1990 300zx 2+2 charging system short

[FireThrow13]

Alright it’s what the title says
I bought this car a couple months ago and did the timing and the 120k service stuff, and the entire time it’s been on an old weak battery that never held charge so the short hasn’t been that prominent. Recently I got a new battery because I was close to getting it all finished up but when I plugged it in there was smoke from the general area of the bottom of the battery. I’m not totally sure where the smoke/smell came from but it was in that general area.
I got a meter and tested continuity from the positive connector and negative and that is a closed circuit without the other wire on the positive terminal that leads to the fuse box right at the battery.
However when the probes are connected to the smaller wire to the fuse box and the negative connector there is an open circuit/short.
I pulled the fuses in that box and narrowed it down to a short in the charging system.
The continuity is broke when the fusible link and the LTG fuse are pulled, whatever that is. But I did follow the wiring diagram and it led me to the charging system.
From here I’m not really sure what to do
Bad alternator? I looked under and at the alternator and I haven’t noticed anything wrong or out of place wire wise.
So my next step would be to test the alternator and see if that is the short.
There’s a video where the guy disconnected one of the wires to the alternator and connects them with two wires and checks if the amps rise but he didn’t give much information in how he did it but I guess that could be a troubleshooting step for me if any of you guys know what he did and how. I can provide the YouTube link if you want to check it out for yourselves.

So basically

What do I do!?

[VStar650CL]

That test you were looking at is to see if the field coils are healthy, not to test for a short. To make smoke the short has to be pretty severe, so if it's in the alternator it's a collapsed brush or something else catastrophic. See if the short goes away with the main alternator terminal disconnected. If not, see if it goes away with everything else on the alternator disconnected. If either of those kills the short, the alternator is bad. If not, with the alternator still disconnected, disconnect the alternator main fusible link and ohm from the alternator main wire to the block. That should read infinity (or at least megohms). If not, there's likely a short in your old wiring. If that tests good, your short is elsewhere.

[FireThrow13]

To make smoke the short has to be pretty severe, so if it's in the alternator it's a collapsed brush or something else catastrophic.

It was the alternator, bad diodes!! Still don’t know why it smoked. I have some other electrical gremlins regarding the AC but ill make another post of it in the right “technical” forum lol

[NolimitZ32]

Have you confirmed it was the alternator or did the alternator test bad and you haven't confirmed that the short is gone? I ask because there is a large power wire that runs in the loom under the top of the core support that I had short on one of my Z32, the insulation rubbed through and was arcing straight to the core support. There are other accounts of the same thing so mine wasn't an isolated incident.