VERTICAL LINE PROBLEM - CRT BASED TVs
VERTICAL LINE AT THE CENTER OF THE SCREEN STRAIGHT DOWN
This is a very rare case to color
television. A single vertical line
through the middle of the screen, sound OK.
Horizontal scan output failure is the reason. Here, all the other sections of the TV
circuit are functioning well and even the horizontal scan output section
too. If not, the fly back transformer
does not function, there will be no EHT, and will be no light. As we see the line on the screen, we can
assume that something wrong at the path of horizontal scan output section, to
the horizontal scan output winding section at the deflection yoke.
The first thing check is to test
the continuity of the horizontal deflection winding. We can check it using a multimeter, set to
Ohms rage. In most sets, the resistance
to this winding section will be in between 1.8 Ohms to 2.6 Ohms. If the meter shows no continuity, make sure
that the winding is open. There is no
repair other than replace the deflection yoke in this case.
If the deflection yoke seems to
be OK, check the solder terminals of the pin connection at the main PCB [P401],
to the deflection yoke. In most cases,
this might be the fault. So, check all
the four connections to this socket, and re-solder all of it if needy.
Check the solder terminals of [C401: refer circuit diagram] too. If this capacitor is open, or have loose contact at any of its two solder terminals, the horizontal output signal path to ground will be open, so vertical line will be the result.
Check the solder terminals of [C401: refer circuit diagram] too. If this capacitor is open, or have loose contact at any of its two solder terminals, the horizontal output signal path to ground will be open, so vertical line will be the result.
If the deflection yoke has
shorted winding with horizontal scan section, there is no doubt, that the
horizontal output transistor will get damaged due to overheating; as soon as we switch ON the set,
and sometimes, there will be smoke come out from the deflection yoke. In this case too, deflection yoke should be
replaced. But, failure to deflection
yoke is rare, about 0.01%.
There are no more reasons for
this fault ‘vertical line’. If the
horizontal output transistor is damaged, there will be no light at all to any
cases.
The horizontal output section
circuit to JVC21JT 5EU is shown here for reference.
