Automation pHat low 5V


I have two new Automation pHats and a new Pi 3 B v1.2 Neither pHat works properly with the sample “read inputs” program when plugged in bare with no wires or other equipment attached. The pHat is detected but the _update deamon throws an IOError and dies. When I check the voltages on the pHat (header and outputs) the 3.3V is nominal but the 5V is less than 0.5V. With no pHat connected both 3.3V and 5V are nominal at the header. I’m using a 2.5A “official” supply and the Pi 3 shows no other operational problems.

  1. What quiescent current should the pHat draw on 3.3V and 5V lines?
  2. Is there anything else I could look at?


What are your soldering skills like? Solder joints look OK? Assuming you didn’t use a hemmer header.


OK, I guess. It was the first thing I checked. Also, when the first board didn’t work, I redid all the soldering. When the second board failed with exactly the same symptoms, that seemed to reject the idea that I had made a bad joint on a pHat. Unfortunately I don’t have another B version Pi to check that the problem isn’t on the Pi board (as in, soldering of the header pins, for example).


Ok, I had to ask. ;) Especially for pHats that come with the header not soldered on. Everything except the Zero comes with the GPIO header pre soldered. I wouldn’t suspect an issue that way, unless you see an obvious solder bridge. It could be the Pi, but a soldering issue is , IMHO, unlikely. It could be that the first automation pHat has a fault that did something to the Pi? Just guessing really though. Do you have another different pHat or Hat to try on that Pi? Any Pi with a 40 pin GPIO can be used to test those pHats. A+, B+, Zero etc.


Unfortunately I have no other Hats or pHats or Pi + models (I wrote B version before, by mistake). Hopefully, someone will know what the quiescent supply currents of this pHat should be and I can check that.


Problem solved.

It was a bad software install (via the Pimoroni dashboard).
I reinstalled direct (curl … | bash ) and its OK now. Even the 5V out is now nominal!

NB 1 : The symptoms I got were were the same as you get from the sample software with NO automation pHat (or Hat) plugged on.

NB 2: See also GitHub “Problems with Raspbian #10” stefancrain June 24


Nice to hear its solved, and how you fixed it. Will keep that in mind. I’ve used the dashboard a few times. pHat Beat and Explorer pHat.