I've had a Dragon 32 sitting on my shelf for years now, I've never actually gotten around to building a power supply to test it. If memory serves it needs multiple voltages feeding to it over a DIN connector.
If you've lost the supply brick; that's strictly the AC side of things, it is just a transformer in a plastic wrapper.
The outputs of the transformer are connected to a DB-9, the pinout is:
1,6----8.5V----2,7
3--14V--CT--14V--5
Keep an eye on the large capacitor on the powersupply board, they tend to go bad, look for white stuff near the caps, if you find any replace them before trying to power it all up.
You can pull fairly decent composite video off the input to the modulator (on the PSU board).
Good luck!
(Sorry I know that seems tight but I'm out of work right now).
p.s. They are D plugs.. look like female joystick ports..