Zero horizontal artifact lines


#1

Just got my Pi Zero and just wondered is it just me or is there a problem on 1080p with artifcat problems.

Generally there are green pixels on the screen that depending on application on mouse position become horizontal lines.
I have sort of seen similar with broken graphics cards where the ram might be dodgy.

Its a great little card for only £4:00 and its not the worst thing in the world.
But I wondered is this just me?


#2

Yeah messed around with config.txt and rebooted.
Tried increasing the hdmi output as it said it might stop interference but no different.
set it to hdmi safe mode and apart from the blocky icons no interference/ artefacts.

Anyone any ideas?


#3

Hi,

Just after some quick pointers as have read a lot about the HDMI modes but its not that the screen is displaying a wrong resolution.

There is a green shimmer of occasional pixels and windows at a certain position on the screen will create these horizontal green lines.
I dunno if I am having a brain fart but is this more likely to be dodgy ram mapping to the display?
Its a Pi Zero B that I just got out of interest and its no biggie, but if it is just me being dumb then no probs.

The noobs, boot screens are perfect its only when it jumps to 1080p on a viewsonic VX2370SM monitor as haven’t been able to test it on anything else.
Is that scan rate and I need to hardcode the mode?
In safe mode it works fine.
Tried upping the hdmi output, no go.

Even set the mode to 16 which is right.

Okay an update and I am totally confused.
The monitor has a DVI input and I have a HDMI non active to DVI convertor (no sound)
Use the same HDMI cable but into DVI no green shimmering dots, put it back in HDMI and green shimmering.
Use the same cable from my PC to HDMI perfect no shimmering !!! Doh that one has got me?


#4

Have tried increasing the video RAM, open rasp-config, you will find it in the menu


#5

I have got it sorted nothing to do with ram.

The example in config.txt is config_hdmi_boost=4

Which stupidily I took for the highest safe value.

http://elinux.org/R-Pi_Troubleshooting#Interference_visible_on_a_HDMI_or_DVI_monitor

In the above “You may experiment with different values of config_hdmi_boost. The default is 2 for Pi1 model A/B, and 5 for newer Pi’s (B+, Pi2, Pi3). At your own risk, you can go up to 11.”

Made me assume it was similar to overclocking the HDMI vcore or something but apparently its a EMF problem more than anything where you can run at 11 safely just migt be throwing out interference.

I have config.txt config_hdmi_boost=7 with just the odd green pixel shimmer.
It good enough and actually hard to notice.

Still don’t understand how the same cable with a passive DVI convertor works and the same HDMI cable straight doesn’t as the signal difference must be tiny, maybe slightly worn conacts… ? Just dunno :)