Upgrading an old PI3 setup that has a PI3 with HIFIBerry DAC+ and V1.1 screen to a PI5. As of this moment I only have the PI4 power supply and was wondering if anybody has a similar setup. I replaced the PI3 with the PI5 and added a header extender then doubled up the DAC standoffs to lift the dac away from the PI5 heat sink. Unfortunately I didn’t do my homework and don’t have the DSI FPC cable for the screen (ordered from Core but don’t have yet) so can’t test it. With the PI3 I could run the supply to either the PI3 board or the screen board to power the setup with no issues.
I have 2 questions-
1 - Will the PI4 power supply be sufficient to run this?
2 - What would happen if I ran the PI4 supply to the PI5 board and the PI3 supply to the screen board at the same time?
Hi @Steven - welcome to the forums 
I’ve done some research on the screen’s power requirements and according to this forum post
The display consumption alone is about 550mA at 5V.
So a Pi 5 may be right on the limit of what the Pi4 PSU can provide. Until the official Pi 5 supplies are available it is likely you will need to investigate an alternative method of powering the display.
If that’s the case then on to question 2. The screen board has its own power connector so if i was to plug the PI3 supply into that and plug the PI4 supply into the PI5 board will that work? Currently the screen gets its power from the PI through the power leads from the DAC (see pic 1 above). If I unplug them then that should work…maybe. The only connection then from the screen board to the PI would be the ribbon cable and I don’t know if that supplies power as well as video.
As far as I’m aware that’s just a video signal.
Yes it ought to. A common ground connection will be provided by the video ribbon cable, but you can also connect the ground of your two power supplies separately to be doubly sure by eg. connecting the ground of the display to a ground on the Pi’s GPIO header.
OK so got the ribbon cable and hooked it up. Removed old power connection from the hat to the screen board and used the PI3 power supply to run the screen. Works fine but hit a snag with the screen orientation. The original pi3 kit with the screen came with the stand upside down. To fix it you added lcd_rotate=2 to the config.txt file. that does not work in the pi5. Although you can rotate the display in the gui it does not rotate the touch screen with the display. Any way to do that?.
It looks like this is a common issue many people have experienced in the past. Not just isolated to RPi 5
Here’s a promising thread which may solve the issue.
