Power Supply for Juno DI


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Is it OK to use a power supply with the same polarity and voltage but with a lower amp rating?

I replaced the factory
Roland PSB-1U (9V, Negative tip, 2a ) with a
Radio Shack adaptor ((9V, Negative tip, 800ma).

It seems to work fine.

Could this lower amp Adapter cause damage to the keyboard?

Thank you
 
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I would only ever use a genuine adaptor in any device.

Our Radio Shack trades under a different name but the quality of their devices is questionable.

With your adaptor being of lower rating than Rolands own if your DS requires current approaching the rating of your adaptor then saturation can occur and this would probably result in an instability of the output.

There is more to a good power supply than a transformer, a bridge, a couple each of a zener and a capacitor which is all that is needed to produce one at its basic level.
 

happyrat1

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First off, not all power supplies are created equally. There's more to it than just current and voltage. Keyboards are computers and they expect REGULATED supplies. Furthermore most modern computing devices use switched mode regulation.

That being said, current and voltage still do play a critical part.

Stepping down the current by half definitely can damage computer hardware. You may not have encountered it yet, but imagine a stress test where all notes are playing at once while the rhythm section is also playing full blast. At that point starving the circuit of current can have some serious negative effects.

I agree with Biggles on this one. Stick with the original factory supply.

Gary ;)
 
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I have just looked at the one and only Roland power supply that I have, it feeds my Boss GT100 guitar pedal unit, its 9v and 2.0A but it is the 1U so way smaller than the Juno's 7U which is 9V and 4.0A.

The Op is very lucky that his Radio Shack psu has not fried itself and his Juno already.

In the UK the 7U is £34, my GT100 was an Ex demo unit and I had to buy one for the 1U which cost me £25
 

happyrat1

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Thanks to everyone for the expert advice. I ordered "KFD 9V AC Adapter Power Charger. ".
Same Voltage, polarity and amps as the original

Regards
 

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