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I have seen many reports of screens going randomly blank but none similar to what I experience.
After having worked perfectly for years on another (Ubuntu) laptop and for days on this laptop, the external monitor (VGA, LG Flatron L1915S) on my laptop now goes blank randomly and stays blank - even though the status LED on the monitor shows it is on.
I would love some help to diagnose and fix this issue.
I can't see any error message in dmesg.
Where the mouse is located in all of this (on which screen) seems to have no impact.
I can easily restore the screen by pressing the on/off button twice, or via software by running the following two commands (just issuing the second command does nothing):
xset dpms force suspend # or standby or off (same result)
xset dpms force on
But then the external monitor goes blank again, sometimes in less than one second, other times after several minutes, rarely more than half an hour. It does not seem related to the screen saver or DPMS, as it sometimes happens (after reboot) long before any DPMS or screen saver timeout is triggered (the laptop screen stays on).
I tried changing the refresh rate from the default 60.02 to the alternative 75.02, and it seemed to do the trick for the rest of one evening (even with a screen saver on), but the next day the blanking problem came back again.
I tried to disable blanking, it did not change anything, the screen still blanks after minutes or seconds
xset s noblank
If I reboot while the external monitor is blank, the reboot unblanks it.
I log in and let it sit for a while having started no application, blanking tends to not happen, though it sometimes does.
Sometimes it seems related to actions (closing a window on that screen, cursor leaving the window), other times it is clearly unrelated as some blanks happen when there is no on going action (mouse & keyboard untouched).
When the external monitor does go to stand-by mode after the relevant timeouts (and the main laptop screen is in stand-by too), shaking the mouse unblanks both monitors, but then the external monitor often blanks shortly afterwards.
Changing the refresh rate while the screen is blank does not unblank the monitor.
xrandr --output VGA-0 --rate 60.02
xrandr --output VGA-0 --rate 75.02
While issuing the command with the --mode switch does unblank the screen (although only momentarilly).
xrandr --output VGA-0 --mode 1280x1024 --rate 60.02
xrandr --output VGA-0 --mode 1280x1024 --rate 75.02
After one of many reboots the external monitor blanked before I could even login. I decided to login blind (with screen blank), when it opened the session, the screen un blanked, but then blanked shortly after again.
Trying to disable DPMS on the external monitor does not solve the problem:
> cat /etc/X11/xorg.conf.d/10-monitor.conf
Section "Monitor"
Identifier "LVDS"
Option "DPMS" "true"
Option "Primary" "true"
EndSection
Section "Monitor"
Identifier "VGA-0"
Option "DPMS" "false"
Option "RightOf" "LVDS"
EndSection
Section "ServerLayout"
Identifier "ServerLayout0"
Option "StandbyTime" "0"
Option "SuspendTime" "0"
Option "OffTime" "0"
Option "BlankTime" "0"
EndSection
> reboot
Some system information:
the laptop is an ASUS Pentium 4 with 1GB RAM, other than that recent screen blanking issue with the external monitor, everything works fine (a bit slow but fine).
I run lxde/lxdm with xscreensaver
> uname -a
Linux asm 4.5.4-1-ARCH #1 SMP PREEMPT Wed May 11 22:42:28 CEST 2016 i686 GNU/Linux
> lspci -v # video card:
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] RV200/M7 [Mobility Radeon 7500] (prog-if 00 [VGA controller])
Subsystem: ASUSTeK Computer Inc. Mobility Radeon M7 (L3C/S)
Flags: bus master, stepping, 66MHz, medium devsel, latency 64, IRQ 5
Memory at d8000000 (32-bit, prefetchable) [size=128M]
I/O ports at d800 [size=256]
Memory at d7000000 (32-bit, non-prefetchable) [size=64K]
Expansion ROM at d7fe0000 [disabled] [size=128K]
Capabilities: [58] AGP version 2.0
Capabilities: [50] Power Management version 2
Kernel driver in use: radeon
Kernel modules: radeon
> xrandr
Screen 0: minimum 320 x 200, current 2680 x 1050, maximum 4096 x 4096
VGA-0 connected primary 1280x1024+1400+0 (normal left inverted right x axis y axis) 376mm x 301mm
1280x1024 60.02 + 75.02*
1152x864 75.00
1024x768 75.08 75.03 60.00
832x624 74.55
800x600 75.00 60.32
640x480 75.00 60.00
720x400 70.08
LVDS connected 1400x1050+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
1400x1050 60.77*+
1280x1024 59.89
1280x960 59.94
1280x854 59.89
1280x800 59.81
1280x720 59.86
1152x768 59.78
1024x768 59.92
800x600 59.86
848x480 59.66
720x480 59.71
640x480 59.38
S-video disconnected (normal left inverted right x axis y axis)
> xset q
Keyboard Control:
auto repeat: on key click percent: 0 LED mask: 00000000
XKB indicators:
00: Caps Lock: off 01: Num Lock: off 02: Scroll Lock: off
03: Compose: off 04: Kana: off 05: Sleep: off
06: Suspend: off 07: Mute: off 08: Misc: off
09: Mail: off 10: Charging: off 11: Shift Lock: off
12: Group 2: off 13: Mouse Keys: off
auto repeat delay: 500 repeat rate: 33
auto repeating keys: 00ffffffdffffbbf
fadfffefffedffff
9fffffffffffffff
fff7ffffffffffff
bell percent: 50 bell pitch: 400 bell duration: 100
Pointer Control:
acceleration: 20/10 threshold: 10
Screen Saver:
prefer blanking: yes allow exposures: yes
timeout: 0 cycle: 0
Colors:
default colormap: 0x20 BlackPixel: 0x0 WhitePixel: 0xffffff
Font Path:
/usr/share/fonts/misc/,/usr/share/fonts/TTF/,/usr/share/fonts/OTF/,/usr/share/fonts/Type1/,built-ins
DPMS (Energy Star):
Standby: 7200 Suspend: 7200 Off: 14400
DPMS is Enabled
Monitor is On
Last edited by asoundmove (2016-06-14 07:42:28)
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That is an LCD display. You also say that it is years old; perhaps old enough to use CCFLs (Cold Cathode Florescent Lamp) in the backlight?
If so, perhaps your inverter that generates the high voltage strike voltage is failing.
Try this, when it goes dark, reduce the ambient light as much as possible. Using a flashlight (torch), illuminate the screen by holding the light off to the side of the screen and point it so that it illuminates the display at a low angle. Then, looking at the display from various angles, see if you can see a picture on the display. If so, it might be an indication that the computer is working fine, but that the monitor is the problem. If it is, it is likely a breakdown in the secondary winding of transformer on your inverter.
This can be fixed. http://www.lcdparts.net/u3d.aspx
But be careful -- If you touch the inverter or its output leads while it is running, you may be doing the high voltage dance.
Last edited by ewaller (2016-06-13 14:46:34)
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Wow, you are right - I really did not think it was a hardware problem.
The low angle flashlight approach did not work for me, I could only see the screen's surface.
Instead I shone a smartphone's LED flashlight right into the screen very close-up, that revealed the image in the screen.
So off to do some DIY (unpowered off course) to check what I need.
Thank you.
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Please mark this as [Solved] not as [Closed]. Solved means you found a solution to your problem, closed usually means the thread derailed without reaching a solution/conclusion.
R00KIE
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That is an LCD display. You also say that it is years old; perhaps old enough to use CCFLs (Cold Cathode Florescent Lamp) in the backlight? ....
ewaller, you never cease to amaze me.
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