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Forum Index : Microcontroller and PC projects : Pico Computer 3 / U21

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PhenixRising
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Joined: 07/11/2023
Location: United Kingdom
Posts: 2075
Posted: 04:55pm 02 Sep 2026
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I only have a mouse connected. Does this look reasonable?
 
matherp
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Joined: 11/12/2012
Location: United Kingdom
Posts: 11809
Posted: 05:32pm 02 Sep 2026
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Have you done the usb hub mod?
 
PhenixRising
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Posted: 05:47pm 02 Sep 2026
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No. As it came but I seem to remember reading about something getting too hot?
 
matherp
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Joined: 11/12/2012
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Posted: 05:50pm 02 Sep 2026
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Without the mode the hub 3.3V regulator and the lm1117 fight each other.
 
PhenixRising
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Joined: 07/11/2023
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Posted: 05:59pm 02 Sep 2026
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They were built 21st August and I believe that I uploaded the latest files. Does it still need the mod?



Edited 2026-09-03 04:05 by PhenixRising
 
PhenixRising
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Posted: 07:43pm 02 Sep 2026
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Update. Not sure I trust this thermal imaging camera. This U21 is not what I would call hot-to-the-touch  
 
phil99

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Joined: 11/02/2018
Location: Australia
Posts: 3374
Posted: 09:52pm 02 Sep 2026
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The temperature scale at the right indicates a maximum of 54°C, which isn't hot to a fingertip. That is why testing the temperature of a baby's bathwater is done with the elbow.

The pic. nicely shows the problem with thermal cameras. The shiny heatsink tab shows up as just above ambient temperature but is actually the hottest part.
The slightly cooler black body of the regulator will have a thermal emissivity close to the value the camera is calibrated for so will be fairly accurate.
 
Bryan1

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Joined: 22/02/2006
Location: Australia
Posts: 2246
Posted: 10:36pm 02 Sep 2026
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Phenix After I had used one of my pico3's for over 8 hours straight I got my IR temp gauge which has 2 laser pointers and focused right in to the reg and pico now both showed 2C over ambient and what really surprised me was the USB hub chip which hasn't had that mod done was even cooler than the pico.

From what I read about the USB chip and it's fault is when both USB cables are used so my method have the pico in the off condition turn off the hub using the switch insert the mircoUSB while holding down the boot button and the pico is shown straight away on my computer. Now if I leave that programming cable on it will boot the pico so once the pico icon disappears from the file list on the computer the microUSB is disconnected the hub switch turned on and boot as normal.

This ensures there is no fighting of voltages so nothing gets hot  

Regards Bryan
 
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