<!-- from fixya rte -->How do i open case to repair power supply - Yamaha DGX630 - Digital Piano

dgx screws are so many..u have to open the speaker covers there are other screws inside...which u can only access by oppening the speaker back cover...you will also have to open the silver screws..all of the behind the cover..all this u r doing when you have separated it from the stand. place it on a mattress in need be to avoid accoustic wear.

Power failure?

First check the power supply / adaptor to ensure this is working correctly. Measure the voltage using a multimeter - if this is correct move on ( if not replace power supply )

Does the keyboard work if you hold the plug in the socket or move it slightly ? If so this is a common problem as the power socket on the pcb fails at the solder joint and will need to be repaired / replaced.

If this appears to be solid then you may have done some internal damage by either plugging in a power adaptor with a too high voltage or wrong polarity. If this is the case you may have blown some circuitry inside which controls voltage regulation.

Please report more if you have more information.

Hello,

Eurolive Active speakers from Behringer suffers of bad power supply/Amp design, if you open up the back of your speaker you will probably find that the AC connector has a burnt or loose connection as well as a black spot, if not, check the power supply/power amp coils for cracked connections, let me know for improve help.

Failure, likely in the power amp causing overloading of the power supply and dragging one power voltage into the range where the ripple voltage gets to the speaker. This is very ******* the speaker as it gets high DC current and can burn the voice coil. Slight chance that a filter capacitor has failed. In either case repair is needed.

That may be minor or very major. Open the unit and look for damage.

Best case, loose debris in the unit shorted something in the power supply. Probably replacing one or a few small components to repair.

Worst case, debris or failed component has burned large area of board. This would be fatal.

I have schematic so let me know what you find as source of the smoke. Note that most of these use surface mounted parts and require a bit of soldering skill to repair.

It would be helpful if you told us what type supply you connected to the unit.

These normally run off a 9 volt DC supply. Likely you wiped out the input regulator chip and maybe a diode and capacitor.

It is definetly worth repairing.

If you open it up the damaged parts MAY be obvious. There may be a couple which do not show the damage.

I have a PMP5000 that I had to resurect. I had to trace out the power supply to repair it.

I can give you hint: First, a small supply runs directely from the line and generates some of the small voltages. While this starts, the main power caps are charged through limiting resistors. The main switcher is brought online and if the power amps acheive balance, then a relay connects the speakers and shorts the limiting resistors.

This is what is in the 5000 and I suspect the 3000 is similar.

In my 5000, there was arcing at one side of the power amps. The board was burned and three power fets fried. Cancer of burned board had to be carved out and traces replaced by hardwiring.
In addition, the limiting resistors were blown open, both main switching transistors were blown and 4 small driver transistors (surface mounted) and several diodes AND a switching regulator chip (surface mounted).all fried/

Hint: When restarting the unit, put a 150 watt light in series with one of side of the power input to limit the current in case you did not get all the dead bodies out.

This is a class "D" amp which drives PCM waves into a filter which is then the audio output. It is much more efficient thaan a linear amp.

This needs to go to the repair shop. The protect mode is turned on when either the power supply has a problem or one or both power amplifiers have a problem. These are often blown components.

These units are HARD to work on. To open you have to first remove then front panel before you can remove the back panel that has the power supply and power amps/heat sinks.

Compare repairs of these units to working under an automobile dashboard!

Hint: On startup, use a series 150 wat lamp to limit current while repairing. SInce these use a switching supply operating off the input line, use an isolation transformer for personal safety.

If you feel comfortable doing it you could try removing the back and examining the power supply. Make sure the power cord is not plugged in. Remove the screws holding the back on the organ. Look to see where the power supply is. It will be a fair sized metal box that the power cord comes out of. Look for a fuse holder on the box.If there isn't one or you already checked the fuse look to see how the power supply is fastened down. If you can remove it you can check the power cord from the plug end to the connection in the power supply with a volt ohm meter on the lower resistance scale. Check both sides of the power cord . Look for an internal fuse soldered into the circuit if there is one. Check it also. You can also check the power switch the same way. Think of the power cord and switch etc as a garden hose. You want to make sure that the flow of electricity is not interrupted any where between the plug and the power transformer. Do all these tests with the cord unplugged. Also avoid touching anything connected to the filter capacitors as they store dangerous amounts of electricity. If none of this helps note the plug that connects the power supply to the organ. Unplug it and take the power supply in to be tested. A good piano service place should be able to direct you to someone. Also remember that something had to make the power supply fail if it is indeed faulty. None of this is simple or recommended for a person who has no experience with electricity or electronic repair. If you feel at all hesitant about doing it you are better advised to consult a repair person. If you do have experience but no schematic you can still usually find the problem with careful thought and procedure. Break the circuit down into modules and test them one at a time starting with the power supply. It could be something as simple as a frayed cord or blown fuse to something as complex as a burned out transistor or faulty tube ( in the case of older organs) causing the power supply to fail. I once repaired a home organ that the power supply blew in again because of the customers house wiring. That particular wall plug in had been wired improperly. Hope all this helps.

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. 
There are two issues to check, before proceeding please read the following note.
 (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. 
open the box and locate the power on button, clean using a Dielectric cleaning agent, can be obtained at most electronic specialty stores. 
clean the power button, may work but doubtful, usually the switch itself is usually bad, there is a way to test the switch, however, that is beyond the scope of this answer, if you are following this you will most likely have the knowledge to do this. 
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. 
If you test your power switch determine that it is good then you should consider getting the unit serviced by a technician. 
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, 
an example, in a local TV repair shop, a friend brought in a wide screen Plasma HD TV, quoted repair, $654.00  problem, 
power supply, actual cost, $75.00 my friend ordered the part online and with the help of a friend installed the new power supply returning his unit to full functionality. 
So beware,