I have a Westinghouse LCD 20 TV. (LTV-20V4). I was watching the TVsuddenly the TV picture goes away and the LCD became completely blackbut I Had sound. Then I turned the TV off and on couple of times the Ihad sound, but no pictures again. I turned the TV on and off again andthe sound didn't come anymore. (At this moment no pictures and nosound). Now when I turn it on it shut it self immediately. I'm in acountry which there is no delegation of Westinghouse I would really appreciated if you could help me and tell what is the problem with the TV! email me at [email protected]
Thank you
I had this problem with these tv`s. As mentioned the problem lies with the
power supply inside the unit. Some of the units i`ve seen have 2 blown
capacitors on the power supply (C7 and C6 which are 0.227microFarad) replacing these works. On
others, the capacitors as well as a few transistors
(Q8 - Q1, HSD965) are
blown. But on all the sets i have seen with this problem, changing the
above components restores full functionality to the system.
This problem is with fair certainty the
power supply.
Modern power supplies are designed to shut down if
the current drawn exceeds the design level which indicates that something the
supply services or the supply itself has died.
If you are adventurous, you might pull the plug on the set, allow
the set to sit overnight, gain access to the innards, and with good light,
inspect any boards inside. If you see one that has few ICs but many more larger
discrete parts, this will be the power supply.
You are looking for components called electrolytic
capacitors that are almost always cylindrical and mostly installed upright at
90 degrees to the board with leads passing through to the solder side.
This same type of component in smaller dimensions
is still used in a horizontal package with leads bent down and passing though
holes to the solder side.
The latter are becoming more rare since they don't
lend themselves well to robot assembly.
Many (not all) will show signs of pregnancy when
they fail, bulging unnaturally when compared with others. Now and then, there
may be traces of a crystalline deposit around the end where the seal failed
from internal pressure.
These will have values listed on them in uFd & VDC
and sometimes, a plus/minus number lying about the precision.
Some also have a date code (rarer) that will look
like four digits:
2403 = 24th week of 2003
Most electronics suppliers have a stock of
the various values but if they have a date code at all, try to get only those
made before 2002 or after 2006.
The larger caps will probably be OK since the failure is likely
related to functions other than brute-force filtering. A pretty good 'rule of
thumb' is to replace any caps you see bulging that are 100 uFd or less.
If you choose to replace these yourself, you will need a quality
soldering iron with a small, preferably iron-plated tip, rosin core solder and
a sponge which when wetted is used to frequently wipe oxidized solder from the
tip this should be kept bright and clean and fresh tinning will keep it that
way.
You should also buy some solder 'wick' with the iron; this is used
to place on the solder you wish to remove and then heated with the iron.
Properly used. the wick will absorb nearly all of the solder from the lands
from which you wish to remove a component.
Since many manufacturers purchase the power supplies from specialized companies, the power board is usually a separate assembly and you should be able to recognize its relationship to the AC cord.
The supplies are 'hot' all the time to keep low voltages available otherwise your remote wouldn't be much good for turning the set on, so tracing the power cord coming in should bring you to the power board.
There may be a second board that would be smaller and producing the high voltage for the fluorescent backlight; if this one had failed, you would still have sound.
This board will probably have some connection to the main power board deriving its DC input from it.
The power board may have more than one part number on it; one that is obviously etched along with the printed circuit traces, and a second one, sometimes on a label, that will identify the assembled board. The former is the maker's ID for the bare board.
If you can locate the latter, you might do a thorough search to see if a company offers repair of this board which will be in any case lower than the cost of a new one.
I can't guarantee that the main power board is the only problem but it is very likely since you have lost both video and sound now.
Have to repeat myself here:
"The power board may have more than one part number on it; one that is obviously etched along with the printed circuit traces, and a second one, sometimes on a label, that will identify the assembled board. The former is the maker's ID for the bare board. If you can locate the latter, you might do a thorough search to see if a company offers repair of this board which will be in any case lower than the cost of a new one. "
Until you attempt to locate the part number as described, neither of us can find a replacement or a repair service.
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Thank you, Do you know where I can find the power board? So I have to change the whole power board and everything will be fixed?
Do you know a cheap place that I can buy the power bored from it (online).
Thank you
I think I need a p/s also. Is there a place that carried these?
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