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sparks and smoke in my midi / usb !!
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matt thomas
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#1
20th May 2006
Old 20th May 2006
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sparks and smoke in my midi / usb !! emagic amt8 users please read!

hi

I just plugged in my emagic amt8 for the first time (midi 8x8 interface via usb)

I bought it second hand with no adapter.

I bought a 9 volt AC adapter as I am told it takes. (ie. AC in AC out)

I plugged it in and usb'd it to my G5 and it all showed up in the audio/midi set up nicely.

then I started smelling a burning plastic smell, and I soon noticed smoke coming from the unit.

so I unplugged it quickly.

I took the lid off but the burning had died away (it was about 10 mins later) so I couldn't tell where it was coming from. So I plugged it back into the 9v adapter but not my G5 and waited for smoke. Nothing happened.

So after a while I decided to plug it back into my computer but as I did so sparks arced between the usb connetion and the usb cable. No need to say I deided not to plug it in properly.

Does anyone have any idea whats causing this or what I can do, preferably not throw it away..

I have it plugged in via a powered usb hub.

thanks
narco
matt thomas
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#2
21st May 2006
Old 21st May 2006
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actually, it isn't plugged in via the hub, but it is plugged in via a usb extension cable

narco
#3
21st May 2006
Old 21st May 2006
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Are you sure that was the right power supply? Sounds kinda weird. Was the unit new? I mean I know it wasn't new new, but had it been used before?
matt thomas
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21st May 2006
Old 21st May 2006
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After opening it I have found there is a resistor just by the psu input that is fried, there are two of the same resistors right beside each other, I am wondering whether a previous owner put in a DC adapter instead of an AC..

I tried to take a photo with my phone to post but it is too small for my crappy fone camera.

the person I bought it off just emailed me and said that it wasn't compatible with his G5, and besides that it seemed to be fine. Although I am pretty sure it is G5 compatible, especially as it showed up in my audio/midi setup

narco
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21st May 2006
Old 21st May 2006
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Maybe check the polarity of your 9v power supply against that of the amt8.

Sparks out of a USB cable! Yikes!
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jbo
#6
21st May 2006
Old 21st May 2006
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isn't emagic owned by apple? i'd be pretty suprised if it wasn't compatible.
matt thomas
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#7
21st May 2006
Old 21st May 2006
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Quote:
Originally Posted by jmiller
Maybe check the polarity of your 9v power supply against that of the amt8.

Sparks out of a USB cable! Yikes!
AC doesn't have polarity does it?

narco
#8
21st May 2006
Old 21st May 2006
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Quote:
Originally Posted by narco
AC doesn't have polarity does it?

narco
If you look at the plug where the ac adaptor plugs in, there should be a diagram showing whether the center is plus or minus. Those universal adaptors from Radio Shack can be reversed for just this reason.

You know how one prong of an AC plug sometimes is larger than the other prong, like on a TV cord? That's to keep the polarity correct.

But I don't know about reversed polarity frying the thing, although I suppose anything's possible.
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21st May 2006
Old 21st May 2006
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From what I know, usb delivers its own power supply. Haven't had wide experience but try without the AC adapter.
matt thomas
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22nd May 2006
Old 22nd May 2006
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Quote:
Originally Posted by max cooper
If you look at the plug where the ac adaptor plugs in, there should be a diagram showing whether the center is plus or minus. Those universal adaptors from Radio Shack can be reversed for just this reason.

You know how one prong of an AC plug sometimes is larger than the other prong, like on a TV cord? That's to keep the polarity correct.

But I don't know about reversed polarity frying the thing, although I suppose anything's possible.

But isn't this just for DC? I mean AC is continually changing polarity 50 or 60 times a second isn't it?

the adapter (9 volts AC) says nothing about polarity

This unit needs power aside from the usb bus.

narco
matt thomas
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22nd May 2006
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I just edited my original post. the adaper is AC in AC out..

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#12
22nd May 2006
Old 22nd May 2006
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IIRC, polarity with regard to alternating current is important in the case of devices that are grounded internally.

(This might be going over my head, so check with someone who knows more than me before you use this information in ways that might put your life in danger!)

When you have a polarized outlet, one slot should be connected to the ground. Some electrical products take the ground from that slot and attach it to the case of the item in question. Obviously, you wouldn't want to get the polarity reversed in such a case.

AFAIK, if you plug something like a TV in backwards, you can fry it. Same deal if your electrician got the convention reversed.

In the case of a device that runs on a low voltage power supply, I don't know if reversing the polairty could fry the device, but I'd say that wiring the case hot isn't good.

I say go out for beer.
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22nd May 2006
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mmmm.. beer...

narco
#14
22nd May 2006
Old 22nd May 2006
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Just thinkin' aloud.

Are you sure you are using a proper adapter? I owned the AMT8 many years ago but it's been awhile. I thought it used a DC adaptor, but it's been years.

Quote:
Originally Posted by jbo
isn't emagic owned by apple? i'd be pretty suprised if it wasn't compatible.
Emagic was not owned by apple when the AMT8 was designed.
matt thomas
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22nd May 2006
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I was wondering that myself, can anyone confirm?

I go the info from this thread..

Emagic AMT 8 users?

quote:

"Hi Narco,

Just checked my AMT8

The PSU output is AC 9V - 900mA.
Model No for PSU is AD4120-09-900 - Brand is "UL"

Good luck.

Cheers
Dave"


narco
#16
22nd May 2006
Old 22nd May 2006
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Quote:
Originally Posted by ketz
From what I know, usb delivers its own power supply. Haven't had wide experience but try without the AC adapter.
It won't work- the AMT requires power.

JR
MDM
#17
22nd May 2006
Old 22nd May 2006
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hey i also own the AMT8 with a G5 - works GREAT - best midi interface ...

Comes with an AC adpater of 9 volts, 0.9A and it says UNITOR8 on it
matt thomas
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22nd May 2006
Old 22nd May 2006
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Is the output AC or DC? (as opposed to the input)

If its AC it'll PROBABLY have a little picture of a sine wave beside it

If it is DC it'll PROBABLY have a dotted line over a solid line and/or a diagram showing whether the tip or ring is postive or negative.

thanks

narco
matt thomas
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22nd May 2006
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anyone?

I've searched heaps on the net and found a few people asking the same question but no answer, except for this from a logic user group:

Re: AMT8 question
... I don't think so. The original power supply provides 9V AC. As the AMT8 has a AC/DC converter built-in, it does not matter if you connect AC or DC. ... ...



But as I only found this once on the whole web, so I was wondering if someone could tell me what their power supply says.

AC or DC output?

thanks

narco
#20
8th March 2012
Old 8th March 2012
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Hi Narco,

I'm in a similar situation actually...I'm afraid to try a 9V DC after reading this post.

Did you manage to figure out what kind of adapter it requires exactly?

I too was under the assumption that with an AC (out) adapter polarity is irrelevant...
#21
25th October 2012
Old 25th October 2012
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For the guys in the USA, I have an image of the original power adaptor supplied with the Emagic AMT8. Remember the Amperage spec is the minimum and ahigher amperage can be used without problem. That means if you have a an adapter with a higher Amperage eg 1A, 1.2A etc then this will fine, so long as the the other details are correct, ie: Input voltage the same as your country, USA 120V, for the rest of the normal civilised world 230-240V. If the input Voltage is 9V then this must be adhere to.

Image of USA AMT8 power adaptor:

Quote
1
matt thomas
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#22
14th November 2012
Old 14th November 2012
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I just saw this thread had been resurrected.

I took the AMT-8 in to be repaired and they fixed it and told me that the PSU needed the earth lifted, so I have been using it fine for years now via an adapter plug that lifts the earth.

matt
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