Marshall JCM 800 2203 Guitar Amp - Tube Swap and Re-Biasing


Chris from Cornerstone joins us again for this Marshall re-biasing video.  This is an all original JCM 800 - 2203 that is receiving new tubes all around.  Of course, a quick inspection is in order.
     Measurements of the electrolytic caps show that most of the caps are good, one of the filter caps are about ready to go.
     As I make incremental adjustments to the bias as the tubes cook, The question is, are the tubes really balanced as the box from mesa advertises..   I'd think not. As a matter of fact, the tube deviation is 6 miliamps from all 4.  Good thing I was biasing for the highest current flowing tube.

     Robotube is fired...





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