I use a Nano to drive a camera slider. I managed to get that working when the components are connected via wires. Because of the clutter in a smal box I decided to create a PCB in KiCad. I now have the PCB, soldered all components, and the input voltage (9V battery) drops immediately to almost zero after the DC jacket. As I'm a noob with electronics i have no clue what can be wrong.
The schematic:
Get your meter out and check the power jack to see if it is wired backwards. The + going to board ground.
Thanks for your reply Paul.
I checked the polarity many times. When I put the probes on the rear and side connections of the DC jack, I get a very low voltage. When I put the probes on the rear connection of the jack and the barrel of the battery plug, it reads normal voltage.
If that barrel jack is wired the way I'd expect it to be, ground will on the bottom connector in the picture (closest to the board edge), not the side connector.
There is continuity between the side and bottom connectors.
A 9V battery cannot run a motor. Did you test your prototype "wired" circuit with 9V battery also?
Yes, and it worked like a charm.
Fyi: no lights come up when connecting the battery. With a suitable adapter also no lights. Only when powering via USB.
Hi,
Can you please post EXPORTED jpg images of your PCB?
Have you connected your DC 9V to an unpopulated PCB and checked the voltages where the supply should go?
Do you have the same problem with an unpopulated PCB?
Can you please post link to specs/data of your motor?
Thanks.. Tom... 
Good questions Thom! Thanks.
I will follow your suggestions and be back. Give me some time.
I soldered a DC jack to an empty PCB and had the same problem. I then removed the side connector of the DC jack and connected the bottom connector to ground and voila: things started to work. Except the motor driver but that's a different problem.
So van_der_decken was right and I discovered it by Ton's suggestion. Thanks!
In a normal 3 pin jack, they are connected together when no connector is inserted, but when a connecter is inserted, ground is on the bottom connector and the side connector is disconnected from it.
That explains everything. Thanks.
Thank you bobcousins, I will use that one.
I now have it working but the motor stops under load. It did work with the wires. Would doubling the tracks width on the PCB be a solution? Or do I need to power the motor seperately?
The stepper motor is a 28BYJ-48 5V and ULN2003 driver board.
Easily verified by measuring the voltage drop from one end of the trace to the other.
The problem was mechanical. Too much strain on the spindle.
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