I’m using a Heathkit SB220 since 1995. I bought it used. It has been built in 1980 by an Italian Amateur. This year I wanted to modernize it to keep it at a good level of performance.
Ho deciso di usare il kit RM-220 della Harbach Electronics. Il kit permette di sostituire completamente il sistema di retificazione e i circuiti di misura del PA.
I decided to use the RM-220 Harbach Electronics kit. It allows to sostitute the entire rectifier system and the meters circuits.
I took a few photos in order to follow easier the work step by step.
First disconnect the amplifier from the AC line, then remove any input, output and control cables from the rear panel. Place the amplifier on a book with front panel up.
Remove the bottom screws holding the feet and esternal container in place with amplifier. Put the screws and feet in safe place.
Lift the esternal container up and remove it from the amplifier.
Place the amplifier on the workshop’s bench with the front panel facing you.
Now the amplifier is ready for modification.