Members Vito Corleone Posted December 13, 2014 Members Share Posted December 13, 2014 I figure some of you here can probably answer this? One of the keyboards I gig with is kind of a cheapy plastic thing with a wall wart power supply. The original wall-wart stopped working (the plug end started to short out) so I replaced it with a multi-voltage wall-wart from Radio Shack with the same amperage. It was working fine until the other night when it would power up the board but I had no audio output. In the process of checking things I thought maybe the voltage switch got moved. I remember from other experiences that lower voltage could sometimes result in keyboards powering up but not enough to send the audio signal. It was set properly to 9V, but just to see what would happen I bumped it up to 12V and the keyboard worked fine. Also this happened over two nights at two different venues. The first night I just didn't use that board for the gig. The next night, I had the same problem and that's when I switched the voltage, so it would seem that power from the venue is probably not the issue? What's most likely the issue here? Something inside the keyboard? Something inside the wall-wart? Impossible to tell just from a description? Link to comment Share on other sites More sharing options...
Members agedhorse Posted December 13, 2014 Members Share Posted December 13, 2014 Often, those inexpensive universal power supplies are underwhelming in their performance. What does your keyboard specify in terms of both voltage AND current? It may be that a 12v supply is correct, 9v sounds unusual for a small keyboard. If it's really 12v, I have a large quantity of high quality line lump supplies on my surplus shelf. Link to comment Share on other sites More sharing options...
Members Vito Corleone Posted December 13, 2014 Author Members Share Posted December 13, 2014 Often, those inexpensive universal power supplies are underwhelming in their performance. What does your keyboard specify in terms of both voltage AND current? It may be that a 12v supply is correct, 9v sounds unusual for a small keyboard. If it's really 12v, I have a large quantity of high quality line lump supplies on my surplus shelf. The original power supply was 9V/1200 mA. And it states 9V on the output jack. I see now though that the replacement I bought was only 1000 mA, so maybe that was the issue. Although it's worked fine for the last year or so. Link to comment Share on other sites More sharing options...
Members agedhorse Posted December 13, 2014 Members Share Posted December 13, 2014 Borderline fine... I would not expect a Radio Shack type part to have the same performance margins as the original part. Link to comment Share on other sites More sharing options...
Members Vito Corleone Posted December 13, 2014 Author Members Share Posted December 13, 2014 I think I can get the original part on Ebay. Probably best to just order up a couple of those. Link to comment Share on other sites More sharing options...
Members wesg Posted December 15, 2014 Members Share Posted December 15, 2014 You can't go wrong buying the OEM part, but I'm the kind of guy who will just order a compatible part from an electronics vendor, whenever I'm making my next order with them. I keep a factory brick in my gig bag, a separate brick in the practice hall, and a spare multi-voltage brick in my power cable bag that I plan to never use. It's my intention to gig with the brick from the practice hall, and to treat the OEM brick as a backup. Ordering them from a large vendor that I regularly do business with (Digikey, Mouser, Newark) helps amortize shipping cost, and gives me the opportunity to get the product in whatever form-factor works best for me...right angle connector, straight connector, off to one side, powerbar outlet blocker, lump in a cord, hideway prongs, etc. Here's a few from Digikey that you might like....make sure you get a part with the correct polarity and plug barrel size!. http://www.digikey.ca/product-detail/en/WSU090-1300-R/237-1452-ND/3094978. http://www.digikey.ca/product-detail/en/WSU090-1300/237-1451-ND/3094977. http://www.digikey.ca/product-detail/en/WSU090-2000/237-1425-ND/3094951. http://www.digikey.ca/product-detail/en/WSU090-2000-R/237-1426-ND/3094952. http://www.digikey.ca/product-detail/en/EPSA090130U-P5RP-EJ/T1188-P5RP-ND/2792484. http://www.digikey.ca/product-detail/en/EPSA090130U-P5P-EJ/T1060-P5P-ND/2235252. http://www.digikey.ca/product-detail/en/VEP24US09/1470-2336-ND/4488715. http://www.digikey.ca/product-detail/en/KTPS36-0940DT%203P/62-1170-ND/2708948...many more that might work for you The last time I opened up one of those multi-voltage dealies, it was an unregulated linear power supply, where the switch selected which secondary transformer tap was sent to the rectifier. I do not like unregulated power supplies, because the precise voltage that comes out of it depends on the input voltage, which can vary considerable in a stage environment. They are also more likely to cause 120Hz hum problems. I do not like linear power supplies because they are more expensive and heavier than switch mode power supplies. I also prefer buying universal (100-250VAC) supplies whenever possible. No good reason, just one less thing to worry about. BTW the first time I plug a power supply into a keyboard, I always check the polarity with a meter. Stuff happens. Wes Link to comment Share on other sites More sharing options...
Members maarkr Posted December 15, 2014 Members Share Posted December 15, 2014 yeah either buy the original or get a wart with the same voltage and HIGHer amperage. I have a bag of old PSs over the past 20 years and I can usually find something in there that powers about anything... if the line adapter fits the device. Link to comment Share on other sites More sharing options...
Members TimmyP Posted December 27, 2014 Members Share Posted December 27, 2014 The RS selectables are very poorly regulated. There's no telling what the actual voltage will be. Set it one notch low, and measure it when it's powering the keyboard. Link to comment Share on other sites More sharing options...
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