Trouble-Shooting Tips
AMPLIFIERS 
Is the problem in channel one, two or both channels? Other Problems? 
TIP-If your amplifier is in protect mode, be sure to check your speaker cables and make sure you are loading the amp appropriately. Normally, an amp will overheat and shut down after a short time if it is trying to drive more speakers than it was designed to handle.
INSTRUMENT AMPS 
Are the problems with: instrument inputs, tone, volume controls, other controls: (Chorus, Reverb, Compresion, etc.), speaker output, operational/other?? 
TIP-Be sure to check the instrument cable. Also, if at all  possible, test your instrument on another amp.  You may think you have a problem with your instrument amp when it is really your instrument.
KEYBOARDS 
Are the problems with: Keys, function buttons/display, joystick, pitch bend, mod control, audio output, midi in/out, floppy drive, other peripherals, operational/other?? 
TIP-Many problems with todays keyboards are a result of a programming error or system glitch. After all, they are really a computer. A call to the product specialist at your keyboardís manufacturer may save you from having to send it in for service.
MIXERS/POWERED MIXERS 
Are the problems with: Input channels, master section, subgroups, Left/right aux. send/returns-effects send/returns 
monitor sends? For powered mixers-any problems with speaker outputs-see amp section. 
TIP-Be sure to eliminate the possibility that you have a defective patch cable. Try replacing any cable for a suspect input/output with a known good cable to see if it solves the problem. Remember, the more you troubleshoot and narrow down a specific problem, the less time it will take us to find it. That equals faster turnaround and lower repair charge! For powered mixers; normally, an amp will overheat and shut down after a short time if it is trying to drive more speakers than it was designed to handle. Check speaker cables!
OTHER 
Please describe the symptoms the equipment is displaying. Try to avoid troubleshooting the problem for us. Stating that you believe there is a short is an opinion. Describing how it sounds before the fuse blows describes symptoms.