Hello I am trying to decide if a QSC PLX3002 is too old to buy. It is my understanding that once capacitors get around 20 years old they have lost a lot of their capacitance (dried up). I don't know exactly how old the units are that I am looking at. But I saw an owners manual online that shows a copyright date of 1998 & 1999. That is approaching 18 years old for some of them. Here is the manual I saw, page 5: http://www.qsc.com/resource-files/p...continued/plx/q_amp_plx_series_usermanual.pdf How long did they make these ? Is there any way to tell how old a unit is ? Is it possible to tell by the serial number ? When did they stop making these ? When is a piece of electronic gear too old to buy without it being refurbished with new capacitors and anything else that might be needed ? Any help on this would be greatly appreciated .