Lights but no sound

Using Raspberry Pi b v3 running latest raspbian stretch and I have got the speaker phat flashing lights at me during test but no sound.
I have not soldered the female header as I need to access the GPIO pins for another project on the same Raspberry but have connected via “jumper cables”.
Please advise which cable/s may be suspect allowing no sound even though I get the sound bar lights to flicker.

How are you connecting the jumper wires if there’s no header?

Jumper cables after reading the requisit web page at

Have you soldered the jumper wires to the Speaker pHAT for a reliable electrical connection?

Have you connected the grounds - physical pins 6, 9, 14, 20, 25, 30, 34 and 39 - as indicated on Pinout?

I have connected ground to pin 6 but not soldered till I am confident that I have it correct.

You mentioned all the ground pins but I have only used one as I believe that all ground pins are connected to each other anyway or did you list them all for me to select one.?

The ground pins are connected together on the Pi side of things, but not necessarily on the pHAT itself. Usually routing is pretty constrained and the ground plane gets broken into sections that it relies on the Pi to link together.

In the case of Speaker pHAT, though, it looks like there’s an unbroken ground plane across the unpopulated top of the board. I’d say you should connect at least physical pin 9 and physical pin 39 to ensure a decent ground return path from the two ICs at extreme ends of the board.

Pinout will usually list all the grounds if there’s any doubt about which are used.

OK I have connected 9 and 39 but still I get lights but no sound

How are you ensuring a reliable connection on the i2s lines? I’m picturing male jumper jerky just pokes through the holes intended for the header? Am I right, or getting the wrong end of the stick?

I think that you may be correct and maybe I should use the 40 pin header to connect pHat to Raspberry and as I only need ground and two other pins for my other project, solder those onto the pHat when I have got the pHat working correctly.

That may be an easier approach. Both the i2c and i2s connections on Speaker pHAT may suffer reliability issues from being at the end of wires.

This might come in handy:

OK That did it. I now have lights and sound.