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I'm an electronic technician so I have a little experienece with power supplies, etc, but electronic keyboards is NOT my strong point. My A-33 appears to be destroying power supplies as soon as I plug them in. No smoke, smell etc, they just stop putting out 9V DC (center tap)when measured w/my meter. Any ideas, particular what resistance should I be seeing at Rolands' input with the A-33's power switch on and off. No power supply plugged in during measurements, of course. Thanks! Tom Adams

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If you know what the normal amperage is during use,you can obviously figure it out using the volt,current,resistance,formula.If you do not know the normal amperage,I think power supplies are rated to be used at about 50%(I am sure they are not made to run at 100% for the long times necessary),so if the output is listed on the power supply,that is a reference(with the power supply output,you probably know the rate,percentage better than I do).If you are not 100% sure about the stuff I suggested,I would call the maker and see what they are willing to tell you at least.Just giving you an outside the box perspective.Good luck and let me know how you make out!

Posted on Aug 05, 2010

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But first check the warranty of your unit if it is already void.If not avail it, the manufacturer will fix it for free and/or little charge only...

Please rate my help,

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As you will know, it will be a switched mode supply, therefore dangerous to test in open circuit state.. Be carefull! - As a technician, you will know that you can check some obvious test points, for example the diode bridge and somewhere near the output, where you might expect correct DV volts. A 'CRO' might be handy here as well, but a digital Volt/Ohm meter is OK too.

Try these sites for help:

http://www.daileyint.com/hmdpc/manual.htm

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Remember: Beware of dangerous voltages in switched mode power supplies. They can bite! It may be better to replace the unit.

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There are a number of issues that could cause this, the most likely culprit is the power supply, when I say power supply I mean the internal power supply, 
This means that you have already obtained a good "known to work" AC to DC power supply, and tested it on your keyboard to see if that is the problem. 
If you have completed this step, then your next step is to test your unit with batteries only, if the keyboard works, then you know your problem, is internal to the keyboard. 
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 (a note here for those who have no experience working with internal electronics)
If you have no experience working with internal electronics I would not recommend, opening your keyboard. 
Two reasons, one, will void warranty if it still is under warranty. 
secondly, you could accidently cause more damage to the unit. 
Now if you are still reading, and feeling confident, you know that as a child you have dissembled many many electronic devices, just to see how they work. 
If you do decide to open the box, disconnect the power supply to the unit including any batteries. 
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The second and more challenging issue will be the internal power supply to the keyboard, or the interface that connects to your ac to dc converter. 
This can be much more trickier, and I wont go into it here. 
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If you examine the boards, (electronic circuit boards,) and notice burned, connections, (darker than other circuits) then most likely it will not be worth trying to fix. 
Hope this helps somewhat, if nothing else, take this print out to your local service dealer, and that will help in getting your keyboard repaired, 
Delete this part, before taking this to your dealer, 
Most electronic products can be easily fixed with a power switch, or power supply, however, many dealers will not tell you this and give you an estimate of fixing the unit that far exceeds the actual cost of repair, 
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