This article revisits a complete restoration of a Beocord 9000 cassette deck, focusing on the replacement of electrolytic capacitors for improved long-term reliability. While not as crucial as with amplifiers due to lower operating temperatures, capacitor replacement is recommended for optimal performance.
The Beocord 9000, designed for serviceability, allows access to its numerous electrolytic capacitors. Unlike its predecessors, it offers easier access by removing the front and back panels instead of extracting the main circuit boards.
The following images illustrate the process:
Front panels removed:
Bottom panel removed:
Ideal service position:
With the unit securely positioned, each capacitor is meticulously replaced, paying close attention to polarity. This process, while requiring focus, can be quite satisfying.
Two boards, #11 (DAC) and #13 (Oscillator Detector), necessitate removal for capacitor replacement due to their layered design.
Board #11 (DAC):
Before:
After:
Board #13 (Oscillator Detector):
Before:
After:
The remaining boards can be serviced in place.
Board #8 (Microphone Amplifier):
Before (shield removed):
After (shield reinstalled):
Board #3 (Rec/Playback Circuit):
Before:
After:
Board #6 (Rectifier):
Before:
After:
It’s noteworthy that the large 5000 uF capacitor on this board was nearing its end-of-life, measuring only 4000 uF. This further justified the decision for a full capacitor replacement.
Board #4 (Power Supply):
Before:
After:
Board #1 (Microcomputer/Display Circuit):
Lower section before:
Lower section after:
Upper section after capacitor replacement:
Board #2 (Dolby Circuits):
Before:
After:
With all capacitors replaced, the Beocord 9000 is well on its way to many more years of reliable operation.