Desktop Display Monitor tests and diagnosis          

VGA/HDMI/DVI/DP external monitor displays.
(test it on desktops or on Laptops with VGA jacks, or HDMI to a TV) Fast checks here?
You are here because (vast reasons) the screen is dead, or shows errors , the OSD menus are dead or locked, the screen pixels many are dead( a few are normal) funny  lines on the screen, stuck in sleep mode, or sleep mode wanted is dead, or some  person turned on the 2006 or older internal monitor sleep timer, so turn it off in the OSD menu's
The screen can be cracked (no need to tell you that is the end)
If the screen is dead on 2 PCs or more then the screen is bad, and needs service or has  bad CCLF lamps.
Kinda related to this is if you upgraded to a power hog GPU the screen goes dead. (PSU overloaded and monitor tests ok on 2nd PC)

Skipping past Cathode ray tubes all displays now are LCD flat screens (most are, I am skipping OELD and Plasma screens too)

Monitors have  many types of  failure modes,  including failure to sleep, caused by bad cables, bad  drivers in PC or using new PC on monitor older than 2007 (eDID began then)
Plug and play eDID,can fail for these reasons.
The video cables or power cable to the monitor loose or fell off, or tripped on and now broken or pins smashed, end to end.
Most monitors  have 1 or 2 LEDs or just the one inside the Power button on said monitor.
Many monitors have yellow(amber) or GREEN STATUS LED here.
The amber glowing can mean the monitor is sleeping, if flashing it can mean , all inputs channels are dead. (only your monitors users manual covers the truth here)

Or the act of unplugging  all these   VGA/DVI,HDMI, DP, cables will cause  all monitors to go to sleep, even tells you that. (my View sonic, DVI shows, "NO SIGNAL" doing that, clear as day.)
The older monitors (2000 to 2010?) sure can go to self induced sleep (OSD TIMER), and tells you that if you watch the screen so turn that off that first.
One guy has  monitor with an AC/DC power LINE pack and was the wrong pack plugged in. oops.
Does the Monitor fail on 2 PC's for sure one known to be good PC? yes/no;  if yes, try a new VGA cable, still bad this is a bad monitor. (I can assume you  know where brightness knobs or OSD setting are?)
This monitor can fail just like laptops do to cracked screens or CCLF going bad or the inverter on the  main power board failing as seen here. (the data board inside can do dead too)

Next is Power on Tests.
  • I push the power button and you will get a makers LOGO  and the Energy star logo, or both like this.
  • This pop up logo will last for 10-30 seconds and then shows "going to sleep" (PC missing or off or in sleep mode)  If this logo and message above is missing or looks ugly the monitor is toast (bad)
  • If  good PC is running connected up the OSD menu, if the botton works ok on the front of the monitor. Like seen below.? That is good sign of good, do more testing.
  • The error messages can show many error missages , Like No signal. (and if true the PC video cable is dead, only why remains)
  • You can power on 10 times and see the same clear logo, even if the no PC present. (if not? that is a bad monitor)
  • The OSD menu and deep settings inside may not be accessible until the PC is working and connected. (this is to prevent screen damage)
  • The processor brain inside the monitor, wants to see good and legal sync signals before going to full operation, with full video presentation.
The Power button light (LED) on some have 2 or 3 colors. (HP has this)
Amber, = sleep mode. (usually only after 10 seconds see this or PC goes to sleep mode or hibernate mode)
White/blue/green = all mean power ok.
Black + power light dead, means monitor is off or dead monitor or its power supply is dead ,inside or the outside power pack DC/AC. (not really a color black, but you know what I mean.
The Desktop external monitor powers on and will always show a logo "HP" ,  or some makers logo then "Energy Star (very common in USA) then shows errors. My desktop LCK shows "Viewsonic"
  • "NO SYNC" errors.  means the horz/vertical sync lines in the cable are dead. (PC issues)
  • "NO signal" means  1or both Video lines in cable are dead. (PC issues)
  • "No connection" errors means all lines are dead, in the cable. (PC video dead)
  • OUT OF RANGE (means you connected  new PC to a relic monitor, and the resolution is set to and illegal RANGE. (TRY 800X600 resolution and work up from there or read the screens spec)
  • Screen OSD locked, push the menu button for 10 seconds, now it unlocks.
  • Old monitors had internal sleep timer or sleep clock,  best is to hit the  OSD menu button  and turn OFF POWER_SAFER mode or timer. (Sleep timer off)
  • Screen scans below failed? Mine show live,  VGA/DVI/HDMI,DP  port scans , if all 4 are dead, it tells you that and goes to sleep. (in 10 to 60 seconds, (varies by makers model, mine is adjustable to 60)
You turn on the monitor and then promptly goes black?  If true the PC is dead, or is locked in sleep mode, or the VGA/DVI/etc cable is bad , missing .
 (if 2 monitors fail on one PC the PC has issues, or later or see this (or the reverse monitor fails on all PCs)
This will be normal actions with a dead PC, but in all cases the monitor will show, no signal if the PC is fully on first, and the monitor last. (the monitor tells you, and error, NO SIGNAL,etc)
The cable has 5 key/ pins and wires,  Horz. / vertical sync and RGB if any line is dead the monitor will tell you or if just the 2 sync pins fail, if both sync pins fail, the monitor goes to sleep mode.
The OSD menu  button goes dead with NO SYNC. and is normal  (this may be to protect the screen for static burn in  damage if the OSD was left glowing endlessly, with a dead PC and the below menu's glowing for ever..)

(The On Screen Display) OSD,  
What happens as the Monitor is turned on?
Well it too has a brain inide and it does self checks inside then puts up a makers logo icon (Dell , HP or Viewsonic) then scans up to 1 to 5 video input ports for live video inputs that are valid.
If it sees 2 inputs live, one is predomenent. (only your manual tells you this sceret order)
If the silly PC failed to read the eDID data , it might pick and illegal screen resolution, and will be odd locking or the monitor shows "OUT OF RANGE" (means Illegal too high resolution used)
Learn that modern monitors and same desktops can in fact change brightness on the Windows side and does to by the PC talking to the eDID chip, and can be over-ridden in the menu below.

Normally the  monitor will show the PC data presentations of the booting OS or will show an  error. (  if no monitor errors POP next is PC POST errors if any and last Windows errors if any.... the boot process...)
If the PC is dead, (shows NO  sync the monitor can turn off)  Monitors  have at least 2 levels of power, ON, sleep mode or off) seen here.
The OSD menu key on the monitor face bezel  always works if the PC is working right.
If the PC is dead (truly) or only lost video, the OSD runs and works about 10 seconds long, (up to 1min) and is to prevent LCD burn damage with a static, OSD menu forever.  On some new monitors the OSD floats around the screen.
Each monitor has its own rules, some will not allow OSD button to work until the PC video starts working.
I can not show all (VAST)  monitor screens here, but OSD screens are mostly boring and simple and near the same.
The only trick is some monitors flat refuse to OSD present if he PC is dead. Some do , Some do not. (but if the PC is dead, all monitors tell you that, "NO SIGNAL on all cables"
My Viewsonic the OSD manu, and key marked the same,  is dead if the DVI cable is unplugged, but if I turn the monitor on, I get the LOGO and then NO signal , then a black screen. (this is all normal)
I am pressing the monitor bezel Menu button key, now:
OSD 1, On screen Display. PC is working 100% here.

 No signal means the PC is not sending signals to the monitor , then goes to black screen.

A short history of Monitors is simple, 1987(PS/2)  CRT's then 2000 year LCD +CCFL then LCD +LED (2010 year) and last OLED panels), 
Time lines:
LCD+LED , started on the wide screens year 2010. (it took industry 7 years to start using CREE bright white, LEDs,  super expensive)
CRTs ended when LCD hit the shelfs , in year 2003.( they CRTs out sold  LCD for about 7  years due mostly from very high bright white LED prices $1 each, wow.)
The CCLF' short life tubes ending about year 2010.  So there are 7 years of these lame old CCLF monitors(and laptops) still being used, that all turn yellow then die.
How to avoid buying junk PCs and monitors with CCFL (easy buy 2010 or newer) The HP history is here (partial)

Links to read as appropriate to your technology: (years )

Top fails: (first are old screens, with CCLF)
The dead CCFL makes the Screen black and OSD dead.
The CCFL can be  dead, dim, yellow for pure white , intermittant or strobing effects (disco like) Best is to retire this junk the costs of parts and labor are 2 to 10 times what the monitor is worth.
A new screen is like $100 and used good monitor is $40 add labor and you go broke.

Monitors stand alone tests, with no  PC connected, no VGA, no DVI no HTML cables attached, example HP LE2002x .
You power on the monitor and it  shows, this or the monitor is dead.  The red words below show scanning port that shows no signal. All 100 % normal. for 2 dead or missing cables (this photo is missing cables x2)
HP OSD MAIN menu, what you see after pushing the menu button.

If the PC runs you can get there via OSD menu button and crank up the brightness, some displays have dedicated buttons for just that.
Some displays have  built in test pattern , nice to see if the colors are looking ok.
Old monitors have this old school malarkey, timers and what not. Turn it off and then only use the PC side for sleep mode. (if at all) Not Energy Star but Energy-DERP.
WARNING if you do the factory reset seen in main above, all this timer junk goes active, again.(pain)

The below should clear, that you need to turn off the stinking rotten SLEEP timer here this be first to check. 2001 to 2010 super common to see this.
I am pressing the monitor bezel Menu button key, now: This is calld OSD< for on screen display. (the monitors brain does this , never the PC)

If the menu button goes dead, hold menu buttion for 10 seconds and it unlocks.
On more legacy oddity is windows screen saver and you sure can turn that on, and even pick black screens , but ends at a touch of the mouse. (USB ports not in sleep mode sure)

Finding the problem and fix it :  (do not read this , this is only how very old montors work, this is for the rabid curious)
Top failure modes:  (the fast quick tests are here)  this section here is for total screen death , no words , no text no logo's no errors are on the screen ever.
If the monitor is  ok it  shows logos or words  but the PC is dead (you saw "no signal errors" for 3 seconded turned on) then  See black screens here.

Desktop: DT monitors   (when I say VGA port or cable , it means  that or DVI or HDMI what ever you have connected for video to this monitor)
Steps to take for diagnosis:
  1. Plug the monitors power pack in, and turn the monitor , the HP  (or you makers) LOGO must show up and  no signal waring for about 3 seconds or the monitor is bad. (jump to #4 below if this fails)
  2. Connect the monitor under test to a known working PC, turn on the monitor then the PC, the OSD screen can be commanded on with the front panel Monitor menu key.
  3. The display LCD-CCFL is dead , dim, yellow or weak, or its PS_inverter and do the flashlight check
  4. You Error no signal The VGA cable  can be bad, replace it or try a spare barrowed?   (you get this error even with monitor tried on other PCs)
  5. The monitor may also show ("Going to sleep" mode or "power saver mode" in most cause this is the PC messing up.
  6. The older monitors have inside the OSD of the monitor, "Sleep timer, in fact turn off all timers found inside any OSD menu" look carefully some times there are 2 timers or some clock"
  7. The monitor is always best tested on a known working PC of any kind with a VGA jack (15pins) Dshell connector on its rear,  that many have, or if DVI cable /port monitor the same. (or HDMI if fitted)
  8. If the monitor has HDMI port you can test this on your TV. (HDMI cable used)
A good monitor will show the makers logo and no signal error each time the monitor is turned on, PC turned off.   If the monitor is dead look here for REFURB  monitors.
The HP logo and errors seen here, (no sig) are from the Desktop monitors internal Brain.  (not the PC)
Please note that monitors have there own brain (see MCU below? yes a brain processor crude) this brain will show thee status of the main video ports.
RGB = red green blue video, H = horiz. sync, V= Vertical Sync.. this old dog below uses CCLF back lamps.(600volts too or more)

Here is a list of symptoms. and tests and cures if possible.
  • Monitor Power lamp dead,  if amber that is sleep mode or bad power supply inside or outside power pack, dead, or you tripped on the AC line cord?
  • No sign on messages or text or logos ever, that is a dead monitor. (RIP) or not really plugged in to power (reseat all connections)
  • Goes to sleep by it's self even with PC not in sleep mode, turn off the sleep timer using the monitors OSD menu button.
  • Lines on the screen see this. (see the twist test there)
  • Dim, or yellow yellow (with say white notepad program runnning) the CCFL background lamps are bad. (or the lamps go dead randomly or blink oddly disco like strobing effect)
  • Shows going to sleep mode, It is (turn it off same way as next line shows)
  • Shows no Signal or no SIG or no SYNC errors the PC is dead or went into hibernate mode, cure, is turn that off in the PC using control  panel, Power OPTIONS below:
  • Shows error OUT OF RANGE means PC RESOLUTION is set too high for this very old monitor, try 800x600 at the PC settings. (always caused by eDID data chip read errors)
  • Monitor turns itself off, make sure the monitor is not set inside for a sleep timer. (see OSD menu and see all timers inside and disable them all, if power goes off, the monitor is  bad.
  • Does the monitor fail on 2 PCs/ if  yes, then the monitor is bad.

Presentation mode at the PC END, is the best testing  mode for any suspected bad monitor.
Turning off sleep can be easy or hard, depends on how your PC was setup new and if PRO grade windows.
There are 2 key  words related here, or 3,  "Presentation mode,  Performance mode, and NO SLEEP modes" Plus Windows 10 custom power settings profile, set it just like you want.

The Windows control panel , under POWER OPTIONS , setup custom power profile, with your  name.
Then set everything there to NEVER.  see first photo below.
or if this fails.
  1. Try power options first. See photo below. this works for me.
  2. Windows Mobility Center but loves to fail on Desktops and all Windows HOME versions (it's DEAD).
  3. Use your your screen saver in a way to prevent sleep. (google this)
  4. Uses powercfg  command line utility turn it off.  See my batch file nosleep.bat,  run it? (edit it to see  it is safe and IS)
  5. In windows PRO, you can use the GPedit  and turn all things there off. (Group policy editor)
  6. The "Don't sleep" program app. works good.
  7. Put the PC in to Kiosk mode.
  8. Run a top bench mark program that runs DISPLAY bench marks, that keeps the GPU super busy, for testing monitors. (I use PASSMARK Performance)
  9. See my Sleep or DIM page
  10. See my new  why does my PC freeze page.

This is where you setup custom Control Panel + POWER OPTIONS  settings.  W10 has 13 bits to flip but just one for turn off display. This is how mine are.  (and screen saver tuned off)

 Not only are these methods very usefull of a Desplay port PROJECTOR of any Kind but super useful to find bad, monitors or sleep modes all set wrong.

Only LAPtops have this 1st photo below, but added here to show that MS has apps do all these settings.
missing on desktops.

On any  desktop click start or gain the run box windows, and type in  "
presentationsettings.exe" and when it pops up click it.
Win 10, 64bit v1903+

XP relic. Amazingly more powerful then . all on one screen.

Dead monitors for dummies
  • Power button dead and for sure, power on Logo of monitor maker does not show up, that is a bad monitor, (or bad power cable, super rare, but if power pack yes or wrong pack used)
  • Monitor fails on 2nd PC, bad monitor
  • 2 Monitors fail in 1 PC,  that is a bad PC. (see why)
  • Monitor turns on but the OSD menus work but are ugly looking , that is a  bad monitor.
  • Monitor told you one of four errors here, that means the PC is sick or cable bad to it. PC sick click see why above. 
  • Monitor keeps going to sleep , turn off sleep timer in OSD screen, (if it has one) and in the PC seen here.

Failure to Sleep: (by commad of PC, called eDID signaling failure) (Applies to Sleep/ Hibernate/ Hybrid modes when I say sleep) Some new monitors have 3 levels deep of sleep, even to say 3 watts power or less.
  • If the drivers for your Video GPU card or onboard GPU chip drivers are wrong or missing or corrupted, sleep will fail.
  • The video card can be just no good, and has bugs not supporting full sleep modes.
  • Or you have SLEEP MODE  turned off in Control Panel (Power settings)
  • The Video Cable is bad, be that VGA/DVI/DP, HDMI ,etc.  Or bought from fleabay dirt cheap and is not eDID certified. (missing 1 of 3 key pins)
  • That Video cable is too long; a cable over 30 meters. (not likely, but must be said) The eDID uses IC comm's, and the signals must be clean. (if the PC has 2 grounds and if different from the monitor ,eDID can fail)
  •  or it missing eDID pins or wiring that allows eDID to function plug and play fails and so will sleep.
  • Using a New PC with a Relic monitor. (or the reverse, OLD PC on a new monitor) both ends must be eDID functional to work right.  (below year 2007, monitors, with newer PC expect trouble.)
  • If some old CRT monitor sure it fails. Most old pre-2010 year, LCD monitors are dead now, due to dead CCFL background lamps.
  • HDMI can fail if the 2 sync pins fail. Or uses CEC controls(HDMI)
  • If you run modern PC with modern monitors,expect no problems at all with hardware, only drivers fail during OS upgrades are the prime cause.
The eDID tells the PC what the monitor can do then the PC use this logic to control power and sleep.
Learn that many video cards go off line if any of 2 failures happen. This fools some folks in to thinking stuck in sleep mode, and is not anything to do with that.
1: The eDID is dead.
2: Any of the 3 video lines RGB ,  are not drawing current (means line cut) or too much current (CARD DAMAGE protections)

DPMS modes ( wiki)  this magic saved us from adding new pins.VGA and DVI analog modes only. As you can see if either sync line, or cable wires same or pins cut or bent,then the monitor shuts down.
In fact it will tell you going to sleep mode or only cable was unpugged. (and  it for sure does not know why , only that  the 1 or 2 wires went dead. (PC dead or in sleep or bad cable)
I will not ever cover digital modes,  like DP or HDMI, you can learn those by googling or using the wiki first.
Power modes change by the lack of sync, and the may turn off with no sync or just text you to the screen , all input cables dead.
Each connector and its rules of usage are vastly and radically different from old analog video to full blown digital display data methods.
JACKS so many JACKs (connectors all standard)

version 2.  12-9-2017 , 5/7/2019 (sleep mode problems)