I have a PV 2600 that when we powered it up both channels was working, all of sudden channel A went out and will occasionally make a popping noise.. can someone help me out here.. i have till friday t

SOURCE: i have Peavey Pv 2600

One side of the amp has failed and repair is NOT DIY. Take it in for servicing. This amp has many components in the power amp and repair is complicated. A failure can lead to 20 components being damaged. Failure to replace all damaged ones can result in immediate failure destroying the replaced ones.

SOURCE: i just bought a used valveking 100 half stack and

Same thing... they probably broke both jacks. Sometimes the guts of the jack is broken and it doesn't appear to be broken but is broken internally. You may find broken solder on the pins to these jacks as well.

Note that the two input jacks have a different gain.

Here is schematic: http://elektrotanya.com/peavey_valveking_100_212.pdf/download.html