Beomaster 900K

20th December 2012

Weak operation of the stereo indicator lamp if an FM stereo decoder is fitted is a common problem with these models due to the poor current gain of the original circuit. Matters can be greatly improved by adding an extra BD135 transistor which is easily mounted on the noval plug that connects the decoder to the main chassis. Disconnect the purple wire from pin 7 of the plug and connect this to the base of the BD135, then connect the emitter to the now vacant pin 7 of the plug and the collector to pin 6. A 100nF 63V ceramic capacitor should also be connected across pins 6 and 7. If the indicator still performs poorly check the existing driver transistor AC128I (AC128) for leakage and broken connections (it is easily damaged if the amplifier panel is opened carelessly) and the alignment of the decoder. [Beomaster 900K, Beomaster 900M, Beomaster 900RG]