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Sony subwoofer WMSP87

 
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yogidbear
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PostPosted: Wed Jan 11, 2006 3:15 am    Post subject: Sony subwoofer WMSP87 Reply with quote

Hi, sorry if this isnt the correct place, but i need help. I have a sony subwoofer with built-in amp. model number is SA-WMSP87, There is a 125volt 3.15(maybe 3.75 cant really tell) amp fuse. I went to radio shack and found a 125volt 4amp fuse, but it blew assoon as i powered the unit on. Anyone know what could be causing the fuse to blow? or should i just get a multimeter and check each connection?
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Zieggy
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PostPosted: Wed Jan 11, 2006 9:12 am    Post subject: Sony subwoofer Reply with quote

Hi - hate to say it, but it looks like this needs more than a fuse. ANYtime a fuse pop insantly, there is some kind of serious overload. In this case the most likely culprit is the power output IC.
Are there any cooked resisters?
like maybe a 100 ohm 1/4 watt someplace?? (brown, black, brown)
this would tend to point to the output IC - NOT the resisters

Next bet might be the power supply. Is there a power transformer?
It could be a shorted rectifier diode.
If there is no Power transformer, and it is a switching power supply -
USE GREAT CARE!! there is easily enough voltage in a simple switching power supply for you to suddenly quit carring if the subwoofer ever woofs again.

if the output IC is shorted, the resistance across the power supply would be very low - less than 5 ohms. First - with all power removed, jumper across the two large filter caps - be sure they are fully discharged - now on the ohm scale - measure from the positive side to the negative side - if the resistance is below 5 ohms, chances are very good the output IC is shot.
Replace - test - enjoy Smile
Best
Z
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PostPosted: Wed Jan 11, 2006 3:01 pm    Post subject: Reply with quote

awesome reply! i'll check out all of these things.
apon closer inspection i found a white box(i dont know what it is exactly so ill describe it) has 3 wires(not really wires but yeah its metal and sticking out) its about an inch and a half wide, inch tall(wires abit taller) and a quater of an inch thick(or thinner), this white box is cracked about halfway down, and has a brown mark on it just under the crack(both sides of the white box). nothing else seems to be burned out or damaged in anyway.

sorry for not knowing exactly what that white box is, i can take a picture of it if needed, and i dont know how to do what your asking at the end of your post (noob to electric and audio insides and such).

there is a power supply section and then another section to the insides of the sub box, excluding the sub itself, the second section is where the white box is, and seems to be easily replaced (assuming a replacement part can be found), because i strongly doubt i can repair it.

thanks for the very imformative reply and i hope you can find it in your heart to reply again.
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