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Author Topic: Negative voltage at AIC backlight?  (Read 2894 times)

Offline Rufus

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Re: Negative voltage at AIC backlight?
« Reply #60 on: December 23, 2013, 02:11:22 AM »
Ok...I think I've noodled something out about the Mean Well supply.  I went back and looked at the block diagram again, and it appears that while the G/G (COM, in the diagram) and mains earth may not be directly tied together they are internally shared somehow - with with a capacitor between the high side and mains earth presumably to create some delay/over voltage protection for given channels.  But it looks as if the circuit branches are self-draining at shut down, so nothing to worry about there.

I'm thinking though that I shouldn't ground my pit structure to/through the supply earth though, because a back EMF could harm the protective capacitors...but that I can use the wall plug ground over a separate cord with only the ground wire connected?  I'd lift this circuit with a relay at MAIN POWER - other than OFF, maybe with a slight delay.
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Offline Cupra

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Re: Negative voltage at AIC backlight?
« Reply #61 on: December 23, 2013, 02:17:28 AM »
Oops, that has gone under... or how ever you say  :harhar:

Yes, everything else is working without anny issues. Boards are dedected and at the power supply Pins of the boards the +12V DC is stable with the Switch on and it is 0,00 when the Switch is off.
The exact same circuit (a second one) is connectet to the backlight-connectors and there I have the -14V when i Switch off. But bowth funktions are working without problems or thermal abnormalities.
So for me I would say if eveything works proper there is no Need to do anything... I am just always a litte afraid if I have voltages I canīt explain  :notes: