Bush TV135R and TV135RU buzz on sound
These models use a printed circuit for the sound amp, frame amp/osc and line osc. A fault that put frame buzz/hum that varies with frame Osc speed was usually traced to the securing screws that are the chassis connection for the small pcb. This put the frame waveform into the sound amplifier. Cleaning under the screws clears the fault but for a permanent cure I used a small piece of wire to solder the pcb connection to the chassis, easily done and a permanent cure.