Picade PSU marginal with RPI4 & 10 inch screen

I’ve recently built up a newly bought 10" Picade with a 4Gb RPI4.

Having got Retropie up and running I noticed at times the screen would drop out, coming back with the HDMI message at the top left. Lowering the sound volume reduced the incidence. I wondered if the power supply on the Xhat was browning out. In the first trials I had a small wired keyboard and a 32Gb USB stick plugged into the RPI USB ports.

Later trials with nothing extra plugged into the USB ports didn’t suffer the same problems of screen dropout.

How much margin is there on the supply to 10" Picade with an RPI4?

Have a look at this
Are you using any illuminated plasma buttons?
Do you have the newer XHAT with the USB C power jack? That should give you 3A to play with if your using the official Pi 4 power supply.
If its the older card with the Mico USB your looking at 2.5A available, assuming your using the original Pi 3 power supply.

EDIT: If you are hitting the current limit you should be seeing a low voltage warning on the monitor. Low voltage is a side effect of the power supply reaching its max current limit. If will be a flashing lightning bolt.

I’m not using any illuminated buttons. It is the standard 10" Picade received two weeks ago including the new USB-C XHAT.

The symptom I get is that the screen blacks out, then you see the HDMI logo at the top left of the screen. Sound continues as this happens and when the screen is fully back to life it is clear that the RPI has happily continued through the blackout. Its as if the screen is resetting.

I have not seen the low voltage warning.

I would shut down and double check that the ribbon cable going from the screen to the display driver board is in correctly. I’d also check that the HDMI cable is firmly connected. And that the USB power cable is in tight.