Negative pole to ground voltage

Thread Starter


Joined May 15, 2019
Hi there,

I have a Yamaha PSR31 keyboard that does not turn on. I troubleshoot every component I saw, and all seemed to read normal values.
Now what's confusing me is that there is a battery voltage across the negative pole of the battery to the ground of the PCB.

When the power is connected it measures 12V across the - and + poles on the PCB. But also 12v across - and ground of the PCB!!
Is this behavior normal or am I having a short somewhere?

The board is from 1986, so it's the old PCB style where all the component are big and easy to work with.

Thank you