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Who can explain wallwart power supply spec ?

Disclaimer: I know this may not belong in this part of the forum but I'm not sure where else to put it.

Okay so here's the scoop. I recently bought a compressor on eBay. The add said that it came with a "brand new universal power supply". So when I receive the item I right away noticed the wall-wart was the wrong mA for the unit. So I ordered the right one. When I got the right supply the unit worked fine for about two to three hours... then it crapped out on me and produced a light hiss. Now what I'm doing is trying to explain to the guy I bought this from why a supply with the wrong mA is harmful to a unit. Im not extremely technical savvy so I can't explain it beyond the point of "well if you use the wrong mA it'll fry the damn thing". So I was hoping someone could give me a good answer that will help explain this to a man with a rocks for brains.

By the way the supply was set to 600mA and the unit requires 1000mA. Which from what I know its worse to under power something.


Pro Audio Guest Tue, 01/23/2007 - 12:20
The mA's mean the electrical current you are giving to your equipment, it means the quantity of electrons are flowing througt the circuitery.Its dificult to say if it worse to give it less or more current, cuz every equipment has its own treshold up and down so maybe its worst to have 1100mA than 600mA may not. Also, most of the equipment i have bought from brands like digitech, zoom, an boss, (at least the effect procesors) only work with the original power supply. Im sure its not enough information , but ill try research more about it.


Kev Tue, 01/23/2007 - 14:00
the power supply doesn't push electrons to the equipment

the equipment is the load
the load will draw current

the power supply has an ability to provide current ... whether it is needed or not

the equipment may be rated ... max current draw 500mA
... or it might be rated as ... max power usage 5 watt

if this unit is a 10 volt unit then we are back to a max current of 500 mA


It is good practice to have a power supply with a current ability greater than the load requires

generaly a draw of 60% leaves good headroom

I see nothing wrong with using a 1000mA power supply for a unit that will draw 500mA
it should run cooler

The Voltage must remain the same
AC or DC must also be adhered to

Pro Audio Guest Tue, 01/23/2007 - 14:10
Re: Who here is savvy enough to explain this?

Just to try to clarify this. The compressor actually required 1000mA... but the guy who sold it to you only included a 600mA supply? (That is a bit underpowered in my opinion as a person trained in electrical engineering). I mean 900mA or even like you could have maybe gotten away with with no ill effects.. but 600 was way too low.

I dont know if your wall wart was AC to AC or AC to DC, but did you check to make sure you got the proper polarity one. The polarity as you know is indicated by the little symbol on the unit and the accomanying text on the wall wart.

When you replaced it... Did you replace it exactly with a 1000mA unit or did you overrate it a bit. What was the exact value of the replacement? Right polarity?

My opinion is that your kind of screwed. You may have gotten a "lemon", and its hard to pin that on the seller.

If the thing was working for 2 - 3 hours when you received it.... you have to really ask yourself if it was really "broken" to begin with... so can you really blame the seller. It broke in your custody, while you were using it. I dont know why it crapped out on you, and I feel sorry you got screwed... but your in for a heck of a battle trying to get a refund on this one. Thats the part if really feel sorry about...

I mean you can give the guy a bad feedback.... but that may be the extent of what you can do in this situation. How much did you pay for the unit by the way?