The
set received for repair in dead condition.
There was no Model number or any other details, nowhere on the set or
its inside.
The
power LED at its front panel lights up; upon switch it ON, and goes ‘dim’
immediately and shows fluctuations in its intensity.
An
“Ish, Ish, Ish” noise is heard form the SMPS side circuit of the set.
No
audio thumb, no video or filament of the CRT do not glow.
Checked
the voltages out from the SMPS.
All
the output voltages were OK; except +B111VDC.
It measured at about 81VDC, and is fluctuating.
The
Horizontal scan output transistor overheats too.
Clear
evidence to damaged LOT [Line Output Transformer].
De-soldered
out the horizontal output transistor, and checked it with multi-meter set to
Meg-Ohms range.
No
abnormal measurements detected.
Un-soldered
out the LOT.
There
was no number sticker on it.
Without
its number, it will be difficult to get from the electronic spare part market.
I
called the party, and asked them to buy it from anywhere.
He
has bought one.
The
number of the new LOT he bought is [TF-0107-OU
BSC 24-01-40] Might be a Chinese make.
Not
sure; whether it is the original number or not.
I’ve attached the photo of both the LOTs here.
CLICK ON THE PICTURES TO ZOOM IN
Replaced
the LOT and HOT [Line Output Transformer & Horizontal Output Transistor]
Checked
all the other components by following its schematic. The main board to this TV is shown here. As there is no model number, that I can see
anywhere in the set, I did follow a schematic using the main system control
chroma jungle IC TDA9370PS; as in this main board too used the same.
No
other problems detected.
Connected
to AC mains; and switched it ON.
There
is no raster at all; but the CRT filament is glowing.
Checked
the +B voltage; once again. OK.
111.5VDC.
As
the LOT is a new one, the screen volt pot-meter of it was set to extreme left
[Minimum].
Advanced
the pot-meter, till the raster came up.
Kept
it at this condition for about 10 minutes.
Switched
it OFF; unplugged it from AC mains socket, touched the heat sinks of both SMPS
drive transistor and the Horizontal Scan Output transistor.
The
heat at HOT heat-sink was normal; but it was abnormal at SMPS drive transistor.
A
slight overheat felt to my fingers. At
the same time, when I switched it ON; a very feeble high-frequency noise was
there coming from the SMPS transformer. It shouldn't be so. Must be so silent. I did suspected the windings inside this transformer for a while, but it
was not.
When
I touched the +B voltage smoothing capacitor, 100MFD160VDC, it was too hot. It shouldn't be so. Must be cool.
I
de-soldered it out from the circuit board, and tested it for capacitance. Shows only 30MFD. Checked its electrolyte leakage
resistance. Shows only 135Ohms. This capacitor is damaged. We can say it to be leaky. Just see, there was no bulging on this
capacitor; yet it is damaged.
Replaced
the capacitor with a new one of same capacitance.
Switched
ON the set, and tuned in to an on-air program; after connecting it to external
antenna.
Auto-tune
function is OK. Tuning memory lock is
OK.
But;
some color patches are at the screen.
Replaced
the de-gassing posistor; as it might be the possible reason. Yes.
It was.
Checked
the set. OK.
MAIN BOARD
THE COMPONENTS I DID REPLACE
PICTURE - AFTER REPAIR
The
party has lost its original remote control and thay have bought an other
one. It works fine with this Tv. I’ve attached its photo here.
It’s
a TUSCAN VSA 3-IN-1. It can be used with
3 brands of TVs. Videocon, Sansui &
Akai.
You
can select the brand of your TV. There
is 3 separate selector buttons are there at this remote control [at the bottom
right side of it].
Just
see it.
