Videocon
CTVVSF21 SDA-CFS – 21” FLAT CRT TV. Chroma IC used: TDA 1213PS/N3/3. Memory:
K24C08C. Standby LED lights up, set
powers On when the power button at the remote control is pressed. But no Raster; Audio OK.
The
party said that they were seeing this set; after being done a ‘Hit’ at the top
of it, since a year. According to them;
when they do this, the set will work alright for that day, but overnight the
fault re-appear.
It
is rather difficult to locate a loose solder terminal than normal
troubleshooting; because, these defective solder contacts will be very
microscopic,[normally] in nature, that we can’t detect it with our naked eye.
I removed the back cover of the set.
Powered
it up.
The
standby LED began to glow.
Pressed the power button on the remote control.
The
standby LED powered OFF, indicating that the main board is now powered up.
No
indication of EHT generation.
No
unusual noise from the main board; other than the normal “Hizzzz=” sound from the loudspeaker.
Fed
the external antenna. The audio of a
local station heard. The audio is OK;
no distortion at all.
I
pressed the Volume Up button at the remote control. OK.
The volume increases.
Means,
Tuner, Video IF (VIF); audio processor, Main system control section Micom, audio output & speaker are OK.
Should
check the LOT {EHT} section circuit.
Loose solder
terminal/s at the circuit board. But
where? It is the problem.
Switched
OFF the set.
Disconnected
the Ariel, and pulled the PCB out from the set.
Placed it in a position that I could see the print (foil) side of the EHT
section circuit.
Powered
it ON.
The
standby LED glows.
Touched
the Prog+ button at the control panel at the side of the set.
The
standby LED turned OFF after about 2 seconds; indicating that the set has
powered up.
Aahh!!
As
soon as the set powered ON, I did see 2 solder terminals of the EHT transformer
are arcing. I’ve attached the photo of it here.
LOT pins marked, ABCL & 180V have cracked solder terminals. You can notice it, if you magnify the above picture. Just click over it.
De-soldered
out the solder from all terminals of the LOT, and re-soldered all of it by applying
fresh solder.
Switched
the set On. OK. Picture is there. No further adjustments needed. It is very clear.
This
seems to be a general fault to most of the TVs nowadays, irrespective of its
brand and model number. But haven’t
noted much cases Sony and Grundig brand sets.
Especially, when the climate changes from Hot to Cold; this type of
fault too will be frequent. Here; where I live, the Monsoon have started by day before today. Since then it was summer. What else be, this type of fault can occur at
any time, I assume.
Here
I got the exact faulty solder terminals very easy, as there was arcing to get notice. It should not be so, if the loose
solder terminals were at the solder points of chroma IC or elsewhere. Will be very difficult to locate. The easiest way is to de-solder out solder from all the
suspected solder terminals, and re-solder by applying fresh solder, without
making any solder bridge short in between adjacent solder terminals.
CLICK ON THE PICTURES TO MAGNIFY
