The "color prism screen" is a GPU test that appears at the start of the boot process. It's not an under-voltage warning (unless you are running some ancient version of Raspbian, in which case, that's your problem).
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sudo apt-get update && sudo apt-get dist-upgrade -y
You are using an SDCard that's too old for the 3B+, it doesn't have compatible firmware/bootcode. The low power icon was changed to a lightning bolt some time ago. The four colour square has been retired.
When it should be booting, does the power led do 4 short flashes followed by 4 long flashes? In my experience, the undervoltage symbol with the rainbow block at that point doesn't necessarily really mean undervoltage, but can just mean that you're not running a new enough version of the operating system. It got me first time too.Brothan wrote: ↑Thu Mar 22, 2018 5:26 amHello, i have got the same problem . Picked up a new rpi3 b+ yesterday and get the color prism and the undervoltage flash , i tried a bunch of different power sources all of them working on my rpi3 b . Tried measuring the voltage and it's at 4.92 volts . Then i tried differnt SD-cards never even tries to boot on any of them ( diffrent software on al of them all updated the to the latest version ) , tried the command suggested in this tread on 2 diffrent sd-cards with rasberrian .. no boot . Could I have a hw issue ?? Im not in any words good at software or computer hw ..
A Pi3B+ will boot Jessie with the appropriate previous "treatment" -- IIRC a sufficiently recent kernel update from rpi-update. Not supported or recommended, use at your own risk, YMMV.
I guess so? I'm using the Pi 3 image found at https://retropie.org.uk/download/.
HDMI can deliver up to 200mA, so assuming the splitter was using all of that (it very likely wasn't) then you have fixed your issue by removing 0.2A of current draw.wowter wrote: ↑Wed Oct 17, 2018 8:51 pm
THANK YOU! for taking the time to post this.
I also tried a lot different chargers and cables, toshiba, apple, sony, nokia etc etc.... and a LOT of different cables, and i got the undervolt warning with every single one.
Removed the HDMI splitter, and plugged the pi into the TV directly. Warnings GONE!
The HDMI splitter takes its 5v power directly from the HDMI port, this apparantly upsets the Pi 3b+' power management (at least with cheap chines HDMI splitters.......)
No, only the splitter was causing problems. I can hook up multiple devices, using MUCH MUCH more than 0.2a:, no problems. Only the splitter is causing the issue, even with nothing else attached.Imperf3kt wrote: ↑Thu Jan 17, 2019 8:12 pm
HDMI can deliver up to 200mA, so assuming the splitter was using all of that (it very likely wasn't) then you have fixed your issue by removing 0.2A of current draw.
In my opinion, this is not fixed at all!
For an example, plug in a USB device rated at 0.2A or more