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

 

More than a short it seems there is an open circuit.

 

More than a short it seems there is an open circuit.

That's a relief at some point. What could cause such an open circuit among these component? Resistors, capacitor, diodes, IC?

 

That's a relief at some point. What could cause such an open circuit among these component? Resistors, capacitor, diodes, IC?

Loose wire, PCB's trace cut somewhere or something needing resoldering.