I own a Mordaunt-Short ms 907w subwoofer. It is disconnected from the reciever and when plugged into the electrical outlet it hums. What is the problem?
Hello. I appreciate this is an old post but in case someone still has one of these.I just got one in for repair today. Get two rca connectors and short them out so the input is grounded. If this fixes the problem then it is coming in through the inputs. If not then the two large filter caps need replacing. Another problem these units have is the glue that holds the small filter caps etc corrodes the board after a few years. Clean it off, repair the tracks and coat the board with pcb lacquer.
SOURCE: Mordaunt Short Avant 309i subwoofer set-up
Lots of ways. To set it up properly you will need a decibel meter, Radio Shack makes a nice one. With the meter volume can easily be set as well as phase. I'm assuming frequency is the crossover frequency, generally set at 80Hz. This one involves some trial and error as I am not familiar with your speakers. Don't know much about the notch filter. A good resource for setting up subs can be found at: http://www.hometheatershack.com/forums/bfd-rew-forum/index3.html
SOURCE: Subwoofer hum
Hi,
Based on your description, the internal power supply of the subwoofer amplifier would be suspect. Often it would be a blistered or leaking filter capacitor. It is a relatively easy/inexpensive repair.
Hope this be of initial help/idea. Pls post back how things turned up or should you need additional information. Good luck and kind regards. Thank you for using FixYa.
SOURCE: Miller & Kreisel Subwoofer 60Hz hum
My MX 200 recently started humming even with no input signal line connected. Smitty8000 was correct and all I had to do was exercise the volume knob to make the problem go away. It seems when it sets for years with out being changed the wiper loses contact. A good vigorous repeated moving of the knob fixed the problem -- at first it made did some thumping while turning the know but this went away as did the hum.
SOURCE: mordaunt short ms409w subwoofer rear panel removal
You don't have to cut the speaker wires.
Under the foam wrapping is a connector - just unclip it!
SOURCE: Sunfire MK II Subwoofer hum. I have a Sunfire MK
you have a ground loop issue you could purchase a ground loop isolator, jensen makes them for about 40 bucks.I have discovered that if you have cable tv, unplug the incoming cable in your cable box and see if hum disappears.
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