The wondrous CCFL flash light trick.           
                           2001 to 2010 PC monitors Cold Cathode Fluorescent lamp tubes ( the bad old days before LED back lamps were used 2011  )  and LAPTOP PC's too.
                           These tubes are the LCD back lamps and  if dead the fully good LCD is now useless.  ( learn to avoid the above stated years of Laptops or monitors)
                           Both pesky laptops and monitors covered here and all tests to discover the true cause failure to the lowest level a PCB/card or module or sub device or component.

Monitors are first,  they just love to fail for dead CCFL back lamp glow tubes and the flash light shows data now, the tubes are DEAD.
The next cause of monitor dead is a DEAD PC
If the monitor works on a 2nd good PC then the monitor is ok and the PC is dead.
The monitor cable must  be good, no bent pins , or dog ate the cable.
The monitors brightness knobs must be turned up full. (knobs or in the OSD menu marked Brightness.)  ( knobs turned or, arrow  up, down or only in the OSD are all the  ways to do brightness)
The monitor turned on last after PC turn on,  2 minutes later or longer, the monitor actually tells you why it fails,  if it shows "NO SIGNAL" then the PC is dead. (no signal proves monitor is not dead, see?)
or the cable is plugged in to the wrong ports at either or both ends. (On some lame monitors with 2 or  more ports, we must  force the correct port in OSD menu's (push the button called menu)
The PC with a GPU card the monitor must only be plugged into the GPU cards ports,  if that fails remove the GPU card and use local PC ports (mobo)
The OSD menu (old relics) have a crude and pesky (odd now, for 1995 PC's) Sleep TIMER CLOCK turn that nasty thing off. now.
All old monitors have a least 3 causes of failure (besides, PC dead, AC power cords not  plugged in to AC power or data/video cable not plugged in correctly to monitor or to the PC's correct video port.
  • CCFL tubes dead. see the flash light test below.
  • PSU (inside Monitor) or its inverter dead, Power supply unit, PCB
  • Logic board (inside monitor)is dead.
  • If the monitors power button LED is 100% dead the PSU board is dead. (and the rare chance the button switch actual is defective (inop)
Any monitor is dead if the OSD pop up menu is dead. (inside the 15second rule or connected to a good  PC)
The test is simple , no PC needs to be used, Power on the Monitor and if the MENU button under 15seconds time, from power on Monitor.
The same hold true the monitor splash screen must work at power on or the monitor is dead (NO PC needed)
I made a simple monitor test flow chart.

Keep in mind monitors are not just for PCs or Desktops but also , NVR, DVR, CCTV security systems, and even for some old TVs due to its dead screen.
A monitor can be used on most Laptop too or if Laptop screen is dead you switch to exernal port, or you just want a bigger screen.
Next up, Laptops

LAPTOPS screen is  dead. (over 20 things inside can fail)
(any Laptop is best tested with no HDD installed, and no old huge battery installed, just run  on AC power pack and the goal is getting BIOS pages to work)1st.

Next is the dead RTC coin cell battery (sorry none last 10+year) <<< or topic is very old PCs. Learn now that if the COIN cell is dead the BIOS goes "CRAZY" and lies to you or goes DEAD screened.
The wrong power pack used,  mixed up with others wrong. (learn to label packs so no mix up happen)
Now the test the power pack for  19vdc or what is stamped on it's side with a voltmeter (DMM)
The PC must turn on and fans must blow, or power is dead. (LED glow correctly too, per your  PC manual)
The PC makers logo splash screen must show up. (or the PC or screen is dead)  (used the flashlight test now.
The BIOS hot key must work, (Dell uses F2 and F12, setup and boot order screen F12 and F12 system diagnostic) If all this is dead do the flash light test next.
Remove the huge battery first.  Do not run old batteries now, or ever, but never us it until the PC works perfectly again.
  1. Power on the PC for 10 full seconds, hold the button for 10 second, and release.
  2. If that fails, remove the AC power pack and huge battery is already remove do these 4 steps.
  3. The laptop turns on and you hear the fan spin (hear ,seen , felt) if yes it may have power rails working.
  4. The next thing that happens is the PC maker splash screen like  my Dell PC LOGO.
  5. The logo on mine has POST progress bar (thank you DELL for that) and must  reach the end.
  6. You can not do, the step 4 due to screen death,  I can not use Dells F12 diagnostic hot key due to screen death. (only your PC makers knows where your diagnotics are located not me.)
  7. I can how ever use the laptops Fn + xyz ( key ) where xyz is the 2 key in your manual, where there is a  ^ Brightness up key , even do so blind. (my dell is Fn+ arrow down) RTM read your manual !
  8. I then do Fn+F4 (this hot key varies by maker RTM) and I do that in BIOS or Windows , either way. this magic key enables the GPU external port, for an added monitor or projector.
  9. If that is dead the external monitor is too, the PC is dead, GPU death is common in year 2007.(GPU/GBA solder ball RHOS lead failure then) Jan 1,2007 and for say 6 months of hell and recalls on that.
  10. You can do 3 tricks here, (tactical tests) we do the flashlight test, then twist the screen bezel  to see screen wake up or see odd graphics and we can twist the PC base too and even push down on the GPU CHIP
  11. If those push or twists cause screen to wake-up, the LCD is bad top twisted or bottom twisted is a bad GPU chip.
  12. The flash light test shows data the CCFL TUBES is dead (or its inverter)
  13. There are other causes, up to 20 shorted parts inside.

Fn+F4  key is not the same on all PCs (this is DELL)  This hot key turns on the external monitor some do this (external, internal, both and auto << 4 choices)  This commonly uses for Protectors. RTM read your  manual
The below is every test I have ever done or seen to find bad CCFL or LCD. 
My dead PC flow chart is here, check it out.

(mine is a small chart, there are some fill up a whole wall in your largest room)
Some PC;s called tablets or pads only have 2 parts,(not counting battery)a PCB main and a screen , like Cell phones <<<not one do I cover. So toss a coin and replace 1 of 2.

Show and tell testing below. (you will learn fast there are vast types of  screen failures and causes) (monitor is bad, or PC bad)

See evidence here, and all tests here.

The screen is 100% black all or most of the time. (The PC fans spin and blow air , all seems ok, but screen is dead.)

"The flash light trick" Desktop or laptops  (just 1 minutes work and bingo ?) In the country UK it is the TORCH test, try not to get burned (LoL)
If the  monitor fails on 2 PC's it is a bad monitor , It is bad CCFL (99%) tubes. (in the year range above only) or just  bad cables.(video cables) or AC  jacks not fully inserted.
Most monitors the sleep mode is indicated at the power lamp LED blinks.RTM your monitor! (so reboot the PC  and that ends on PCs with dead mouse and keyboard)

  1. Turn off the PC then turn on just the monitor next and watch for errors. (and the monitors splash screen)
  2. The monitor tells you "no signal, no sync, no connections or out-of- range"  This tells you now see the monitor is NOT dead, it telling you all that.. (this is a simple monitor test)
  3. Now turn on the PC first , wait for 15+ seconds and then turn on the monitor last.  (turn on windows sounds and turn on startup sounds helps you diagnose this)
  4. If you see same error "no signals" the PC desktop  is dead or the monitor video cable is bad or using the wrong PC video jacks.
  5. If the screen fails all the above, and is always black , then do the flash light test,
You can test the monitor in your  BIOS screens too ( Dell F2 or HP Esc,  hot key'd) or running Windows or any OS of any kind.
I take my flash light, and point (aim) it to my black dead screen face.  (look for DATA  as seen below )
One cute trick in MS Windows is to turn on SYSTEM sounds  in Control Panel "SOUND" so the PC plays that MS startup sound, as it turns on, to you know windows is in fact loading or loaded.
If you know windows is running, you heard it make music, ?
Look at all things on the LCD screen for any thing not black, words text, graphics , or logo's or desktop icons or BIOS screens, or splash screens.
This photo  is of a GOOD PC and  monitor with BAD CCFL tubes, (classic and super  common now)

      Wow the back lamp is dead ! but data and LCD is NOT DEAD !!!

When I see the above, it is best to retire the monitor and if  laptop, the screen  can be $100 parts cost 
One can use a Desktop screen on your laptop   at any time. Your laptop manual shows how to connect a projector using  Fn+F4 or F5 hot key, and this works for any monitor you connected to any laptop.
Some  HP LapTop  have service book telling you the steps to remove this screen and put back the new one. (as do vast PCs in Youtube under "dismantle"
All CCFL devices have a card (PCB card ) that is called and Inverter that is near 600vdc output voltage. If bad sure the tubes fail sure. and is rare for the inverters to fail. (a schematic of one is here)
A typical  inverter card
If any laptop goes dead for CCFL you can run and use a real monitor on it even forever,  sure mobility is lost sure.

Keep in mind that the LCD connectors deep inside might have fallen off  or are loose, for sure if monkeys played inside here before and did not put back the clamping tape to secure it like new.
This is what is dead, just one small example. Those TUBES ARE DEAD.   (some are impossible to reach , in  glued up nasty sandwich.
This is very old monitor 2007 (near)

The above is a very old monitor that the tubes come out  easy (none are kids level easy).  New tubes are sold here.

The CCFL tests are many besides just above , here they are:   Keep in mind OSD is for monitors only or  projectors, not LAPTOPs. (they run only software drivers in the OS to do all this)
  1. The monitor fails on a 2nd or more good PCs.
  2. The Laptop screen fails? We use  a good desktop monitor connected to said Laptop to prove CCFL is dead  behind its LCD screen.
  3. The flash light test fails. (above) (means data good in the beam not not  the whole screen)  if DATA is not there in the beam of light,  the monitor logic board is dead)
  4. The monitors, splash screen (maker logo) no longer shows up  when the monitor is turned on, CCFL is dead. (or inverter rare)
  5. The monitors OSD screen button is dead, (just turned on monitor for under 15 second just it turned on)  this is sign of CCFL death. (monitors go to sleep mode if PC is dead and after 15 seconds monitor turned on)
OSD is On Screen Display (pop up) that is from the monitors brain and shows up if the monitors real menu button is pushed, your manual for your monitor covers this feature. RTM.
Some monitors only can change Brightness settings with a knob (or up/down) buttons on the actual monitor case, others only in the OSD and on some very new monitors the windows driver controls do  this trick.(eDID comms magic)
On laptops there are special keys that set brightness Fn + x (where x is different on all PCs made and models of laptops (RTM) read the manual on yours and go Bingo.

Symptoms of CCFL bad, lots:
  • Dead back lamps CCFL forever no matter what you do.  >>> OSD screen is dead. as is splash screen turned on, even with no PC these both features must work for 15 seconds, as monitor turn on. OR IT IS DEAD
  • Dim black lamps , brightness set to  max.(or 1/2 the screen is dead or dim or acting old in this  list)
  • Yellow tinged.
  • Strobes or blinks, CCFL are no good.
  • It functions ok hot but not cold or the reverse of that. (cold means turned off for  long hours and then turned on cold it runs ok)
Some very old monitors have this crazy sleep timer that must be turned off. Seen here.
A good monitor and good PC that not  sleeping the OSD menu button always works, but   if the PC goes to sleep mode (as all do OOBE) the monitor sleeps too.  (keep that in mind or bark up a wrong tree)

The CCFL can be bad (99% of time is... ) or its inverter card  1% (PCB card) is bad. or worse, the logic board in the monitor is DEAD.
In truth as  with most things are that fail, any of the 4 or 5 PCB boards inside any monitor can be bad, but CCFL tops the list and is the purpose of this page to prove that it is bad.
My page here does not cover this failure, LCD and GPU failures.  BUT TESTS YES below.

This is far far more serious. (LCD bad or GPU bad or just its cable.
The above is for sure a digital failure, not CCFL at all. (the whole screen back lamps work , see ?)
We can do some tricks to here (tactics of a savvy tech)
How to do twists and thumb presses in the rigth places.
We press our  thumb on the rim bezel every few inches to see of lines Happen or go less or even makes more error lines. That is a bad LCD panel (array) LCD can be damaged easy for sure hit.
That trick works on PCs or on monitors. both. (on the rim pressed) I twist the LCD panel at 10AM and 5PM, gently to see if LCD wakes up in any way or gets worse,even like the above photo shows.
Trick #2 is to gently twist the  monitors frame, at say 10AM to 5PM using your hands. If the lines happen or change the LCD panel is no good.
I can twist (a laptop)  base too to see of  GPU wakes up. (GPU is the Graphic chip inside)
Trick#3 is on laptops,  below the keyboard (removed) we press a thumb on the GPU chip (right of CPU is common) if lines happen change the BALL GRID on the GPU is NO GOOD.  Jan1,2007 USA is the day from H3LL.
Trick #4 (a test; a trick; a tactic) is on a monitor to PC, is to wiggle the video cable to see if screen goes wild. Bingo bad connections. there and maybe a new cable. (if not just loose the cable is bad or pins bent)
On Laptops we  re-seat the LCD panels connectors. (yes deep inside)
On Desktop PC we can remove the GPU card and use the local VGA/DP/DVI/HDMI ports to  see if the wild LCD is due to a bad GPU chip or its drivers. (DP and HDMI can do wild things)
On Destop's we can try other GPU cards (vast, even ones for $10 used) (but not on AIO all in one PC's.)
I'd not even bother with fixing any thing this old, as no CCFL device has a future, not at all unless dumping hard $100 cash on it is  fun. (not me! but here is my answer above)

As you learned there are lot of things you can try to learn and do tests to find TRUE CAUSES of any LCD failures. (all it takes are skills, spare parts , lots of time and lots of cash and tools )
Do not touch the CCFL inverter pins or you will get shocked and same is true here. (AC line must be pulled)

version 3.  12-9-2017  (RTM , read the manual on your Monitor first if it fails, or the PC.)