Beomaster 2400

26th August 2008

The left hand channel of the FM tuner section of this receiver was initially silent but eventually gave weak, distorted output if the set was left switched on. As the tape input worked normally the amplifier section was deemed to be in good working order and attention focussed instead on the stereo decoder. The decoder chip IC2 was replaced but this made no difference, the faulty component being the coupling capacitor C201. A small leak had biased the following transistor into full conduction, removing the signal. The high value of the biasing resistors for the transistor’s base clearly makes this stage very sensitive to any leaks in the coupling capacitors. The equivalent capacitor in the right channel is C301. [Beomaster 2400]