I finally got around to looking into the not-working volume wheel (encoder). I put a strong LED flashlight on it, and it worked. This told me that the IR emitter in the encoder pickup must have died. A voltage measurement across the diode confirmed this suspicion. The entire 5V showed on the meter, indicating that no current flows through the limiter resistor.
I replaced the emitter with a "OPTEK TECHNOLOGY - OP240A - IR EMITTER 890NM 0.76MM SIDE LOOKING" from Newark (08F2957). The device has exactly the same package as the original defective unit and pops right in. It has a wavelength of 890 nm and a 1.8V voltage drop. The encoder works now like new.
Beolover provides professional Bang&Olufsen maintenance and restoration services. We give one year warranty on parts and labor. All parts featured on the blog are also available to other enthusiasts for their restoration projects. Please, send an email to beolover@gmail.com or use the contact form on the side bar. Enjoy the blog!
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