11

The screen flashes/blanks randomly, when It flashes, It goes blank and stays in blank for like 2 seconds and screen comes back again. But again after having 1 second of screen, it goes blank again. Sometimes it might take up to 10 minutes for it to go blank, but sometimes every 2 seconds it goes blank. I've tested using a 1280x768 monitor and it worked fine without even one blanking. I'm using a HDMI to VGA converter. My own monitor is 1048x768 LG Flatron old monitor. Could that be my monitor is taking some power from raspberry? But if it's taking power, then why does the monitor go blank randomly and why sometimes it works for 10 minutes without blanking?

Also as a note, I've tried hdmi-safe and it was the same. I tried changing the resolution but it was still the same problem.

  • On a side note: are you sure that it is the Pi? I mean do the displays work fine with other sources (e.g. PC, Laptop)? I just happen to have a monitor around that shows such sympthoms without the Pi... – Ghanima Mar 30 '15 at 13:40
  • @Ghanima The monitor works fine with my PC, I've also had some tests with it on a Laptop and It worked fine. The thing is, Monitor's cable input is VGA and the other side of cable where goes to the monitor is something other than VGA, I don't know what It's named. – 111WARLOCK111 Mar 30 '15 at 13:58
  • I'm no expert but I believe the more connectors involved the greater the signal loss. Do you have a normal HDMI TV or monitor you can connect the pi to for a while to compare? – goldilocks Mar 30 '15 at 14:25
  • Have you supplied power for your HDMI convertor? The D to A convertor needs it, and the HDMI cable (pin 18) is only good for 50 milliamps: en.wikipedia.org/wiki/HDMI Your convertor may be intermittently starved for juice. – Wayfaring Stranger Apr 13 '15 at 1:05
  • I had the same problem with the rpi 2 using a powered usb hub. Setting Boost to 4 did not work. I am using an elo touchscreen with vga to hdmi adapter. Will try boost to 6 and changing hdmi group. – Nitin Jul 27 '17 at 14:41
6

I'm not sure this will help, but had this similar problem on my Raspberry (old 1 Model B) also yesterday. I had not noticed it before because I only recently started using it with X and a monitor. Every time I scrolled in a browser window or even an lxterminal the screen would go blank for 2 seconds seemingly randomly. Changing resolution or tweaking with hdmi settings in /boot/config.txt had no effect whatsoever. It turned out that the problem was related to insufficient power fed to the display adaptor. I had my raspberry connected to my router's usb slot and obviously this port is only meant for usb sticks that require far less power, perhaps just a few hundred mAs. Connecting the raspberry to a usb port on my pc solved the problem. No more flashing. So try connecting your unit to a different power supply (one rated for at least 1A, preferably more). I hope this helps anyone with similar issues.

4

In /boot/config.txt, uncomment the line with config_hdmi_boost and change its value to =6.

The suggested value of 4 was still too low for a Samsung 205BW monitor connected to a Raspberry Pi 3.

  • 1
    Beware that it is possible to effectively set that beyond the officially documented maximum of 7, and you may find other people online recommending that. However, we've had someone report here having to increase the number occasionally over time (I think the real max is 11), and eventually the jack stopped working completely. – goldilocks Oct 21 '16 at 18:50
2

I finally solved this issue by changing /boot/config.txt. By setting hdmi_group=1 and hdmi_mode=25, which will set the refresh rate to 100Hz.

  • note specific mode numbers are for specific monitor resolution, so not a lot of good as a general answer. – agentp Jun 19 '17 at 23:48
1

I had the same screen flashing problem. I tried various suggestions here but it did not help. I replaced my 15' HDMI cable with a 2' cable and the problem went away.

  • thank you it was also my problem. – elviejo79 Jun 15 at 21:24
0

I got the same problem of intermittent blank screen on Raspberry Pi 3. Searched the web for many days, didn't find the right answer. It's not caused by a power voltage issue, or HDMI boost parameter as many answers suggest.

I finally solved this issue by changing /boot/config.txt, by setting hdmi_group=1. And hdmi_mode=41. Which will set the refresh rate to 100.

Seems the default configuration doesn't work properly.

0

Here are the modes and other settings needed to understand what is being changed:

https://elinux.org/RPiconfig#Video_mode_options

  • 1
    Kindly summarise the info on the link in case it changes. :) – tlhIngan Nov 8 '17 at 5:53
0

The simplest answer I've personally discovered is that an aux cable or even a dummy 3.5mm jack needs to be plugged into the HDMI to VGA adapter always , if not the pi finds audio not being picked up I guess and it tries to identify the display causing the screen flickering cz HDMI has both audio and video . When the 3.5mm slot in the adaptor is plugged with anything, screen flickering stops

0

Add this line to /boot/config.txt

disable_splash=1

Then reboot 2 times.

0

This problem started happening after my RPI Model B+ lost power suddenly.

Several reboots and "fixes" to /boot/config.txt (described above) did not help.

What worked for me was to go the drive eject icon in far upper right corner of screen and eject my SD card. After a reboot, problem was fixed.

protected by Darth Vader Jan 28 at 8:35

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