RAINBOW COLORS DISPLAYED WHEN PICTURE TUBE BASED TV IS SWITCHED ON. AUDIO OUTPUT IS OK.
This fault is due to its focus pin voltage problem
The
main reason found with this type of problem is with it picture tube
base connecting socket, which is directly soldered to picture tube base
card. The focus pin [Pin number-1] of the picture tube must be noted for
rust or dirt. As voltage
supplied to this pin is high [comes between 2500 to 4600VDC], even a
slight loose contact to the base plug socket will cause ionization which
in turn produces Ozone [by combining Oxygen in the atmosphere], to
molecules of Oxygen (2 * O2) combines at presence of high voltage to
form one molecule of Ozone (O3), releasing one Oxygen atom free. This Oxygen atom at nascent state will be very highly reatable with most material it happens to contact. In short, it will combine with two atoms of Hydrogen to form one molecule of water. This water molecule condenses within the focus contact, casing poor contact within the focus contact, and moisture.
The
fault will be over and the TV will work normally after some time, say
within half hour or so, but it will again arise when the set have been
switched overnight. In the morning, the fault will arise again, and will get rectified itself by half an hour or so.
Although the
fault rectifies and set works normally, it is not good to use the TV in
this condition, as it may cause permanent damage to focus pin, which
will be irreparable. Replace the picture tube base connector socket, soldered directly to the picture tube base card, as soon as possible. Never use the TV when this fault remains.