Ungrounded power supply.How dangerous?

Never run without ground

This will either kill you or what is infinitely worse - fry your laptops innards.

Please dont run it without the ground conn. Make sure you get this issue fixed first thing and then enjoy using it.

Cheers

reminds me of the simpsons episode where homer couldnt get the plug into the wall because one of the prongs was bigger than the other, so he sanded it down ;-)

Or when that idiot in "Just married" couldn't get the thing into the european outlet. Hehehe...

The simpsons, what a good show.

Cheers.

That was funny!!!

ive also heard of people getting mild electrical shocks from their laptops because their ground was faulty. Those would probably be amplified if you bypassed the ground alltogether ;-)

I've heard a 10 volt capacitor could melt a screwdriver tip touched across the leads. Hope that doesn't happen!

I was actually getting small static discharge from my lappy a few weeks back (it's in the shop right now....getting some minor probs looked at). I figured it was from the lack of humidity around here lately (Virginia Beach). I took it with me down to Puerto Rico for a week and a half and didn't have any static shocks then.

Boy, none of you must be working in the sound industry. We cut the grounds off the plugs on almost everything we use, or use the 50 cent adapters that change a grounded plug into a hot-neutral only plug. The power supply would really have to be poorly designed to be able to get a shock off the computer with an open ground.

-- Daryl

> I've heard a 10 volt capacitor could melt a screwdriver tip touched across the leads. Hope that doesn't happen!

Capacitors are usually measured in microfarads, you'd need thousands of microfarads of capacitance to do that. I used to charge a 3000 microfarad, 150 volt capacitor off a wall plug with a diode and resistor in series, and blow small pits into coins to scare people. If I had a ground loop causing an audio problem I'd either cut off the ground lug or go to Home Depot and spend 50 for an adapter.

-- Daryl

Well,

Yes in most cases it is a bad idea to bypass the ground plug. The main reason many AC powered gadgets have a ground connection, is to prevent a shock when touching the metal or conductive housing. Obviously you cannot receive a shock touching plastic, except the voltage of a failing component is high enought it would cross through the plastic.

If you are running your notebook though a switching power supply, like most of them nowadays, the primary side (120V AC) and the secondary side (Notebook Voltage in DC) is galvanic seperated. This basically means that the power on the notebook side is potential free to ground. This is one reason there are transformers made, so when you touch one lead on the secondary side you do not get shocked. If you would hold both leads then you become the load of that curcuit and yes that hurts.

BTW, a 10V capacitor could melt/sauder a screw driver over the poles. If the capacitance is high it will retain a lot of current and is able to release that stored current very quickly, resulting in currents in 50A or more. In my appreticeship we used to charge 16V electrolyte C's to about 20V, crossed a screwdriver over the poles to let the sparks fly. Then we would ask the new guys to touch the leads after we would charge them again to 20V and they all would not do it. Then we touch the leads and the aweing started.

Sorry for the lenghty explaination...
Anosis

Yeah i've never heard of anyone being shocked by a laptop, kinda funny. I run stuff all the time w/o it being grounded, and i've never had a problem with it, heck my old compaq laptop power cord doesnt even have a ground. I dont see why it should be a problem at all,

about the caps, had soem good fun making a coil gun with a lot of magnet wire and some nice 1farad capacitors....

Problem with ungrounded power supplies..

The problem you have with running the power supply ungrounded is INDUCTANCE.. That 6ft power cord connecting your power supply to the outlet can induce a voltage of ~45Vrms While this voltage isn't enough to cause much physical pain it can damage electrical devices. Also if you are running the power supply on an outlet that is in Europe ie 220V the induced voltage rises and can reach 80-90V.. this is more than enough to cause pain.

A solution of course is to disconnect the ground not at the outlet but at the power supply. By doing this you eliminate the induced voltage on the ground. I would suggest though that you not bypass a ground.

Instead install an isolation resistor on the ground line of the interface where you are getting the ground loop. Installing a 1/8 watt 100 Ohm resistor on the ground line of the usb device should eliminate the hum.

A couple weeks ago a forumn member in Singapore was getting shocks from his laptop because he had bypassed the ground. It is not only dangerous for you but also for your laptop.

For more information on ground loops you might read thisarticle.

> The problem you have with running the power supply ungrounded is INDUCTANCE.. That 6ft power cord connecting your power supply to the outlet can induce a voltage of ~45Vrms

This is great! Then with a 16 foot cord I can get 120 VAC and can run my refrigerator on it. Where do you get this stuff?

- Daryl