TV LCD REPAIR
Brand : SABA
Model : KU 22A200
Fault : Dead
This device is a LED back lighting system TV of recent
production.
To be precise it’s a “combo”” with incorporated DVD
player bought by the client 2 years ago….guarantee just expired.
Made in Turkey
In respect of other devices in this category, opening
it was fairly easy.
The screws to be removed are signalled by the arrows but it also needed a fair
amount of manouvering.
To avoid damaging the device while opening it I used a
yellow plastic spatula seen in the foto.
Once opened,I saw that the panel and boards were only
resting on the front cover.
During testing, to avoid eventual breakages I tried to
keep the device in a horizontal position, resting it on a soft panel.
The DVD section was screwed onto the rear cover.
The first measurement
tests were very rapid and fairly easy without removing the boards.
The rectified net voltage is present on the long smoothing caps.
I found no voltage on the cathode diodes found on the
secondary PSU exits.
After removing the net cable i checked for short
circuits on these exits.
I found the diodes D708-709-710 short circuited.
I removed the PSU board.
Between the three
parallel diodes, I found a short circuit on D 709.
I replaced it during testing with a BY399, obtaining
positive results.
I had no original diodes SB5100 in stock. These original diodes are capable of
sustaining major current.
I immediately ordered this spare part and once it was replaced i took the device back to the
client.
This fault is typical on this type of chassis but the
diodes on the secondary section of the PSU are a weak point also on other TV’s,
especially small ones.
In general we could say these weak points should be always checked on
all S.M.P.S.
