Mordaunt Short MS308 amp repair - diyAudio
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Old 26th January 2013, 11:05 PM   #1
nps is offline nps  United Kingdom
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Default Mordaunt Short MS308 amp repair

I have a Mordaunt Short MS308 subwoofer that when powered up creates a constantly loud buzzing. This buzzing happens whenever the sub is powered up, regardless of whether it is set off auto or on. Though there is a increase in volume when it is on. I haven't been able to find a service guide, so was hoping somebody might have an idea as to what to look into. Can't see anything wrong visually, but my guess is that the amp has gone open circuit, still trying to extricate the amp board to check though. Any suggestions very much welcome.
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Old 28th January 2013, 12:45 PM   #2
nps is offline nps  United Kingdom
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Have succeeded in removing the amp board so have some more details. The chip is a TDA7294, there is also some discolouration on the bottom of the board localised around the connection from the signal processing/switch board above it. However none of the components appear damaged in anyway that i can see. There is a triangle followed by SK 07V0 on the board, when i searched for this i came up with a service manual for a Philips SW968, the amp board of this sub has the same marking but does not appear to be the same board.

Just to clarify the issue when any power is applied to the amp board then regardless of the position of the stand-by switch the cone goes to minimum excursion and then vibrates constantly.

Any ideas as to what might be wrong, or even better how to find out for myself, would be very much appreciated.
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Old 28th January 2013, 12:47 PM   #3
nps is offline nps  United Kingdom
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If somebody could move this to the chip amp forum it would be aprreciated, just realised it is in the wrong place.
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