The APW8 that fits both T15 and S15 has an output voltage of 16.32V to 20.04V, and it costs about $100+ shipping, money wise I don't think it makes any sense to pay about 130-150 USD just to revive an old miner like the T15, it only does 23TH and consumes a good 1500-1600 watts, but that's the OP's call to make.

In my humble experience with these PSUs that Bitmain make, they are quite robust IMO, their PSUs have a lot more quality than the miners themselves, and I think I can say that at least 7-8 times out of 10 it's only a matter of PSU's fan replacement, and since you mentioned "several PSUs" I can only think that quite a good number of them only need a new fan, and those fans go for pretty cheap like $5-10, it's pretty easy to swap the PSU fan, you just need a screwdriver and a working PSU to test with.