My yamaha rx-v730 receiver won't turn on. when i pressed the power/standby button, i can only hear clicking sound and the unit remains off. before, my unit started to automatically turn-off and when i tried to switch it back on, "check sp wires" appeared on the display and then it remained on. but now, it can't be switched on at all. what seems to be the problem and how will i fix it?

SOURCE: Yamaha Receiver RX-V630 not working (resets itself immediately)

This maybe an easy one. Have you unhooked all the wires going in to the stereo. "SP wires" means you have wires to the speakers are touching and the stereo is shutting down to avoid overloading. Hope this helps...

SOURCE: Immediate shut

Unplug all the speaker wires first, then unplug the unit from the wall for at least 24 hours, The plug back in without the speaker wires or anything else plugged in. Then see if it goes to the protection mode. If it does not, plug in each speaker at a time, and see if any speaker, when hooked up, makes the receiver shut down. If it does shut down, My friend, I'm afraid you will need to take this unit into a repair shop, OR get a new unit. Good Luck

SOURCE: Yahama receiver Rx-630 not working

The problem might be caused by two major circumstances. 1)Touching wires 2)Overheating. I suggest you unplug all wires connected to the amp then turn on the amp. If it gets turned on then we know that the problem is that you have touching wires. If there is a short circuit somewhere, get rid of it. The ventilation is another important issue that you have to pay attention. It simply causes overheating.

SOURCE: Yamaha RX-V1 Power

Got the same problem and did some searching.
Strange thing is that next day the amp works fine.
This is what I found on http://www.forums.hcsd.com.au/Blah.pl?m-1210733289/s-8/

SYMPTOM: The power cannot be turned on, or the protection circuit is activated to turn off the power.
CAUSE: Fluid leakage occurs from the backup capacitor C633 0.047F 5.5V (C662 in the case of RX-V3000/DSP-AX2) on the Function PCB and causes a short with the adjacent components and between patterns, resulting in operation of the protection circuit. Fluid leakage tends to occur with this capacitor particularly with high internal cabinet temperatures, with or without the power on. Often, the leakage is only visible with very careful inspection.

SOLUTION: Two types of backup capacitors are now available with a longer expected service life. When servicing, thoroughly clean the leaked fluid from the PCB and from under any nearby components before replacing the capacitor. There are models other than those mentioned above that use the subject backup capacitor. Check them for fluid leakage and replace the capacitor as needed.
PART(S): Old
Ref. No. Part No. Description Remarks
C633 or
C662
VT740700
V3860300 ELECTROLYTIC CAP 0.047F/5.5V Vertical type
* VU545000 ELECTROLYTIC CAP 0.047F/5.5V
Horizontal type
New
Ref. No. Part No. Description Remarks
C633 or
C662 WD294400 ELECTROLYTIC CAP 0.047F/5.5V Vertical type
* WD292000 ELECTROLYTIC CAP 0.047F/5.5V Horizontal type

SOURCE: how can I reset all settings on my yamaha rx-v730

Use Advanced Setup mode - see the manual. From standby press both STANDBY + STRAIGHT buttons, then choose INIT / ALL.