Fried my power adapter - will my substitute work?

[buzzer]

Hi,

Stupid me! I made a bone head mistake when I plugged my 110VAC wall wart adapter into 220V (I live in Thailand and have both 110 and 220 stuff). I have a very good 220 to 110 converter. But I didn't use it.

Would you believe it! he adapter is fried! Duh!

Here's the problem:

The burned out adapter (I'll call it #1) says 110VAC to 12VAC 1.5 A. with no mention of wattage.
The one I want to use as a replacement #2, says 110VAC to 12VAC 25 watts, with no mention of Amps.
Also when I put #2 on my multimeter it tests out around 14VAC instead of 12VAC.

So, as an amateur, I'm looking at 2 problems. While #1 says 12VAC 1.5 Amps, #2 says 12VAC 25 watts. I don't know enough electronic theory to determine if this is OK. Then. the second problem is the difference between the 12VAC specified and 14VAC actual readout.

My opinion is that the unit (an Axon AX 50 USB Guitar to Midi converter) will draw what it needs in terms of Amperage or Watts, and the necessary thing is to get the voltage right. But the reading of 14VAC on my multimeter bothers me a little. I've seen higher than specified voltages come out of many DC adapters, but was wondering, is this within an acceptable range for an AC/AC adapter?

Thinking it would be OK, I plugged a lower powered 110VAC/9VAC adaptor in for a second, and didn't get much response. When I plugged in the one I'd like to use into the proper voltage, then into the Axon it looked like everything was back to normal. It went through the normal startup routine, telling me the firmware version #, and proceeding to patch 001. However, though this made me happy that the adapter, and not the AX 50 was damaged, I shut it off, because I wanted a more expert opinion before I start actually using it normally.

Can I use the replacement without fear of burning out the Guitar to MIDI converter box it is powering?

Thanks,

Buzzer

[defaced]

Welcome to the forums. You're about ready to get a crash course in drooping power supplies and electrical power.

P (watts) = I (amps) * V (volts).
Your first power supply is 12V * 1.5A which is 18 watts.
Your second power supply is 25W / 12V =~ 2A

Because current is drawn from a power supply, and your new wall wart has greater current supplying ability than your first one, you're good to go on that front.

Now about the 14V on your new wall wart... Power supplies, because they have an internal resistance, will "droop" or "sag" when current is drawn from them. Your 14V reading is called the "open circuit voltage", basically it's the voltage without load. We don't usually care about it because very rarely are you interested in what happens when you're not pulling current from a supply. What we're interested in is the loaded voltage, which is the 12V on the wall wart. Assuming there is no form of active voltage regulation in your new supply (and I don't think there can be because it's AC), the way to read it's rating is "at 12V this can provide about 2A of current". If you use less current, the voltage will rise a little (approaching the open circuit voltage). If you use more current, the voltage will droop down a little bit. And if you pull too much current (like a short circuit), you'll burn the 12V winding on the transformer.

So... unless your new supply is very very stiff, and I doubt it is from the current rating, it should work fine with your box. A little over volting isn't going to hurt anything in this case.

[buzzer]

Thanks Mike,

You put it in terms I can understand. I joined this forum awhle ago, but that was my first post. It probably won't be my last, though, as I'm trying to put my home studio back together after several years of downtime.

So, you're imput is very much appreciated.

Thanks - Buzzer (Jeff)

[defaced]

No problem Jeff. I'm glad I could help.

As you probably already know, there's a wealth of information in the minds of the people who post here, so you'll be good to go when you put your studio back together.