Re: Hannspree Monitor M19W1 - Pixel Corruption (solved)

[Davespice]

Hi guys;

I was wondering if anyone could suggest anything for me here?

I have pixel corruption on my 1440x900 Hannspree Monitor M19W1
I know the Pi is fine because I have tested it on a 1080p PC Monitor and HDMI TV where it is completly fine.  I have this spare monitor that I would like to use with it though.  However I am seeing this strange kind of pixel corruption which you'll see in the screen shots below.

I am using a HDMI to DVI-D cable for this, the same cable on the 1080p PC monitor works perfectly.  I have also tested the monitor in question on various Windows PCs and it is also working fine there.

I have also tried various options in the config.txt file;

This is what I currently have it set as;

hdmi_drive=1

disable_overscan=1

framebuffer_width=1440

framebuffer_height=900

I have tried it with and without the framebuffer options, no change.

Any help would be really appreciated.  I am thinking it must be something to do with the way the Pi is driving the DVI signal on this resolution.

Open pictures in new window for larger pictures:





Edit: Forgot to mention what distro I am using.  It's debian6-19-04-2012

[frying_fish]

It sounds crazy (I don't have one to test on myself currently), but is the cable fully in. I have seen similar artefacts when I have a digital cable (DVI or HDMI) not 100% inserted into the slot at either end. That might be something to try?

[Davespice]

The cable is fully in yes.  This was the first thing I checked.

Any other ideas?

[dom]

config_hdmi_boost=4 ? (increases signal voltage of hdmi)

[jbeale]

Just out of curiosity, what is the behavior of a HDMI/DVI monitor when you start dropping the nominal 5V power supply in your HDMI source to something lower? Do you loose the signal all at once, or do some pixels in an image drop out gradually?

[Davespice]

dom said:


config_hdmi_boost=4 ? (increases signal voltage of hdmi)


Hi Dom;

This had done the trick!

Do I need to over volt to compensate for this though?

[dom]

No. HDMI voltage is a differential signal not related to any other voltages on board.

I'd be interested to hear whether it works with config_hdmi_boost=1, 2 or 3.

Is the cable long?

Also would be good to know if a different cable allows it to work without config_hdmi_boost (i.e. is the monitor more fussy than most, or is the cable more lossy).

[Davespice]

Hi Dom;

Okay I have done some more tests;

4 = OK

3 = OK

2 = Very few corrupt pixels

1 = More corrupt pixels

I think the blame is with the monitor though.  The same cable on a 1080p PC monitor worked without any issues or needing to use this config option.

I'll link you to the exact cable I am using;

http://www.amazon.co.uk/2m-HDM.....AV2CSY311L

[bredman]

I would like to add this to the troubleshooting wiki, but first I need somebody to confirm some things...

I assume the configuration is in /boot/config.txt

I assume sudo should be used to edit this file.

Is there a chance this file might not exist?

What is the range of allowed values for this parameter? 1-4?

[Davespice]

Hi Bredman

Yes it is the /boot/config.txt file.

Although I was taking the SD card out and editing the file using a Windows PC / Notepad.

I have found the changes do not take when I edit the file on the Pi itself, I think this may be because the /boot folder is mounted read only or something.

The config.txt file will not exist by default and you need to create it.

I have no idea of the allowed range of values, only Dom can answer that one.

[dom]

Some info on config.txt: http://elinux.org/RPi_config.txt

You should be able to edit it on Pi. Make sure you use sudo, and you sync the sdcard before removing power ("sudo reboot" will do).

hdmi_boost=7 is the maximum, but only try that if 4 doesn't help.

[Davespice]

Thanks Dom, I am running with it on 3 and its happy.

Is it;

config_hdmi_boost

or can you also use

hdmi_boost ?

[motty]

Hi Davespice,

I've got exactly the same cable as you from Amazon and I've had the same problem as you with the latest Debian (first Debian image had no problems), although I also get horrible green line flashing around the screen at the initial terminal.

I've tried changing the config_hdmi_boost setting to 4 and it fixes all my problems too. So now I'm a happy person again with my pi!

Rob

[dom]

config_hdmi_boost is the correct name

[modmypi]

FYI I was having a similar problem on my Hannspree TV with the Pi. . . could be something there?

[spurious]

This doesn't look like it's a R-Pi issue

http://www.avforums.com/forums.....ost6209961

[factor6]

I have the very same problem. My monitor is NEC MultiSync 2060NX. I'm using a HDMI2DVI adaptor from DealExtreme. I have set the config_hdmi_boost value to 4. Green dots disappeared, but there are still some in 1600x1200 native mode when running X. The Pi is being powered through USB cable from computer, no external power supply. I think it might be a low power problem.

[johnbeetem]

I get the same behaviour on an NEC LCD19WMGX 1440x900 DVI-D monitor if my RasPi voltage drops too low. Everything works fine with TP1-TP2 = 4.65V, but below that I see the green pixels and/or the monitor blanks out. I suppose I could boost HDMI, but I really need to get my TP1-TP2 up higher by improving my power connections.

My recommendation is to check TP1-TP2, which should be at least 4.8V for reliable operation. See the RasPi Hardware wiki for more info: http://elinux.org/Rpi_Hardware#Power_Supply_Problems

[rcm1985]

Hi Guys,

I am having this same pixel issue on my panasonic led TV (TH L37DT30A).

I have tried both the config_hdmi_boost=4 and =7 and it still hasn't resolved the issue. I have tried different HDMI cables, sd cards and raspberry pi's. I have tried connecting the power from the TV usb and mains power. I have checked the voltage when powering the raspberry pi through mains power and it is 5.10 volts so that appears to be fine.

I can confirm the TV runs my laptop through HDMI fine, and all my other devices running through HDMI (dvd, blu ray player) also work fine. It only appears to be the raspberry pi giving me the pixel issues.

Is there anything else you guys can recommend? I have tried everything so I am open to any ideas.

Thanks for your help.

[dom]

I am having this same pixel issue on my panasonic led TV (TH L37DT30A).

I have tried both the config_hdmi_boost=4 and =7 and it still hasn't resolved the issue. I have tried different HDMI cables, sd cards and raspberry pi's. I have tried connecting the power from the TV usb and mains power. I have checked the voltage when powering the raspberry pi through mains power and it is 5.10 volts so that appears to be fine.

Can you try:
config_hdmi_boost=-7
which I'd expect to not give a picture at all. If it makes no difference, then I suspect something wrong with how you are editing config.txt.
What does

Code: Select all

cat /boot/config.txt

show?

[mahjongg]

Hi Guys,

I am having this same pixel issue on my panasonic led TV (TH L37DT30A).

I have tried both the config_hdmi_boost=4 and =7 and it still hasn't resolved the issue. I have tried different HDMI cables, sd cards and raspberry pi's. I have tried connecting the power from the TV usb and mains power. I have checked the voltage when powering the raspberry pi through mains power and it is 5.10 volts so that appears to be fine.

I can confirm the TV runs my laptop through HDMI fine, and all my other devices running through HDMI (dvd, blu ray player) also work fine. It only appears to be the raspberry pi giving me the pixel issues.

Is there anything else you guys can recommend? I have tried everything so I am open to any ideas.

Thanks for your help.

Did you actually remove the # in front of the line? The line isn't actually activated unless you uncomment it by removing the comment character, just editing the line without removing the comment sign doesn't actually do anything.

[rcm1985]

[/quote]
Can you try:
config_hdmi_boost=-7
which I'd expect to not give a picture at all. If it makes no difference, then I suspect something wrong with how you are editing config.txt.
What does

Code: Select all

cat /boot/config.txt

show?[/quote]

Hi Dom,

Thanks for your reply. I am running the openelec distrobution of xbmc for raspberry pi. By default it has no config.txt file so you have to create one, it is located in /flash, I completed the following steps to create it.

1. mount /flash -o remount,rw (this mounts the flash as writable, by default it is only readable)
2. cd /flash
3. vi config.txt
4. entered the following in config.txt
config_hdmi_boost=4
arm_freq=750
force_turbo=1
5. forced save with wq!
6. i have also cat the file which shows the same input into the config.txt so I know it has saved correctly.
7. I entered the overclock just to ensure the config.txt file is working, I can confirm that the pi is displaying a clock speed of 749.56mhz so its safe to say the file is working.

The dots still appear to show up, I have also set the config_hdmi_boost= -7 and it still displays the same.

I am right in thinking that the command config_hdmi_boost= is not a usable or enabled command in the openelec distrobution for the raspberry pi?

Thanks
Ryan

[rcm1985]

Hi Guys,

Just a follow up to this, I have removed the config_hdmi_boost=4 from the config.txt file and entered hdmi_safe=1 instead. This seems to have resolved the issue with the dots however it is only running in 640x480.

I will continue to play around with the settings in the config.txt file and see if I can find a happy medium.

Thanks
Ryan

[rcm1985]

Ok,

I have setup the config.txt file as follows;

hdmi_force_hotplug=1
config_hdmi_boost=4
hdmi_group=1
hdmi_mode=4 (I have been testing between 4 and 16)
disable_overscan=0

When I run the display in1280x720p (hdmi_mode=4) it is fine and has no issues displaying, as soon as I switch it to 1920x1080p (hdmi_mode=16) the green dots start to appear.

Anyone got any ideas as to why the pi seems to have issues displaying in 1920x1080p, its running the openelec distribution for the raspberry pi. I have checked the power and it is sitting at 5.10 volts so it doesn't appear to be lacking power to display the higher resolution.

Any ideas would be great.

Thanks for everyone's help so far.

Cheers
Ryan

[mahjongg]

try using another HDMI cable, its sounds as this one is of too low quality.