Any chance you are working around florescent fixtures & lights or light switches with dimmers? That would be the cause of buzzing.
Rich
Marantz 22xx AM section Diagnosis and Repair -- Help Required
I have been refurbished about fifteen 2270's and the section that gives me the most trouble is the AM circuitry. I have replaced all transistors, diodes (1N60) and capacitors but that does not guarantee a fix. The AM section usually ends up with a lot of buzzing and may only pull in two or three stations. I have a scope, signal generator and a VTVM. I usually have to resort to buying a P150 board on eBay. I am willing to purchase more diagnoatic gear if it does the trick. Any help woud be appreciated. Thanks. Ray