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Old 27th August 2008, 12:43 PM   #1
jton219 is offline jton219  United States
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Default help fixing class D amp..

i own an infinity basslink powered car audio subwoofer. its a 10inch subwoofer powered by its own 200watt class D amo. the amp blew a few months ago. i havnt had the time to try to fix it until last week. i opened up the amp and saw a blown capacitor rated at 1000uf, 80v 105 degree c. i replaced the blown cap with a new one, tried firing up the amp and its still broken. i didnt see any other noticeable shorts on the board. don't know what to do next.

amp symtoms- power LED is on, the servo light (lights up to notify you when the woofer is at max excursion) blinks occasionally during heavy bass notes.. no output from the subwoofer, it blows 25a ato fuses all day. i remember hearing 2 or 2 loud non musical thumps from the woofer before it blew.
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Old 27th August 2008, 01:15 PM   #2
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hi,
you gotta test output fets (probably one pair).

Probably blown (=shorted)

what about your woofer ?

did it survive to full DC supply ?
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Old 27th August 2008, 10:36 PM   #3
jton219 is offline jton219  United States
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please excuse my noobiness.. please explain how to test a mosfet. the woofer seems good..i hooked it up to a 9 volt batt and it responds.i actually get a new a/b amp in today that i going to try to use to bring the basslink woofer back to life.
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Old 27th August 2008, 11:40 PM   #4
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The capacitor is not likely to be the main fault. It probably blew because the faulty circuit put too much stress on it (overvoltage, overcurrent or overheating of something close to it).
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Old 28th August 2008, 12:02 AM   #5
jton219 is offline jton219  United States
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do you guys think this thing is even worth fixing..or should i just dump it.
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Old 28th August 2008, 12:27 AM   #6
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Given that you don't know how to test for a shorted FET, it's probably more economic to replace it, but economics is not always the whole story.

w
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Old 9th September 2008, 03:11 PM   #7
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Default Basslink not working

Hi. I have the same issue. Unit powers on and just sits there. Anything anyone can suggest is greatl appreciated. $300. is an awful lot of money for me to simply throw it out and buy another one. I gotta try to fix this.
Thanks!
Jim
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Old 9th September 2008, 09:04 PM   #8
jton219 is offline jton219  United States
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it appears after blowing the amp, the speaker starts to go too. I hooked up the speaker to an external amplifier, resealed up the basslink so its air tight and it sounds really bad. the amp i'm using is from cadence and puts out 200 watts in bridge mode. it also causes the amp to go into safe mode after switching sources from radio to cd or whatever. some have told me the voice coil is starting to go and the amp and the impedance is lower than its spose to be, thats why someitmes the amp goes into safe mode.
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Old 9th September 2008, 10:24 PM   #9
Eva is offline Eva  Spain
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Could you measure voice coil resistance with a multimeter? Remember to substract the result that you get when you join both test leads directly from the measured value.
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Old 9th September 2008, 10:36 PM   #10
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If it sounds bad, either the voice coil is half molten or the amp u hooked up is bad.
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