Flickering screen on Pi Zero W

[chubsta]

I am very new to this, having bought my first Pi last week so may be missing something obvious...

anyway, got one of the new Pi Zero W today and did my first proper 'install' - i tried using a readymade image but that didn't work so installed a Raspbian Jesse Lite and installed RP over the top - bit of a faff as i didn't know how to setup the wifi etc, but got there in the end!

Trouble is, right from the start i have suffered from the screen constantly blanking out or flickering, seemingly whenever the pi is trying to do something. After much research i have changed the config file to boost the hdmi (up to 11!) and it seems to have made a slight difference but it is still unusable. The problem still occurs even when nothing is plugged into the usb socket, and plugging either a joypad or keyboard in does not change the frequency of the dropouts.

I am using the same power supply i was using with my Pi3 and had no problems with that at all so don't think that is the issue - unfortunately my multi-meter is broken so cant check voltages on the pi itself.

Given that i thought the zero had lower power-supply demands than the 3 i would be very surprised if that is the issue so any and all advice would be appreciated!

[obsidianspider]

What kind of HDMI cable connection are you using? An adapter with a cable plugged into it? What resolution is the TV? You shouldn't have to do anything funky with at Zero to get it to work with HDMI, but I don't have a Zero W. (yet)

[chubsta]

it is the same hdmi that i use with the Pi3, but this time plugged in via an adapter (I have ordered a hdmi-minihdmi cable which should hopefully be here in a couple of days.

The tv resolution is 1920x1080p (it upscales to 4k i think as it is a new 65" job) - i will try on my old 1920x1080p tv later today hopefully.

[obsidianspider]

@chubsta If I recall correctly the Zero will try to output 640x480 (even over HDMI) by default. I had that issue with mine, now that I'm thinking back. I'm looking through my notes to see how I addressed that and will post back.

[chubsta]

Small update - by enabling hdmi_safe=1 in config.txt I get a stable image on the TV, but of course the resolution is very poor.

i guess from this it means the power supply can be ruled out as a problem, and i would also guess the hdmi cable is ok too as it is one i have removed from my PS4 which displays 1080p no problem...

[obsidianspider]

I found a link that talks about manually setting 1080p.

hdmi_force_hotplug=1
hdmi_drive=1
hdmi_mode=16
disable_overscan=1

hdmi_mode=16 is 1080p. What I'm not sure of is how it would handle being plugged into a 720p screen, but if that's not a concern, then you should be ok.

Here's a link with all sorts of settings that can be put in config.txt and their meanings.

[chubsta]

Well, I wont say this is solved but it is not a problem anymore - I connected the Pi0 to a different tv (51" 1080p) and it works fine, there is no flickering at all, fortunately for me this is the tv that the Pi will be connected to permanently, i was only using the other TV as it was more convenient when setting stuff up!

I guess there is the possibility that the original TV, being 4k, may have been trying to upscale the Pi signal, causing the flickering? Anyone any experience or knowledge of this?

[Tina]

Hi, I had a similar problem. It appears I have solved it by forcing the monitor to use HDMI input in the settings as opposed to autodetect. Hope this helps people encountering this issue in the future ;D
Cheers,
Tina^^