When i turned on the standby switch to start playing, the amp made a loud noise, like a pop, then no power. i tried other outlets, but still the red power light does not come on. i have a 1984 jcm 800 combo with one speaker its very old and has never been serviced by me. please help me!

It sounds as though at least Capacitor may have "popped" (blown the can apart), it should be easy to spot IF you are familiar with electronics, if not DO NOT attempt to "have a go at it" and take it to a reputable repairman.

by the way 1 capacitor is normally not the end of the problem, the chances are there will be several either "gone" or well on their way (any with "bulged" tops are also gone), the chances are it will be the power supply section - change EVERY capacitor in that section!

The JCM800 is a Valve amp and as such there can be some SERIOUS voltages flying about, so if you are not confident working on valve gear - DON'T TAKE THE RISK!