Burning smell from power supply

demogo

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Hi,

I just put in a new power supply in my Gauntlet Legends.

It's a 200w supply with the funky molex connectors that my GL needs.

Anyway, it seems to work but I'm defniitely smelling a burning smell with it on and it's worse with the game powered up.

Is this normal for a brand-new power supply? Something burning off? Should I be alarmed?
 
That is definitely not normal. I would contact the vender that sold you the PS and get them to drop ship you a new one.

I have had one like that and several hours into using it there was a loud pop and the power went out. It turned out that a cap had exploded (key word: exploded). I replaced the cap and it functioned correctly until recently when the voltage regulator blew and fried the motherboard it was connected to. Needless to say it went in the trash immediately. In retrospect, I should have just called the vendor and sent it back for replacement. I'm four chips into rebuilding the motherboard and it is still not 100% :(

ken
 
The manufacturer said that it was likely lacquer on the transformer.

I assume it will burn off at some point soon but asked just to make sure. :)
 
OK

If that's true then plug it in without anything hooked up and leave it on for a bit under supervision. If it stops you're ok and you haven't just fried your game board.
 
That is true; it is common for new devices like a power supply to give off odder.
They do dissipate tons of heat so heating the lacquer with resulting vapors sounds valid.
I wouldnt say lacquer on the transformer by itself, likely all the new components that may have some sort of dressing inherent in manufacturing.
 
There's a big difference between a burning smell and a hot lacquer smell. The hot lacquer smell is indeed common on brand new power supplies, and will persist for the first couple days. An actual burning or ozone smell is NOT normal, however.

-Ian
 
If that's true then plug it in without anything hooked up and leave it on for a bit under supervision. If it stops you're ok and you haven't just fried your game board.

NONONONONONO!!!

Switching power supplies require a minimum load to operate and can self destruct if not loaded properly.
 
Out of curriosity, How?

There is typically a label on the supply or manufacturer's specs somewhere giving the load current ratings and mention minimum load. Use power resistors to derive this load current. Make sure to size them properly for wattage or you'll get a whole new burning smell from the resistors.

For example - if a 12V supply has a minimum of 100mA, you will need a load resistor of 120 ohms. This resistor will be dissipating (as heat) 12V x 0.1A = 1.2Watts. In theory, you could use a 2W resistor - but that would get hot enough to burn your fingers pretty badly. I would go with a MUCH larger resistor such as a 10W.

Ed
 
Gotcha. Can also fill that power variable for say a 45W light bulb to see what amps are drawn with what power to know if it will be virtually seen as a short.

P = I*V = I^2*R

Where:

P = Power
I = Current
V = Voltage
R = Resistance

So without a load the energy drawn by the unit must be dissipated in heat melting the unit down?

I thought it wouldn't draw anything at all without a load, but if that was the case, how would you know it was working or not for the so called 'bench test'. Could it be the minimum required load it a matter of unit efficiency and that the minimum is a low end benchmark for acceptible / reliable operation?

I love a good technical moment! :)
 
So without a load the energy drawn by the unit must be dissipated in heat melting the unit down?

I thought it wouldn't draw anything at all without a load, but if that was the case, how would you know it was working or not for the so called 'bench test'. Could it be the minimum required load it a matter of unit efficiency and that the minimum is a low end benchmark for acceptible / reliable operation?

I love a good technical moment! :)

It depends on the exact power supply you are testing. Some switching supplies have an internal load of some type in order to monitor itself.
The old (usually really old) switchers could sometimes be damaged (toastification) without min load.
Most will actually work fine without the minimum load but won't guarantee the voltages to be within spec. Some of them actually have the minimum load built into the power supply such that the user doesn't need to worry about minimum load.
 
I typically use a car taillight bulb as a load. I put it on the 5v rail (the one that usually wants a load). For computer power supplies, I just use an old hard drive set to spin up automatically.

-Ian
 
For what it's worth, the burning smell seems to have fallen off a great deal as the manufacturer told me it would...

Voltages its putting out seem fine.
 
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