EMU Classic Keys power supply problem

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EMU Classic Keys power supply problem

Postby Viktor2000 » Sun Oct 14, 2018 3:18 pm

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1) Hi, does anyone has a picture of an original power supply for EMU Classic keys?
I find it strange that on the back where you plug the power supply it says 9 V AC, the power supply converts the power into DC I think?
2) Does anyone knows what polarity is the center pin? Some of the adapters I know has NEGATIVE (-) center pin.
3) If you make mistake with the polarity would the equipment break down?
Thanks in advance.
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Re: EMU Classic Keys power supply problem

Postby Mooger5 » Sun Oct 14, 2018 4:06 pm

The power adapter for that unit must be output AC, not DC. The rectifying bridge, smoothing caps and regulators are already inside the unit. Since it´s AC, there is no positive nor negative. This prevents from plugging in the wrong polarity.

Whenever I buy units like that without a power adapter, I just use a common DC adapter and remove everything leaving only the transformer inside. EDIT - By "common" I mean LINEAR power. The above doesn´t work with modern switching power supplies. But you might want to buy a new power adaptor. Look for exactly what it says: 9VAC output. Keep in mind the current rating: You can use any adaptor prepared for the specified current consumption or higher, but never lower.
Last edited by Mooger5 on Sun Oct 14, 2018 4:23 pm, edited 1 time in total.
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Re: EMU Classic Keys power supply problem

Postby Mooger5 » Sun Oct 14, 2018 4:20 pm

BTW the current rating seems to be 1000mA. So, 9V AC, 1000 mA. Those are easy to find. Good luck.
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Re: EMU Classic Keys power supply problem

Postby Rasputin » Sun Oct 14, 2018 6:43 pm

While that power adapter isn't particularly rare, most things use DC so 9VAC is trickier to find just by rummaging through your closet. If you get stuck:

I don't know about aftermarket versions (although some may be worth looking into), but the original NES game system uses a power adapter with the correct specs. The model number for the adapter is NES-002.

The Johnson J-Station and Line 6 POD (original "bean" version) as well as the early Line 6 modellers use similar power supplies too, if you happen to have those around.
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Re: EMU Classic Keys power supply problem

Postby Viktor2000 » Sun Oct 14, 2018 8:36 pm

Thanks a lot for the advice Mooger5.
Greetings.
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Re: EMU Classic Keys power supply problem

Postby Viktor2000 » Sun Oct 14, 2018 8:38 pm

Thanks to you Rasputin as well.
Greetings.
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Re: EMU Classic Keys power supply problem

Postby Mooger5 » Mon Oct 15, 2018 1:08 pm

Rasputin wrote:I don't know about aftermarket versions (although some may be worth looking into), but the original NES game system uses a power adapter with the correct specs. The model number for the adapter is NES-002.


Any generic adapter will do, Rasputin, as it´s only a power transformer. Some may be fused but there should be enough protection inside the unit.

Just googling "9v ac/ac 1a" and paying attention to the country´s mains voltage and plug type gives plenty of good results.
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Re: EMU Classic Keys power supply problem

Postby Rasputin » Tue Oct 16, 2018 2:21 am

Mooger5 wrote:Any generic adapter will do, Rasputin, as it´s only a power transformer. Some may be fused but there should be enough protection inside the unit.

Just googling "9v ac/ac 1a" and paying attention to the country´s mains voltage and plug type gives plenty of good results.


Sure. As I said, they're not rare or esoteric at all. But you know when someone has a shoebox full of old answering machine adapters and the like? Not going to find one in there, probably. I was trying to list things a musician might already have at home.
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Re: EMU Classic Keys power supply problem

Postby Mooger5 » Tue Oct 16, 2018 7:07 pm

I see. Well the 12 VAC are more common, I think. I power my SE50 with an adapter that belonged to a Soundblaster speaker system. And my SX700 with an adapter originally made for halogen lamps. Now, I didn´t look at the unit´s Schematic but it probably uses 78XX and 79XX regs. Those can stand up to 35VDC, so 12VAC are still OK. The only problem is higher working temperature, so better not recommend this if you don´t know what the unit uses for heatsinks.
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