Thanks Franc,

Here are the results of todays experiments.

I took another of the TA7317P I bought and carefully bent most pins so that
when I put it in the socket only pins 4,5 and 9 are in the socket.

Here's what I get:

Socket pin V, Chip pin V.

1 -16.5, -1.04
2 0.01, -1.98
3 0.01, -0.66
4 0, 0
5 -2.39 -2.39
6 76.6 -2.38
7 0, -1.29
8 0.3 0.122
9 0.3 0.3

Something tells me that this can't be a TA7317P despite its markings.

Maybe the manufacturer got it reversed in the package.
I think it should be safe to try one backwards.

Old guy