Unknown needed voltages to turn on Amstrad PC 5286

Greetings to all. I've an old Amstrad PC5286 that has the power supply damaged. I tried to fix it but I lost a lot of time. Then, I decided making a new power supply based on a modern pico ATX power supply. But I don't know what are the output voltages.



These are the conectors in the motherboard:


The power supply have two connectors as you can see in the photo. In the big connector, I supose the following voltages: +5, +5, ground, ground, +12.
But in small one I haven't any idea, probably negative voltages?

I've looked for service manuals, forums etc. but I haven't found anything. Can you help me with it, please?

 

Perhaps too late for you but may be useful to somebody. These measurements were taken from my power supply which seems to have an intermittent fault (so trust these at your own risk).
Main connector:
Purple 5.3V
Black 0V
Yellow 12V

4 pin connector (From red pin->)
Red -5.1V
Grey -12.1V
Grey 0V
Grey +5.25V

3 pin connector (to HDD)
Black 0V
Brown 12V
Red 5.2V