Roland Rhodes 660 power

I have a Roland Rhodes 660 that do not power seam to have a short I metered positive and negative and they are definitely in short circuit I test the continuity with the multimeter. on the motherboard. and they seams to be in shot circuit before the power switch…? any inputs?

i do not believe is the 5 volt regulator because in the input most right pin both the positive and negative meet…but I’m no expert in keyboards ,but learning .

thanks you for the help, love the YouTube channel.

last night i found the problem was a Zener diode , there are two zener diodes visibles around the power area, one is just at the output of the 5v regulator, i replace the other one, the one that at the side of a tiny transformer type of device with two coils inside…? and then it works perfect. now fixing the buttons and 3 springs on the keys ,I’m very happy bring this one back to life .
thank you for the channel help me go back in to keyboards and like it .