Volvo Repair: 240 DL Charging problem, pulling out my hair, ground connections

Question
1990 240dl, a/c, manual.
Dash lights, idiot, began flickering, volt meter reading about 12 volts. I replaced the alternator and now the idiot lights are on bright. Not charging at all. Starts and runs fine. 220k miles. All inside fuses are fine. The 25Amp fuse on battery side is fine. Tested the alternator before I left place of purchase. The alternator, as I understand it, has the voltage regulator built in. But what is the gizmo next to the 25Amp fuse and beside what looks like a positive junction box? 2.25"x1.25"x1.5" metal covered box with all red wires entering it. Looks like a relay box. Part # R601.323 12Vbis250W ?

Pulling out my hair, rapidly going bald.

Thanks,

Trent

Answer
Check the one red wire at back of alternator and be sure it is not grounding out somewhere. Follow the wire and check to see no worn insulation.

Gizmo you're talking about is just junction, not related to charging system.

Also be sure you're getting good ground connections, at block , at body and battery