Pukse-mode Power Supply compatibility



I have a Socket A motherbousd with power supply that gives only 1/10th volt pulses (one/sec) on its output.
Can I swap this non=wkg supply with one that DOPES work (same volts, amps, wats amd ATX plug to motherboard?
All the wires except two are the same colour.
Can supplies be tested when UNPLUGGED from motherboard?
How do I simulate the motherboard feedbaxk signals (overvolt, overcurrent etc) and how to tell if it is THESE signals that prevent the “non=wkg” power supply turning on

Thank you for your help