LXI (Sears) "Mystery model" 5" color AC/DC (info sought)

[Robert Grant]

I picked up this 5" LXI (Sears) set, circa 1985, I guess, at a thrift store for $8.

It works, and it has a nice bright color picture.

I was hoping to use it in my portable digital TV kludge, as I have done with a 5" B&W set, but I have complications:

There is no place to put batteries (I presume they designed it for use with a car cord, perhaps with RVs in mind).

When I bought it, it came with only an AC power cord (no DC cord).

It has a power jack on the side (pictured) with a 5 pin connector. The two-pin column is for AC, and the three-pin column is for DC (and I'm really curious why 3 pins would be used for DC), the power cord that plugs into it is also pictured. As far as I can tell, there is no mechanical switch in the socket that would have been activated by physically plugging in the cord (as I have seen on some other AC/DC devices).

So, I'm trying to find out which pins to connect -12VDC and +12VDC to. Usually, at this point, I would jot down the model number and search for a schematic or even Sears parts department for a new DC cord, but (see picture), the model number plate came off long before I got the set.

If anyone could tell me the model number of this set, or which pins to apply the 12VDC to, I can keep this American made set running into the digital age (Yes, made in USA, which surprised me for a set this small, even this age!).

Thanks, Rob