Forum Thread

Checking the inverter board and CCFL lamp for a HP ProBook 4530s Notebook PC running Windows 7 Professional

p_s_92 564 52 July 15, 2013 at 06:06 AM
Some days when the laptop is turned on, the user sees only a blank screen. But, the notebook starts up fine as connecting it to an
external monitor shows the different accounts on the notebook. The user can log-in to the account and use it. Other days, the
notebook monitor works properly and everything shows up properly and user can use it without issues. I estimate something is malfunctioning with the inverter board for the LCD or the CCFL lamp on some days. There was no diagnostic tools which came with the laptop
to check those parts.

1. How can I check if the inverter board for the LCD or the CCFL lamp are working fine or not?

2. Is there a software utility I can use to check them(inverter board or CCFL lamp) before I open the LCD?

3. Can something else be causing the issue?

I notice http://www.laptoprepair101.com/la...ccfl-lamp/ and
http://www.ccfldirect.com/lcdtutorial.html explain how to replace the lamp. However, I want to find out which
is faulty(lamp or the inverter board)

The laptop was purchased in Oct 2011.

Any suggestions would be appreciated.

Thanks

16 Comments

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#2
well neither is faulty since they sometimes work I would look at a bad wire by hinge or a sticky switch that turns the display off when closed have you removed the screen from the laptop and tried to make it go black? I am not sure how the switch works
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#3
The only thing I can say is that you don't know yet if it's just a loose connection or a defective LED backlight and the only way you will find out is by opening it and playing around with the connections and wires.
It is impossible to make the correct decision about what to do, until you have opened it up and determined the solution, which is either to make a better connection or replace that inverter.

PS: I should mention that if it is in fact a backlight issue, you should be able to see what is on the screen by shining a flashlight on it.
If you see nothing, then it wouldn't be the inverter, but still could be a wire or connector.
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Last edited by RockySosua July 15, 2013 at 07:20 AM
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#4
Quote from komondor View Post :
well neither is faulty since they sometimes work I would look at a bad wire by hinge or a sticky switch that turns the display off when closed have you removed the screen from the laptop and tried to make it go black? I am not sure how the switch works
Thanks, how do I find the faulty wire by hinge?

I have not removed the screen from the laptop since when I started it was working fine. But, the user sometimes gets a blank screen.
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#5
Quote from RockySosua View Post :
The only thing I can say is that you don't know yet if it's just a loose connection or a defective LED backlight and the only way you will find out is by opening it and playing around with the connections and wires.
It is impossible to make the correct decision about what to do, until you have opened it up and determined the solution, which is either to make a better connection or replace that inverter.

PS: I should mention that if it is in fact a backlight issue, you should be able to see what is on the screen by shining a flashlight on it.
If you see nothing, then it wouldn't be the inverter, but still could be a wire or connector.
Thanks, since the model has a LED backlight, does it have a high voltage inverter?

Are there any signs of inverter failure(like when lamps fail, they flicker for a while, then go out?) I understand for a notebook less than 18 months old, a inverter failure is rare just like a backlight issue.
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#6
Quote from p_s_92 View Post :
Thanks, how do I find the faulty wire by hinge?

I have not removed the screen from the laptop since when I started it was working fine. But, the user sometimes gets a blank screen.
Quote from p_s_92 View Post :
Thanks, since the model has a LED backlight, does it have a high voltage inverter?

Are there any signs of inverter failure(like when lamps fail, they flicker for a while, then go out?) I understand for a notebook less than 18 months old, a inverter failure is rare just like a backlight issue.
You'd have to research the model to know if it is high voltage or not, although I have no idea why that might make any difference, unless you are referring to REAL high voltage, like dangerous for your health, in which case, no, it is not high voltage..
The last person whom I spoke to about replacing one, found it on eBay.
As for how to find out which wire or connector is loose, assuming that is the problem, dismantling the screen will do nothing for you.
You have to take the body of the laptop apart, then poke around the area where the power and data cables are that go to the screen, until you make it flicker.
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#7
Quote from p_s_92 View Post :
Thanks, since the model has a LED backlight, does it have a high voltage inverter?

Are there any signs of inverter failure(like when lamps fail, they flicker for a while, then go out?) I understand for a notebook less than 18 months old, a inverter failure is rare just like a backlight issue.
LED's don't run off high voltage. Most run well below 5V.

I agree with Rocky that it's likely the cable between the laptop and the screen that is bad. This seems to be a common problem on some machines. Personally I have seen it more on HP's than other brands.
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Vague questions receive vague answers . . . . . .
#8
its over heating blow out the dust,the graphics card could be overheating get a program to run fan at full


look up HP ProBook 4530s overheating some say changer ghrapics driver
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Last edited by feeldeal July 16, 2013 at 12:30 PM

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#9
Quote from feeldeal View Post :
its over heating blow out the dust,the graphics card could be overheating get a program to run fan at full
Dude,
You have to stop giving advice about stuff you know nothing about.
It's hard enough to solve tech problems online, without your misleading information.
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#10
CCFLs tend to last longer than inverters, and LEDs last about forever unless the inverter feeds them way too much current. I'd first check for bad connections at the plugs and sockets or for cracked solder there. LEDs can be checked like regular diodes, but a digital meter may not apply enough voltage to turn them on, so you may need to apply a slightly higher voltage (5V) through a current-limiting resistor (resistor is a must to prevent burning out the LED) to see the LED glow. Or maybe use an old-style analog meter set to a higher resistance range that's powered by the meter's 9V battery.

I don't know if the backlight inverter is a separate unit or is built into the main power supply, but you may be able to do a rough check with the power disconnected by measuring individual components, like any fuse, MOSFETs, or diodes, with a meter's ohms or diode check function. Capacitors will often test out OK despite being in bad shape.
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#11
This is a shot in the dark but when it happens next, have the user hold down the fn button and hit F4. I *think* that toggles between the screens. If that restores the display, check the bios to see what the primary monitor is set as and update the video driver.

I know it is a long shot but I have seen stranger things.
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#12
Quote from RockySosua View Post :
You'd have to research the model to know if it is high voltage or not, although I have no idea why that might make any difference, unless you are referring to REAL high voltage, like dangerous for your health, in which case, no, it is not high voltage..
The last person whom I spoke to about replacing one, found it on eBay.
As for how to find out which wire or connector is loose, assuming that is the problem, dismantling the screen will do nothing for you.
You have to take the body of the laptop apart, then poke around the area where the power and data cables are that go to the screen, until you make it flicker.
Thanks, this is helpful.

Quote from LiquidRetro View Post :
LED's don't run off high voltage. Most run well below 5V.

I agree with Rocky that it's likely the cable between the laptop and the screen that is bad. This seems to be a common problem on some machines. Personally I have seen it more on HP's than other brands.
Thanks, but why could the cable be malfunctioning sometimes and working fine at other times. Could it be a loose connection or frayed wire?

The user got the blank monitor sometimes. When I examined it, it was working fine.
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Last edited by p_s_92 July 21, 2013 at 11:54 AM
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#13
Quote from larrymoencurly View Post :
CCFLs tend to last longer than inverters, and LEDs last about forever unless the inverter feeds them way too much current. I'd first check for bad connections at the plugs and sockets or for cracked solder there. LEDs can be checked like regular diodes, but a digital meter may not apply enough voltage to turn them on, so you may need to apply a slightly higher voltage (5V) through a current-limiting resistor (resistor is a must to prevent burning out the LED) to see the LED glow. Or maybe use an old-style analog meter set to a higher resistance range that's powered by the meter's 9V battery.
Thanks a lot. I will have to find a old analog inverter to test it,

Quote from larrymoencurly View Post :
I don't know if the backlight inverter is a separate unit or is built into the main power supply, but you may be able to do a rough check with the power disconnected by measuring individual components, like any fuse, MOSFETs, or diodes, with a meter's ohms or diode check function. Capacitors will often test out OK despite being in bad shape.
Do LEDs have an inverter or another power circuit? From http://lcd-screen.com.ua/data/pdf/1168.pdf I think the panel electronics runs at 3.3V and LED supply is 6 to 20V.

Quote from marg_fan View Post :
This is a shot in the dark but when it happens next, have the user hold down the fn button and hit F4. I *think* that toggles between the screens. If that restores the display, check the bios to see what the primary monitor is set as and update the video driver.

I know it is a long shot but I have seen stranger things.
Thanks, I will advise the user. The user faced the issue of blank monitor some times. He brought it to me and the monitor worked fine. I returned it and told him to bring it back if it blanks out.
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Last edited by p_s_92 July 21, 2013 at 12:07 PM
#14
Quote from p_s_92 View Post :


Thanks, but why could the cable be malfunctioning sometimes and working fine at other times. Could it be a loose connection or frayed wire?

The user got the blank monitor sometimes. When I examined it, it was working fine.
The connections can be loose as the cables/wires are under stress from each time that the lid is opened or closed, but it could be the cable itself, if there is a miniscule internal break, that will allow the signal to go through sometimes, and other times, not.
If you work in a repair shop and you're handed a laptop with this problem, within a minute, you'd start to take it apart, as it is the only way to get at the issue and once you're in, you poke around to find out if it's the wire, connection, inverter, or whatever.
This particular issue is not uncommon and it's actually a very simple problem to fix.
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#15
Quote from p_s_92 View Post :
Do LEDs have an inverter or another power circuit? From http://lcd-screen.com.ua/data/pdf/1168.pdf I think the panel electronics runs at 3.3V and LED supply is 6 to 20V.
LEDs are usually fed from an inverter, but it's a bit different because it regulates current rather than voltage. That may mean to check it you'll have to place it under load, and the voltage will vary.

You can test LEDs with a digital meter by using a DC source of at least 6V per LED (9V battery works fine) and placing a resistor in series with the LED. The resistor should probably allow 5mA - 10mA flow, so for a 9V battery that will be roughly 1,000 ohms. Remember to use the resistor because connecting the voltage source directly to an LED will burn it out immediately.
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