Dataframe XP 30 Power Supply won't start

I have an old Supermac dataframe xp 30 external scsi hard drive case. I wanted to use the power supply to power hard drives without having to plug them in to a case power supply.

I pulled the switching power supply out of its case and went to test it. The PS would not start and would just pulse, causing the fan to twitch and pulse on and off. I had not powered the device on in 10 plus years.

To make this very short after much testing I found that the power supply MUST have a considerable load on it, or it will not start. The fan and LED are not enough. Connecting a hard drive to it and it powered up fine.

Also the following items can be replaced with other components as listed:

2SK538 N channel Mosfet can be replaced with an FQP9N90C.

UA431 Adjustable Precision Shunt Regulator can be replaced with a TL431 or KA431.

The Blue POT VR1 adjusts the 12 volt power supply.

I do not know the ratings of the power supply but the hard drive in it was rated at 1 amp on the 5 volt supply and .68 amps on the 12 volt. I suspect it may be able to handle 2 amps on both but have not tested it.