-on color from its
drive. If it is still full-on, there is probably an H-K short in the CRT
since the only way to get each color on the screen is via the cathode
connection to the CRT neck board. If it is removed and there is still that
color, the current must be taking another path inside the CRT.
- Alternatively, interchange the outputs of the bad color with a good one
by jumpering on the video driver board (on the CRT neck). If the bad
color changes, then the problem is in the circuitry and not the CRT.
So you have to get a tech if the above method doesn't solve your problem and get it fixed..
Please don't forget tor ate me as fixya..