IMPORTANT: WHILE
WORKING WITH TV OR ANY CIRCUIT WITH HIGH VOLTAGES IT IS WISE TO USE AN
ISOLATION TRANSFORMER FOR YOUR SAFETY! (I need to buy one soon!!)
TYPE: KS1A14E4
MODEL: CZ-14E4V
SYMPTOM: PICTURE SQUEEZED IN AND DIED - BURNING SMELL
Well, you are enjoying your favourite tv show, and suddenly the picture starts to squeeze in and before you could respond logically, the picture has gone leaving behind an odour of burnt insulation.
DIAGNOSIS:
-The
symptom indicates the deflection yoke coil failure. Make sure by finding traces
of burns on the coil, you can even smell to confirm. And technically you can
measure the coil resistance to find if it has shorted or opened up! The picture
below elaborates my case-
-Yoke failure confirmed with badly burnt HORZONTAL DEFLECTION
coil/LINE coil. The resistance test confirmed a short. As I was trying to figure out the
reason for the same, found dry solder joints on the connector where the coil
was soldered. It is wise to resolder these points once the problem is in its
initial stage and thus the fault can actually be avoided. Use a high wattage
iron (around 55W) for good soldering finish. This in necessary as the coils
draw high current (also at high frequency, 16kHz approx. in the case of line coil) and hence the solder joints can dry up easily! This can
also affect the horizontal output transformer (HOT) and associated circuitry.
-Replaced the deflection yoke with a new one from the market
(₹250). Before replacing
the yoke, please make sure you mark the positions of the purity &
convergence magnets on the CRT neck with a marker or whatever you prefer. Even
slight changes to the original positioning could effect the picture quality (I
was very excited to replace and didn’t think of it much and later on had to
toil hard to bring back into its earlier position, though is not perfect). Checked
the circuits nearby only to find everything quite fine. Switched ON the set and
the picture was back!
-Note here that the new yoke coil is not completely in tune
with the circuit elements of the tv and as such the new yoke may introduce
convergence/geometry/landing errors. For eg, the new raster could be wide or
narrow (in my case it is wide). Havn’t gone into the details of improving it
yet. A short cut to it would be to adjust the settings by entering the FACTORY/SERVICE MODE of your tv (just be careful while changing the settings there). Different
tvs have different keys to enter the factory mode which could be googled! But it
won’t solve the problem completely. Infact the raster size could still be different
for different channels.
