This is an intelligent reply which explains a great deal and I really appreciate it.
The reason I retained the 9v battery box was precisely so I could use the switch to reverse the polarity and run the motors back and forth directly without the sbrick for the purposes of testing.
Plus - the 9v box has some sort of current limiting do-dad inside it and I was advised to retain it to prevent blowing up the sbrick and/or motors. Having actually looked inside the box however I'm not it has one - there's not much on the PCB at all.
I will reverse the polarity and see what happens - thanks.
/ben
Sounds like you've got the polarity reversed. SBrick is powered from the 9V and 0V power supply lines, which need to be the right way round. Motors are powered from the C1 and C2 lines and take either polarity to determine which way they run.
If you're planning to make this a permanent thing, why not just splice into an extension cable and lose the battery box altogether?
Hello all
I've run into a problem with my sbrick. I had planned to power my model from a 9v mains power supply, hacked into a LEGO 9v battery box. See the picture at the link below.
https://photos.app.goo.gl/7if1Cdi8fmHELkYc7
However it doesn't work. The light on the sbrick doesn't go on when I attach it to the power supply.
The sbrick DOES work. I can power it off batteries and the light comes on and it works. Also the PSU does let me power my motors directly, so that definitely works too!
Does anyone know what it could be that my sbrick doesn't like about the PSU?
Thanks!
/ben