Question about Gateway LCD17TV 17 in. Television
My 26" LCD TV screen is darker/dimmer on left half. The other side is normal. Is it the backlight problem? I tried to locate the lamps/backlights but couldn't find it. The company which made that TV seems disappeared or out of business. Their phone number is disconnected. I have no way to order parts from them. Where can I get backlight for my TV?
SOURCE: Gateway 26" LCD Power Supply
There is a silver lining....
Unless you physically see burned components on the power supply main board, it
is not fried. If you examine the board on the back side ( solder joint side) you will notice that there is a devider that is clearly marked between the Primary and secondary sides of the board. There will also be a large transformer accross this area.
All switch mode power supplies have optical couplers which cosist of a light emmiting diode usually infared and a photo transistor. These are for protecting the secondary side of the board or the expensive side. A typical switchmode power supply for an LCD tv will have at least three of these. They are roughly 1/4 inch long and 2/8 inch wide
and are black with four leads. They will be directly accross the marked portion of the board that seperates the primary or high voltage side of the board from the secondary.
These opticle couplers or switches cost an average of $ 7.00 a piece and are available
from any electronics supplier such as NTE.
I hope this helps. Remember it can all be repaired. Its a matter of if its economically
worth your time.
Posted on Feb 03, 2008
SOURCE: Backlight flashes on and off
When LCD's "turn on" momentarily before going blank again it is an
indication that the backlights have worn out. Cold Cathode Floursecent
Lamps (CCFL's) have a limited amount of hours which they can be in
operation for before the mercury vapor in them breaks down (or leaks
out). When that happens the backlights no longer look like a load the
inverter (device inside the monitor which turns low voltage into high
voltage) is programmed to look for, and long story short, the inverter
does not keep the lamps illuminated because of this being a safety
setting, if the load no longer looks like what the inverter is looking
for, it could be sustaining an open arc which then leads to extremely
high temperatures, and a possible fire. The flash you see is the
"firing voltage" (I think that is what it is referred to in the
industry) which is a very high voltage pulse used to create the arc
between cathodes in the CCFL, creating the arc takes a much higher
voltage than sustaining the arc, so even if the inverter successfully
creates the arc and lights the cathodes, it quickly doesn't look like a
proper load and then inverter quickly turns off to prevent damage. Some inverters try repeatedly so that may be the flashing you see.
In essence CCFL's are usually the weakest link in LCD monitors as far as what is most prone to failure, technology has been improving, but if you keep your monitor on all day long at full brightness, never shutting it down, don't expect more than 3 years out of it :( Some brilliant LCD manufacturers recognize this problem and even make the backlights replaceable!! What a novel concept!!! But due to price gouging, the replacement backlights are usually sold for a premium from resellers, better option than the majority of LCD displays which have the backlights so integrated that you end up destroying the LCD and introducing contaminates in the process of "reviving" the display...
Replacing the cathodes on a 24" display is impractical due to the sheer amount of them, if the panel is not edge lit, there are usually around 16+ cathodes behind the screen, and some are unique to the LCD panel and weird shapes, like U's!
If you still have it, I would definitely be interested in it as parts, but looking at the date of this post I'm sure you trashed it at this point :(
Posted on Jul 25, 2009
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