REPAIRING AND NOT THROWING AWAY

REPAIRING AND NOT THROWING AWAY

Richtige Fernseher haben Röhren!

Richtige Fernseher haben Röhren!

In Brief: On this site you will find pictures and technical information about Service Modes, Circuit Diagrams, Firmware Update procedure, Disassemble procedure, Universal remote control set-up codes, Troubleshooting and more....

If you go into the profession, you will obtain or have access to a variety of tech tips databases HERE IT IS Master Electronics Repair !.

These are an excellent investment where the saying: 'time-is-money' rules. However, to learn, you need to develop a general troubleshooting approach - a logical, methodical, method of narrowing down the problem. A tech tip database might suggest: 'Replace C536' for a particular symptom. This is good advice for a specific problem on one model. However, what you really want to understand is why C536 was the cause and how to pinpoint the culprit in general even if you don't have a service manual or schematic and your tech tip database doesn't have an entry for your sick TV or VCR.

While schematics are nice, you won't always have them or be able to justify the purchase for a one-of repair. Therefore, in many cases, some reverse engineering will be necessary. The time will be well spent since even if you don't see another instance of the same model in your entire lifetime, you will have learned something in the process that can be applied to other equipment problems.
As always, when you get stuck, checking out a tech-tips database may quickly identify your problem and solution.In that case, you can greatly simplify your troubleshooting or at least confirm a diagnosis before ordering parts.

Happy repairing!
Today, the West is headed for the abyss. For the ultimate fate of our disposable society is for that society itself to be disposed of. And this will happen sooner, rather than later.

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..............The bitterness of poor quality is remembered long after the sweetness of todays funny gadgets low price has faded from memory........ . . . . . .....
Don't forget the past, the end of the world is upon us! Pretty soon it will all turn to dust!

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All posts are presented here for informative, historical and educative purposes as applicable within fair use. NOTHING HERE IS FOR SALE !

Tuesday, 26 February 2019

HOW TO REPLACE BACKLIGHT INVERTER BOARD TO LCD TVs

HOW TO REPLACE BACKLIGHT INVERTER BOARD TO LCD TVs


Backlight inverter is a power supply that rises from a small DC voltage up to a few hunderd volts, used to feed the CCFL backlights.  Eventhough the voltage is high, the current will be very low.  Typically 6 to 7 milliamps. 

FAULTS WITH BACKLIGHT INVERTERS.
  1. No display.  Power indicator light at the front panel of the TV will stay on green or blue.
  2. Screen might flash On and Off, and the power indicator light will stay on green or blue.
  3. There will be no picture on the screen, but Tv will have sound output.
  4. The screen will flash On and Off, and the tv will have sound.
  5. Light intensity to screen is low [Dim display]/
There are universal inverter boards can be used on many kinds of LCD screens.  The compact size of these boards allow you to mount it anywhere near the LCD screen.
To find the exact replacement of universal inverter boards, you have to know about the number of CCFL lamps fitted with your LCD screen, and the input voltage applied to inverter board.
No technical skill need, and anyone can replace these board.  Must have patience and concentration.

MEASURING THE INPUT VOLTAGE APPLIED TO INVERTER BOARDS.

All invertes will have an input filter capacitor. The positive pin to this capacitor will be connected to positve supply rail, and the negative pin to ground [chasis].  you have to measure the voltage between these two pins of capacitor.  It will be the input voltage to inverter. 
Locate this capacitor. a photo of it has been included here.  The position to it may differ to board to board.


See, this is a universal backlight inverter board for a single CCFl lamp.  You can see , one inverter transformer.  See the large black electrolytic capacitor.  The voltage acorss it should be measured, and it will be the input voltage to the inverter.  From the number of inverter transformers fitted, you can understand the number of  CCFL backlight tubes inside the panel.  If there is 10 of them, there will be 10 inverter transformers be there on board, and vice versa.

In some cases, there will be one inverter transformer drive two CCFLs.  In such cases, the number of inverter transformers will be 1/2 number of CCFLs inside the panel.  See here an inverter baord shown above is for 12 CCFL lamps, but have ony 6 inverter transformers.  So, it will be best to make sure about thenumber of CCFLs in your LCD panel, by refering the service manual to that particular set.  CCFL stands for [Cold Cathode Flourocent Lamp].

Set your multimeter to read DC voltage range.  Use of a digital multimenter [auto ranging type] is recomended.

Turn OFF the device
Connect the Black probe of the multimeter on power ground.
Connect the Red  probe to positive pin of the capacitor.
Turn ON the LCD TV.  The applied voltage can be measured by the multimeter.
If no voltage found, check the supply path.  The power supply to backlight inverter comes from the main power regulator section of the TV.  If there is no voltage measured, power supply regualtor board also should be checked. 

It is best to check the CCFL lamps inside the panel too before replacing the inverter board.  If there is any CCFLs have burned ends [black band on end], replace them too.  Like oridinary flourcent lamps, these lamps too have a pre-determined life span.
Posted By: FRANK at 04:30
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