An expert who has achieved level 3 by getting 1000 points
An expert that got 10 achievements.
An expert that got 5 achievements.
An expert who has answered 1,000 questions.
Re: monitor comes on but the screen gets dark after a 3...
If the power indicator at the front panel stay lit but no screen display or black screen, it could be a sign of bad power inverter board or screen back light. now to ensure if it was the cause you can do a voltage checking, at this time you will need a digital tester. you need to know if their is a bl_on voltage at the power inverter board around 3-4.4v to turn on the inverter board that supply the back light.if the power inverter board has 12v dc and has bL_ON voltage then the cause will be a bad inverter board. you must check also for a dry joint connector going to back light.
- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
Back - light problem. Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis. http://electronicshelponline.blogspot.com/
To some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement. To some models sets, the back-light inverter and SMPS section circuit will be integrated at its main board itself. If so; the main board should be replaced. To some models of sets, all these section circuit will be integrated at its main board. If this is the case, you have to replace the main board.
You need to give a more detailed description of the problem. The LG 47LH90 is an LED backlit TV with 'local dimming' technology. This means that there are lots of white LEDs behind the screen and these can be controlled in groups to allow localised areas of the screen to be dimmed to produce better contrast between light and dark. It is very likely that when the room is dark, this local dimming is more noticeable. The actual individual LEDs cannot be controlled and so the area that is dimmed will generally be greater than the area that is required to be dark 'blooming effect'. In addition, LED backlit displays only maintain their contrast through a tight viewing angle. If you sit too farto the right or left, then light from non-dimmed LEDs will leak through and the screen will look lighter. In short, there may not be any fault with your TV.
I would say you either have a damaged inverter board or screen baclight lamp. Usually the inverter board fails in one of the following ways:
1. When you turn on the laptop, the screen lights up for a short period of time and then goes dark. You still can see an image but it is very dark, almost invisible and definitely not usable. When you restart the laptop, the screen lights up and then goes dark again. The laptop works fine with an external monitor. 2. Your laptop turns on but the screen remains dark all the time. You still can see a very dim image outline. The laptop works fine with an external monitor. 3. The laptop screen works fine for hours or even days, but sometimes it goes very dark as it mentioned above. When you restart the laptop, the screen works fine again.
Inverter failure symptoms are very similar to backlight lamp failure symptoms and in most cases you cannot tell which one is causing the problem until you replace either the inverter board or the backlight lamp. From my personal experience, inverter boards fail more often than backlight lamps. If you have to guess, replace the inverter first.
The fault could be a faulty inverter or a faulty CCFL lamp. The inverter supplies high voltage to the CCFL lamp, if faulty the CCFL lamp can flicker or not light up. The CCFL lamp is a mini fluro lamp, and flicks on and off when faulty especially as it ages. Check out LCD Parts for service, parts, and DIY info Use this link to their WEB site :- www.lcdparts.net
You may have a faulty inverter or a faulty CCFL lamp.
A defective CCFL backlight, it may have the following symptom: Screen flashs on red/pink and off. Picture stays on in red and slowly be come normal. Picture flickering with dim display or appear black. Picture flickering on and off. All these symptoms indicate that the LCD backlight lamp (CCFL Lamp) has reached the end of the life and all you need to do is replacing the CCFL lamp. Connect an external monitor to your laptop and power the monitor up first then the laptop, if you see the normal Windows images then the video card and laptop is OK and the problem is definitely the backlight. Dim image and/or dark display on the laptop's LCD screen indicates a faulty LCD backlight and it could be the inverter that supplies high voltage to the CCFL lamp or it is the CCLF lamp is nearly burnt out or burnt out, most likely this is the case. The inverter can be replaced easily but the CCLF lamp is more time consuming and requires soldering skills. Check out www.lcdparts.net
You just bought a new power supply for the monitor? Did you set the B+ voltage to the correct settings. Rebuilt power supplies for CRT monitors are not set correctly at the factory. Use your schematic to determine the proper B+ and then set this under load.