If you know that there are no phono boards, just connect any old line level source to the phono inputs you are asking about. Turn the selector nob or button to the corresponding input, and if music comes out there is a straight-through wire and you are OK. If you can't hear anything, you'll have to either fit straight-through boards or solder in a bit of wire. Open it, and if you see the ends of a clipped wire join them back together again with a small blob of solder.
I've not seen inside a 102, only inside a 92 and a 72, but this sounds logical.