Marshall Major Mods

An early backup Major from Ritchie


Ritchies backup Major topside


Major untouched from 1970


Major detail


Major detail


Major early 70s years


Fixed Major


Fixed Major detail


Fixed Major detail


Heavy modded Major


Heavy modded Major 1969


Main transformer Major


Electronics Major


Recapped Major


Here the four mods to get the Major stable. See the details in red circles in schematics

First: Insert the OT protector diodes like shown.
Second: change the 4 pieces screengrid 250_Ohm Rs of KT88 to 1kOhm/ 10watt
Third: change the bias caps (2x 8uF) to 2x 47uF/ 160Volt
Fourth: change the feedback resistor (47kOhm) to 150kOhm




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