I have a HP Netvista model 6276 27G which suddenly did not start up.
Checked the switch but not faulty, also cabling from this switch to
motherboard is okay. Scouted around for fuses but none found, also
not in the HIPR model HP-M14554F3 power unit. I also used another
power cable just to be sure. Switchedthe PC to 115 V and tried to
run the PC from a transformer delivering that voltage, but to no
avail. Anybody any ideas what could be wrong? Does anybody have the
connections for the cable from the PSU to the motherboard? How does
one test such a PSU? And I started out to think this was just a
simple fault
Ferry

I have a HP Netvista model 6276 27G which suddenly did not start up.
Checked the switch but not faulty, also cabling from this switch to
motherboard is okay. Scouted around for fuses but none found, also
not in the HIPR model HP-M14554F3 power unit. I also used another
power cable just to be sure. Switchedthe PC to 115 V and tried to
run the PC from a transformer delivering that voltage, but to no
avail. Anybody any ideas what could be wrong? Does anybody have the
connections for the cable from the PSU to the motherboard? How does
one test such a PSU? And I started out to think this was just a
simple fault

It is a simple fault. Most likely a diode or a transistor inside PSU failed
because of overheating. Get your HP Netvista serviced. It needs a new PSU.