Old portable CRT TV power socket
Just open it up and trace the wiring. It should be pretty obvious which pin is which by matching them up with the schematic.

But even without opening it up, I'd be willing to bet that the two pins with the greater spacing from the other four are the 220VAC pins (pins 5 and 6). You can verify this by checking for continuity to the terminals of the fuse holder. You might be able to find a 2-pin line cord that fits these pins directly.

Of the remaining four, two are shorted together, so they're the +12VDC (pins 2 and 4 &mdash; this tells you which side of the connector has the even numbers).

The last two (pins 1 and 3) are ground and +12V from the internal power supply. One of them (most likely the one in the corner) will be shorted to some other ground on the chassis, such as the head of a screw, or an earphone or antenna jack. Or you could apply AC power and see which pin has +12V on it relative to the rest &mdash; that's pin 3.