A Strange Problem with a Desktop PC and an Inverter

[sdowney717]

I modified a case for a PC and made a built in PC that fits under the chart table.
I have a MSW invertor that runs everything just fine and USED to run the PC.

But now every time the PC is plugged into invertor power, the invertor shuts down its output. I verified the PC runs fine on shore marina power. And I verified the invertor starts flourescent lights, runs power tools, runs the fridge, runs the microwave, runs everything I plug into it.
I notice now when I plug in the PC power supply, I get a large zapping and LOUD sounding spark which I dont recall seeing before. And reading the manual for inverter it says if the load exceeds the rating the invertor shuts down the output. Invertor is 3000 watt, 6000 watt peak.

So is the PC power supply doing something strange?
Like a short which is there for a moment everytime it is plugged in?

Seriously, the PC is working perfect on shore power.
When plugging into shore power, the PC fans momentarily start and I dont hear the same spark. Then power on and it boots up fine.

Do they make a 12 volt PC power supply?

[Adamante]

Originally Posted by sdowney717

I modified a case for a PC and made a built in PC that fits under the chart table.
I have a MSW invertor that runs everything just fine and USED to run the PC.

So are you saying the the inverter used to run the PC until you made the PC case modification?

[sdowney717]

I made the PC mods and it worked afterwards but now wont work.
SO, I dont understand except maybe something odd happened to the power supply.

[Adamante]

Originally Posted by sdowney717

SO, I dont understand except maybe something odd happened to the power supply.

I think you are on the right track. I would get a new $20 power supply and give it shot. You need to carry a replacement PS anyway.

I notice now when I plug in the PC power supply, I get a large zapping and LOUD sounding spark which I dont recall seeing before.

Can you tell if the zapping is coming from the inverter or the PC power supply?

[sdowney717]

the zapping comes at the plug when I plug it in. I wonder if the PS has a large momentary short. Weirdly I do not get the same zapp when I plug into the shore power. And I verified the receptacle works fine and it is brand new.

It makes a loud zap with a visible spark and then the inverter turns off.

I could try one more test and that is plug the PC directly into the back of the inverter.

IF for some reason, I can never make the PC work again with the inverter, I think a UPS power supply could act as a buffer between inverter and the PC.

Do you think the PS has a ground fault and the inverter senses this?
I also wired a GFI outlet but plugging PC into GFI versus non GFI gets same result, but if inverter is GFI then it makes a little sense, but I did not think it did have GFI.

The shore power cord is not GFI.

My power from inverter runs thru an on-off- on DPDT switch, (switches hot and neutral together) one side is inverter, other shore-gen. The output either shore or inverter runs first into a single receptacle then on to a GFI which feeds all the other outlets on the boat.

I kept one outlet as non GFI for the fridge

[sdowney717]

Ok, tried a different PS and it works fine with the inverter.
So that PS has issues

[nigelmercier]

Originally Posted by sdowney717

Ok, tried a different PS and it works fine with the inverter. So that PS has issues

Is the inverter a Sine Wave, or Modified Sine Wave? If MSW, then it could cause the PSU to malfunction.

[amytom]

I would also check the Hot vs Neutral wiring, maybe they are swapped between the inverter relay and the PC power supply. Some PSU's may ground the neutral leg. (only on older equipment though).

[sdowney717]

it is a MSW inverter. These PS are all fairly old. This one from a Compaq is much heavier and bigger, has 2 transformers inside, other one does not, so might be better.

[Adamante]

Originally Posted by sdowney717

Ok, tried a different PS and it works fine with the inverter.

Cool!