General Description. , The models 527-MA and 528-MA are mantel models housed in moulded plastic cabinets. Features of design include: Tropic-proof construction, automatic volume control, magnetite cores in I.F. Transformers and broadcast oscillator coils, air-dielectric trimming capacitors, extension Speaker terminals, pick-up terminals, A.C. outlet for Electric Clock, Record Player or F.M Tuner and a straight-line edge lighted plastic dial scale. CHASSIS REMOVAL First remove the cabinet back. It is fastened to the cabinet by four screws. Then remove the control knobs by pulling them straight off their spindles. The chassis is held in position by two screws through the base of the cabinet. Removal of these enables the chassis to be withdrawn from the cabinet. When replacing the cabinet back, make sure that the power cord passes through the slot provided in the bottom of the cabinet back.