REPAIR SHOP 

Repair of Mordaunt Short MS309W, Active Powered Subwoofer with 8" Aluminium Driver

Fault - Customer reported no output, 

The customer had taken the active amplifier chassis and back panel out of the main speaker cabinet to save on shipping,  

On test found that there was an output but there was a high frequency component riding on the output waveform.

Removed the back cover from the  amplifier assembly , on inspection found  that the 2 x  10uf 100V bipolar capacitors that sit on the output were burst and had  ejected dielectric all over the surrounding area of PCB, (see top left below)

. 

Removed PCB 

Cleaned up PCB fitted 2 new 10uf 100v Bi Polar capacitors, refitted the PCB and tested

As can be seen the waveform is now crystal clear with no high frequency component visible

Refitted the back cover and tested unit for 4 hours all ok 

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