constant hum in Sansui SR-222 MK V turntable

[freedrome]

Hi,
I'm experiencing a very irritating constant hum on my newly arrived Sansui SR-222 MK V turntable. Seems like a cable issue but I can't figure out where. The TT is grounded to the amplifier (Audiolab 8000A).
I even opened it and in its simplicity nothing seems wrong or visible oxidation.
The cartridge is new and the cables are plastic shielded.
The hum is present even if the turnable is not connected to the power but much lower in volume. Simply switching to PHONO and there it is.
Anyone has ANY idea where the hum comes from?
Sending some pics.
IMG-20200725-145531 — ImgBB
IMG-20200725-145547 — ImgBB
IMG-20200725-201600 — ImgBB
IMG-20200726-110647 — ImgBB
IMG-20200726-110705 — ImgBB
https://ibb.co/GHKfDcN

 

[JonSnell Electronic]

The arm has no ground. I would connect a flexible ground wire as the white line depicts, or maybe the other fixing point and check it grounds the arm metalwork.

 

[freedrome]

Thank you for the hint!
I did a quick search and I noticed one that doesn't have the arm grounded
platine-vinyle-sansui-sr-222-mkv-20 — ImgBB
and another that probably does (the white cable) right?
s-l1600-2 — ImgBB

 

[freedrome]

Actually, there are 2 black cables coming out of the tone arm and they are ground connected...

 

[Jazid]

Actually, there are 2 black cables coming out of the tone arm and they are ground connected...

... But maybe its not earthing the arm tube? Hum can be difficult to pin down, is it as loud as the music, or annoying background, 50 or 100 Hz?
After Jon's suggestion and if its background level then you could try moving the t/t or even just the arm around since it may be picking up stray transformer fields. Also what is the cartridge? Some are well known for picking up hum, others much better in that regard.

 

[freedrome]

There was a breakage in the ground wire. I fixed that by changing it.
thanks