Vewlix AC Grounds

[adgenet]

The Vewlix has a three prong AC supply receptacle, with the ground pin wired directly to the chassis. Aside from this general chassis ground, the only component that is actually tied to ground are the service outlets.

There is an input noise filter that has provisions for ground, but they are not connected.
Same goes for the 12V and 24V supplies, as well as the jvs supply mounted on the mdf board. In fact, the wire harness (A, A1, A2), does not even contain a ground wire despite there being ground terminals on the power supplies. Is there a technical reason Taito designed these to be floating (supplies) or not connected at all (the noise filter)?

What consequences would there be by tying all of these to the main chassis ground point?

Relevant diagram:

 

[adgenet]

I contacted TDK-Lambda about this sort of configuration (mentioning the wooden board the supplies are mounted on), and they said: "Earth ground of the supply is meant to be connected directly to an earth grounded chassis".
While I'm sure Taito has a reason to not do so, I can only guess that it is to reduce cost. Wire and connectors do cost money after all, and maybe they think the input fuse, wooden board, or the protection functions of the power supplies are enough to isolate any danger, though I would disagree. We may never know.

Either way, with this information, I see no reason to leave the FG connections on the power supplies unconnected and have since connected my FG terminals on my supplies to the main chassis ground.I have also attached the noise filter ground connection to the main chassis ground point. Nothing has overheated, exploded, caught fire, or melted.

While unrelated to the original question, I also asked about whether or not it is acceptable to attach the DC (-) to FG (this is usually the case on most ATX power supplies). They said that it is acceptable to do so.
Further online research suggests that the only reason not to do this would be if you require a floating DC output to combine with other supplies in series or parallel to increase current capability or special voltages. Other sources suggest that leaving the output floating would keep noise down and is critical for noise sensitive instrumentation.
I am undecided but may end up tying DC (-) to ground as I believe many components that use these supplies do end up having some part of their DC (-) circuit attached to the cabinet frame, so why not do it at the source?

 

[jassin000]

I am undecided but may end up tying DC (-) to ground as I believe many components that use these supplies do end up having some part of their DC (-) circuit attached to the cabinet frame, so why not do it at the source?

Look most of what you are saying go's above my head, but I do know this... The body of the Vewlix cab IS tied to earth ground, if you also connected DC - to the cab you would in effect be tieing a DC supply to a earth ground.

I was told NEVER to do this, and NO parts of the Vewlix DC supplies are tired to earth ground in any way (I believe the proper term is signal or device ground, but not earth ground).
The cabs DC supplies do share a common DC device ground, but this is NOT earth ground (thus it is NOT connected to the cab body).

Hopefully someone with a better understanding will further expand on this.

 

[adgenet]

Thanks for the input.
Your assessment of the stock configuration of the vewlix is correct. You are also correct that tying DC (-) to ground is tying to earth.

I have also come across conflicting opinions online about whether or not doing this is the "correct" way.
That said, as I mentioned above, atx power supplies do in fact connect the DC output negative to earth.

I came across this article published by TDK-Lambda discussing grounding of open frame power supplies that may be relevant, though it does not answer the question: https://blog.uk.tdk-lambda.com/uk/2015/06/16/grounding-open-frame-power-supplies/

Would love to hear from somebody with more experience in the electrical world.

Edit:

To add to the discussion, the datasheet for the 12V power supply from TDK-Lambda mentions that Ground MUST be connected (See note 4). Again, no idea why Taito ignores this requirement, as it seems totally illogical to not follow this direction: