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I got a new RPi Zero W :) Fresh installed Raspbian Jessy on a new 16GB SD. All went good, including connection to wifi, and Logitec 2.4GHz mouse and keyboard.

after that- from time to time, screen flickers for about 1s, every 2-3 min. I tried you set a defined screen res - no help. I even set display driver- to No GL ( basic ) - no help

Any ideas what may cause it ?

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I had a similar problem but with plain RPi Zero. Turned out to be a power issue. There's also a video https://www.youtube.com/watch?v=3IHBcIwk-Bo

  • I'll try to replace power source, BUT, I bought also a regular Zero, used the same SD, and it works fine (no flickering). – Guy . D Aug 24 '17 at 20:29
  • The Zero W uses more power than the Zero. Your power supply is probably very close to overloaded with the Zero W. – Craig Aug 24 '17 at 22:24
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I'm not sure what a "defined screen res" is, but if you have a poor / excessively long HDMI cable, then setting a lower screen resolution should help because a slower clock over a long cable will be more stable.

Using a shorter or better quality HDMI cable (if you have one) should help too, as well as eliminating any HDMI adapters / splitters / multiplexers, if you happen to use any.

There is also config_hdmi_boost in config.txt:

Configures the signal strength of the HDMI interface. The minimum value is 0 and the maximum is 11.

The default value for the original Model B and A is 2. The default value for the Model B+ and all later models is 5.

If you are seeing HDMI issues (speckling, interference) then try 7. Very long HDMI cables may need up to 11, but values this high should not be used unless absolutely necessary.

Remember that if you want to boost the HDMI signal strength, you should not use hdmi_safe=1 as it sets config_hdmi_boost=4.

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I never did find a way to fix this, but in my case it seems to be some kind of heat issue. As in too cold, not too hot. The longer the Pi is in use, the less it blinks. This could still be a power source issue, of course, since the power source might be affected by heat.

I got my Pi from a CanaKit starter kit which includes a plug-in power supply, a case, and a fan for the case, which I am using. The case never gets noticeably hot, but of course that has nothing to do with the transformer which is plugged into the wall under my desk.

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