is this OK grounded ? os miss wiring connection?.. Thanks(picture)

this is a 2 chassis preamp, power supply & preamp connected via 4 wires umbilical cord using Lumberg LV thread locking connectors.

Few days back troubleshooting a problem (not solved yet) , found this. The yellow wires (ground) on both chassis board end on connectors where gone to no wires, and on the umbilical cord is are a black wire that happen the same (to nowhere) but on opposite pin. Could be a miss from the builder ? None has continuity to chassis or AC ground outlet.

If YES how it works good for years ? 😕
 

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Excuse me,
there are 4 wires on both side,
one wire on each side is not connected to the other side,

so there are 3 wires used to connect to the other side,
+V (plus), -V (minus), 0v (ground.) ?

Its a power supply in a metal case. (Shielded by metal)

First I want to know if I were right.
could it be 3 wires are enough.
 
Johnmath, thanks . This is an H2O Audio (designed of S250 amp, for low impedance Apogee full ribbons speakers) and this the Fire preamp (2010-2020)?, to emphasized the S250 amp, this one was builded around 2018?. Unfortunately the designer Henry Ho past away this year and are no circuit recorded.
6moons audio reviews: H2O S250 Signature & Fire

Alerxchoi- yeah are 4 wires but 1 is low voltage (12v) for led and... ? thanks too
 
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Olddiy, so probably PS & preamp run as 2 separate circuits ?
even that, I ask me where the ground is hooked on them ? I do not find no where. or if not necessary ?.
I talk on my ignorance, I love audio but how works learning each day . thanks all
 
What I missing, is that ground on both units running through 39,0000 50v caps that are not grounded to chassis or ac plug and umbilical snake has a black clown wire that go nowhere too.

pictures of both

more about units: https://6moons.com/audioreviews/h2o2/1.html[/url]
 

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I couldn't access above web

I can access the following web

6moons audio reviews: H2O S250 Signature & Fire

in the web I saw a version2 of your preamp,
there they use one attenuator in order to use remote , yours use 2 very high grade attenuators.

In one of the photos all 4 wires are used inside the preamp and power supply,

I am expecting someone to solve this missing wire connection puzzle.

May be a schematic might help.
 
How foolish I am to stuck in such a case with no data about its design.

Is the preamp working fine?
if its fine then the wiring is done in purpose by the designer.

the preamp might only need a single power supply other than the 12v for LED.
 
Thanks Alexchoi,
it worked fine but recently start an issue on one channel, but today found that a toroidal trans was the fault. So ordered.
What no make sense is the board has the wire output ground connection and builder take care to solder those cables (power supply yellow from board, preamp yellow from board & black wire on the umbilical cord on opposite location).
And due from one chassis to to the other the connectors has inverted installation that could cause the confusion by the builder (my speculation only).

The preamp on the 6moon interview was the 1st version and due remote issues some changes came in. mine was an client order with some changes.