MrDitchy
Posts: 8
Joined: Thu May 23, 2019 5:42 pm

Pi 4 hangs on boot when 2 displays connected

Fri Jul 26, 2019 9:12 pm

Hi, I have a 1GB Pi 4 that will work perfectly on either my little portable TV (720p) or my computer monitor (1080p). However if I connect both screens I get the rainbow square on both then the 4 Raspberrys on the monitor connected to HDMI 0 and then nothing. If I power down and remove the cable from HDMI 1 it boots perfctly to whichever monitor is connected. I am at a loss as to why. I am also a beginner with Raspian so I will need clear instructions on how to input any help that can be offered. Thanks in advance.

pfletch101
Posts: 510
Joined: Sat Feb 24, 2018 4:09 am
Location: Illinois, USA

Re: Pi 4 hangs on boot when 2 displays connected

Sat Jul 27, 2019 12:51 am

What are you using to power your Pi? This sounds like a power supply problem.

MrDitchy
Posts: 8
Joined: Thu May 23, 2019 5:42 pm

Re: Pi 4 hangs on boot when 2 displays connected

Sat Jul 27, 2019 4:31 am

Hi Its a 5.1 volt 3 amp supply that i am using.
Last edited by MrDitchy on Sat Jul 27, 2019 4:54 am, edited 1 time in total.

MrDitchy
Posts: 8
Joined: Thu May 23, 2019 5:42 pm

Re: Pi 4 hangs on boot when 2 displays connected

Sat Jul 27, 2019 4:54 am

I have just tried another TV this time a 1080p model I get a no signal although my monitor on HDMI 1 appeared with just the trash can suggesting that it may a lack of power from the HDMI output. I will try and get a second computer monitor and see if that cures the problem. Again on boot both screens had the rainbow square.

So I booted the PI and then plugged the second screen(my 720p TV) into the HDMI 1 and now it works as the second screen. It may hang when booting but at least it works.
Cheers

pfletch101
Posts: 510
Joined: Sat Feb 24, 2018 4:09 am
Location: Illinois, USA

Re: Pi 4 hangs on boot when 2 displays connected

Sat Jul 27, 2019 1:25 pm

MrDitchy wrote:
Sat Jul 27, 2019 4:54 am
I have just tried another TV this time a 1080p model I get a no signal although my monitor on HDMI 1 appeared with just the trash can suggesting that it may a lack of power from the HDMI output. I will try and get a second computer monitor and see if that cures the problem. Again on boot both screens had the rainbow square.

So I booted the PI and then plugged the second screen(my 720p TV) into the HDMI 1 and now it works as the second screen. It may hang when booting but at least it works.
Cheers
"A 5.1 V 3A supply" does not really answer the question I asked. This board is full of descriptions of problems caused by 'power supplies' which are really battery chargers and are unable to maintain their rated voltage and current simultaneously. I strongly suggest that you try getting and using the 'Official' Pi 4 power supply.

MrDitchy
Posts: 8
Joined: Thu May 23, 2019 5:42 pm

Re: Pi 4 hangs on boot when 2 displays connected

Sun Jul 28, 2019 6:26 pm

Hi,The power supply came from an approved re-seller as part of a kit, so I hoped that it was fit for purpose. My intention is to buy an official supply just as soon as they are back in stock with an Australian plug.

pfletch101
Posts: 510
Joined: Sat Feb 24, 2018 4:09 am
Location: Illinois, USA

Re: Pi 4 hangs on boot when 2 displays connected

Sun Jul 28, 2019 7:16 pm

MrDitchy wrote:
Sun Jul 28, 2019 6:26 pm
Hi,The power supply came from an approved re-seller as part of a kit, so I hoped that it was fit for purpose. My intention is to buy an official supply just as soon as they are back in stock with an Australian plug.
My first Pi setup (3B) was bought "from an approved re-seller as part of a kit", and, although it initially seemed to be OK, the power supply started getting flaky after a few weeks. I do have one other non-official power supply that seems to be reliable, but my two official ones have never given me a moment's concern. My new Pi4 (when it is delivered - sigh!!) will have an official supply.

MrDitchy
Posts: 8
Joined: Thu May 23, 2019 5:42 pm

Re: Pi 4 hangs on boot when 2 displays connected

Sun Jul 28, 2019 8:03 pm

As soon as i get an official supply I will post an update. Cheers

MrDitchy
Posts: 8
Joined: Thu May 23, 2019 5:42 pm

Re: Pi 4 hangs on boot when 2 displays connected

Tue Aug 13, 2019 5:05 pm

Several items have arrived since my last post. A new 4 GB Pi, a new case and finally an official power supply. I assembled my 4 GB Pi into it's new case and transferred the SD card from my 1 GB Pi and ran it on a single monitor. Later I flashed a new micro SD and placed it in the 1 GB PI. A few days later my new official power supply arrived. I connected it to my 1 GB Pi hooked up the second monitor and it all worked. Then I tried with my 4 GB pi and ran into the same problem a hang on boot when 2 displays are connected. The only common component at this point was the micro SD card. I swapped the micro SD cards between the two Pi's and now my 4 GB Pi boots with both displays connected. I then tried with my old power supply and that also was able to boot the Pi with both displays connected. Both cards are up to date. I try to update as soon as I can.

So to cut a long story short, if your Pi 4 hangs on boot when 2 displays are connected, try a different micro SD card. The cards are different brands, the cheaper of the two is the one that allows the dual displays to work.

pfletch101
Posts: 510
Joined: Sat Feb 24, 2018 4:09 am
Location: Illinois, USA

Re: Pi 4 hangs on boot when 2 displays connected

Tue Aug 13, 2019 5:46 pm

MrDitchy wrote:
Tue Aug 13, 2019 5:05 pm
So to cut a long story short, if your Pi 4 hangs on boot when 2 displays are connected, try a different micro SD card. The cards are different brands, the cheaper of the two is the one that allows the dual displays to work.
It seems highly improbable (but not impossible, I grant) that the make or specs of the system SD card is the cause of this. If I wanted to test this, I would clone the 'non-booting' (on the Pi4) system to the 'booting' SD card. My prediction is that the clone of the 'non-booting' system to the 'booting' SD card would not boot with two monitors connected, and that there is a system software difference between the two. Both being up to date does not rule this out.

MrDitchy
Posts: 8
Joined: Thu May 23, 2019 5:42 pm

Re: Pi 4 hangs on boot when 2 displays connected

Wed Aug 14, 2019 6:53 am

I'm just glad that it all works properly. I guess that a software difference is the most probable cause, although it would be a lot of work to prove the theory.

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