Power plug pinout for Hitachi IA-51 1969 Solid State Television

Hi,

I have a Hitachi IA-51 Solid State Television (first manufactured in 1969, from my research). The TV was tested and worked fine on 12V last year however the power plug has recently been lost. The unit accepts either AC 220V/50Hz or 12V DC and has a weird 6-pin power socket (see attached photos, highlighted in red) at the back. There are no markings on the socket to indicate the pinout and despite extensive research I only found 2 brief articles on this unit https://www.radiomuseum.org/r/hitachi_ia_51.html and http://obsoletetellyemuseum.blogspot.com/2022/03/hitachi-ia-51-year-1969.html - none of them has the pinout for the power socket.

Assuming pin 1 is top left and pin 6 is bottom right (pin numbering also shown in photos), without opening up the unit, I measure resistance across the pins with the following results:

• 95 Ohm between pins 1 and 5, either direction
• 102 Ohm between pins 5 and 6, either direction
• Pins 1 and 6 are connected together
• Anything between 200kOhm to 3MOhm, slowly decreasing, between pins 2/3, 3/4 and 2/4, depending on probe polarity, suggesting presence of other components such as diodes or capacitors
• The four screws on the case are connected together, maybe to PCB ground. I measured a resistance of 350KOhm from the screws to pin 4.
• The rest of the pin pairs not mentioned are not connected

None of the pins are connected to other external metal parts such as antenna or knobs.

Does anyone have the manual for this unit, or at least a document telling me the pinout of the socket? Or is there a way to tell which pin is for 12V and which pin is for 220V input? I can open up the set and find out for sure, but it will be great if anyone here knows the pinout.

Thanks a lot in advance for any info.