Audio Systems: Yamaha HTR-5640 receiver power issues, receiver power, audible sound

Question
Cleggsan,

I hope you can help me out with this. I was given a Yamaha HTR-5640 receiver from my father-in-law that wasn't used for about 2 yrs prior and claimed to be in great working condition when he stopped using it. Since I have had it, it will only turn on for maybe 1 second and then immediately turn off. I don't have any speakers except the bass but it was not connected. I just had the receiver plugged in. When I turn the unit on it makes an audible sound and then an identical sound when it shuts itself off. I took the cover off and it appears the sound comes from the back of the unit near the circuit board that the power cable is connected to. I would really like to be able to fix this and hopefully not have to pay more money than its worth to fix it. If you have any answers or suggestions, they are greatly welcomed. Thanks.

Answer
It is not a good idea to leave an electronic device in storage for so long a time. In fact, it does much damage by doing so.  The most common problem - I cannot say for sure this is what has happened to your unit but it is very likely it has - is shorted capacitors in the power supply caused by drying out when in storage for such a long period of time.  These caps are electrolytic products and require to be charged and discharged to keep them fresh and reliable.

Assuming this is what has happened it is easily corrected by replacing the electrolytics in the power supply.  This requires removing the covers and unsoldering the caps and replacing them with generics of the same value and maybe a little higher voltage rating.  It requires some advanced electronic and soldering skill but can be done with a couple hours of labor.

You may need the schematic to determine the parts replacement, but usually the are marked with their value.  Something like 470MFD and 50 volts or more.  They are polarized and the new replacement caps must be put in with the + and - in the same direction as the originals.

You can use generics so long as you can find a place to mount and secure them.  Sometimes there will be two caps in one can but you can use two individuals since duals are hard to find a Radio Shack.

More questions?  Let me know.