For people in Klang and Shah Alam:

Hup Soon Auto & Electric
7, Lorong Selampit 18A, Taman Desa Utama, Klang
03-33238588

Reliable old uncle. Typical oltimer mechanic, so don't expect to be chatty and nice.

Vios alternator was the issue and everyone wanted to cheat by asking to change it.

I have some background knowledge but (big but) did not have the time to open and inspect so my father took the vios there.
Oltimer mechanic said this:

Carbon losak (worn out). Kapla manyak koto wo (dusty on the top)
He used blower and sand papered the coil bearing. Replaced carbon 1 set original Japan.

Voltmeter reading showed 13.9 with engine on and even touch 14.0. With load (lights and AC) it was 13.7.

He charged RM120.

p/s: FYI, I would advise old cars with grounding issues or even without grounding issues, please make sure to properly ground body and engine block to avoid future problems.