SONY WEGA SERIES TVs – POWER SUPPLY FAULTS
KV-HA21M50_ KV-HA21M80_ KV-HA21M80/H_ KV-HA21M81_ KV-HA21P52_ KV-HA14M80 & KV-HW21M83 : POWER SUPPLY FAULTS
Cont:-
Section –2
We have already reached half the way by troubleshooting power supply section. We have found that here is no fault with mains ON/OFF switch, Rectifier Bridge, switching regulator IC, posistor. The
main component to check further is (R610 – 33Kohms 3W) resistor, which
supplies voltage to the internal circuits of the switching IC. This is one among the important test point. Check the voltage at (Pin-4) of regulator IC. If there is no voltage, check this resistor for open. If it is found OK, check the zener diode (D603) for short. Replace it, it is best. If switching regulator IC found shorted, you have to check all the components on the primary side of the SMPS power supply. Even a small ceramic capacitor can cause severe trouble to switching power section.
It
is recommended to use a 100W filament type bulb at the secondary [135]
VDC line, after disconnecting (R502), the serial resistor connected to
LOT power supply. You can
reconnect this after finishing the power supply work. When a set comes
to you for repair, with dead power regulator section, with shorted
switching IC [STR F6707A], be very careful, and check all other
components, for any short, open or any other trouble. Replace
these components, even if they are found good. [C610, D605, R608, R605,
D603&C606]. If power regulation is found poor, check and replace
(IC602 – SE135N) and optocoupler (PH600). If
STR are is found shorted, you have to replace all the above mentioned
components, otherwise the newly replaced STR may get fail, as soon as
you switch ON the set.
Check all the solder terminals of SMPS transformer, and other components for loose soldering. This is the main fault for most of the Sony set. Resolder
all the suspected solder points by applying a little more solder,
without making any solder bridge short in between adjacent solder
points.
