Yamaha keyboard dead power

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Elliotmarvelous

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Hello, I use a yamaha e433 keyboard which was working perfectly. There was a day the power supply to my home was very low such that it can't even charge a mobile, so my cousin connected wire to the keyboard battery section directly to light without adapter. He said the keyboard flickered for seconds then went dead. Now when connected through adapter to light it just make a hum and does not power on. Same thing with batteries. The keyboard has a fuse on the power board, could it be blown , or the whole power board..please help
 
As it is designed to work with an adapter it is unlikely to have a power board. It is very unlikely that the fuse (If there is one.) would protect it from such sever over voltage. (110 or 240 volts AC when it was designed for something like 12 DC.) I think so much damage will have been done to make it not worth repairing.

Les.
 
My Yamaha electric Piano has inbuilt regulator, but yours may not. Most likely a simple fix after you find the blown fuse or diodes etc when the Line restored with overvoltage. Or the case with a brown out drawing excessive current and overheating. A line filter and MOV Can protect some of overvoltage these events but not the low V. But low V is a sign of poor power infrastructure in your region, so you must have more protection. Check the Vdc with a DMM ($7) or insert to socket Vac . It should be +/-10% but maybe not where you live
 

I suspect you haven't read what happened correctly? - they put full mains directly on to the battery terminals.
 
while it's possible only a regulator is shorted, from the sounds of the symptoms, the keyboard probably has fried amplifiers that drive the speakers. when you apply 10 or more times the voltage that an item runs on (even worse AC at that voltage), that high voltage basically goes wherever it can. with the treatment it was given, i doubt Yamaha would fix it under warranty. you had a unit that used low voltage DC for operation, and you fed it with high voltage AC. first, semiconductors tend to short when you apply reversed voltage to them (especially at a much higher voltage). on a scale of potential damage going from 1 to 10, applying full power line voltage to the battery terminals is about an 11.
 
If it dimmed AC lights you are lucky the components are Fire Retardant rated like FR4 but expect a pile of melted and scorched parts. I guess you are wiser now and your cousin is in debt. My brother did the same thing with a 5k$ CBC portable recorder in the early 70’s in the middle of Africa on 230V to a 120V rated unit. Poof.. no more “trip around the world” journal reports to the CBC.
 
 
unclejed613 said:
E=mc² (+/-1dB). Tag line
Click to expand...
.....................................................................................................
Funny ... yet Atomic reactions are the only things in the universe that are “ lossless for energy” and which losses are the “chief causes of all power tolerances in semiconductors and reactors” either process related or the results in bulk resistance, Rce or Rbe, Rs, RdsOn, ESR, DCR, ...thus tolerances are only due to our measurement accuracy.
 
I meant Atoms are completely lossless forms of energy, not the conservation of energy conversions.
 
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