The pHAT that doesn’t work is on a female header, the one that does work is on a male header, with a ribbon attached… I’m testing it on the one Pi, so the environment is the same.
Here’s a picture of the soldering (after I gave it another touch up) :
The soldering job looks good from here. Try the following:
sudo apt-get install i2c-tools
i2cdetect -y 1
it should output a map of i2c addresses with 0x60 highlighted. If not then that means the system can’t see it. It’s likely the case but does not hurt to check.
If so, then examine the soldering around the IC to the left of the LEDs for anything that may seem odd.
You could also, I guess measure the voltage between the pins on the header, when sitting on top of the Pi. Using http://pinout.xyz/pinout/scroll_phat, that’d be:
using pin 6 as ground reference, 5V on pin 2 and 4
using pin 6 as ground reference, 3.3V on pin 3 and 5
(technically, pin 1 is unused i.e not connected on the pHAT)
On the working one, I get the map result and voltages as expected.
On the non-working one, the map takes ages to draw and gets a “–” result on the 0x60 address. The voltages are strange, around 2.47 on the 5V pins and 4.3 off pin 3 and a negative number from pin 5!!
ah, major red face here then, I think you’ve cracked it!!
The one in the middle, I was setting up for a friend and just wanted to test it, but now I can see that the two rows of pins are swapped by the right-angle male header on the Pi… the one with the ribbon cable is a project for myself (work in progress) :
and confirmed after putting the pHAT on to a Pi with a regular male header, it works fine!