REPAIR SHOP 

 

Repair of Mordaunt Short Premiere 309W, Active Powered Subwoofer with 8" Aluminium Driver

 

 

 

This is the 2nd one of these we have had in for repair

Fault - Dead, no output  

Removed the active amplifier assembly from the cabinet, on inspection found  the cause of the problem to be 2 blown fuses, after some fault finding found that both of the output devices had failed  with a short circuit on all 3 pins

See the removed  amplifier  assembly showing the 2 output devices - Hex fets IR640 and IR9640

 

Unsoldered and removed the PCB with the output devices also replaced 2 10 uf capacitors that were shot to pieces, this was probably the cause of the damage to the output devices.  

Replaced the output devices 

Reassembled the amplifier and tested - all now working perfectly, note the blobs of silicone to bond the cable loom covering down presumably these covers are to stop the cable looms resonating, also just about everything else is bonded in the same way.. 

Tested unit for 4 hours all ok 

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