Repair of a Musical Fidelity Elektra E100

Musical Fidelity Electra E100 integrated amplifier

Musical Fidelity Electra E100 integrated amplifier

Last month a customer presented a nicely preserved Musical Fidelity Elektra E100 integrated amplifier for repair – the fault was that there was considerable mains hum audible from the loudspeakers on all inputs.

Further investigation in the workshop showed that the mains reservoir capacitors on the main circuit board which feed the power amplifiers were bulging and well past their sell by date. These were replaced fairly easily with modern equivalents which were physically much more compact than the originals.

Here is a pic of the main amplifier printed circuit board to allow the removal and replacement of the main power supply capacitors.

Circuit board removed from Musical Fidelity E100

Circuit board removed from Musical Fidelity E100

Here are the bulging resevoir capacitors that have seen far toom much action. Now that the main PCB is removed, we can easily change these four tired electrolytic capacitors for modern equivalents, which are incidently quite a bit more compact.

Faulty electrolytic power supply capacitors in Elektra E100 amp

Faulty electrolytic power supply capacitors in Elektra E100 amp

This is the reverse side of the main power amp PCB, ahowing star earthing technique and overheated parts of the PCB.

Star earthing and overheated tracks

Star earthing and overheated tracks

The pre-amp power supply capacitors at 220uF/ 35V were also found to be dried out and bulging and these were also replaced. The repair was effective and all mains hum removed, hopefully this Musical Fidelity amplifier will continue on for another 15 years good service without issue. Here is a link to a pdf file of the schematic circuit diagram for the Musical Fidelity E100 amplifier.

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About Phil Glazzard

Phil describes himself as an 'audio nut from an early age', and is the director of the company as well as our in-house repairs engineer and custom installer. He takes interest in all music forms and spends most of his free time playing the drums, or geeking it up with PIC microcontrollers. He can't resist a gadget.