Gutting an old Infinity BU-120 subwoofer...

Discussion in 'Archived Threads 2001-2004' started by Patrick Sun, Mar 7, 2002.

  1. Patrick Sun

    Patrick Sun Moderator
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    The amp is shot on this old Infinity BU-120 sub. What's funny is that I found two 10uF capacitor covers blown up, but I can only locate one of their mounts on the circuit board. I thought about trying to replaced the blown caps, but since I can't locate the second location, I'm just going to let the amp slide (or try to find the Infinity parts phone number and order a replacement amp - if anyone has the number please let me know).

    So what should I do with this otherwise "in good shape" sub enclosure and driver? I'd try another plate amp, but there's a brace in the way of enlarging the plate amp hole, and I really don't want to do a lot to retrofit an amp in there.

    There's two 2" ports 8.5" long (I think, need to double width/length). I need to figure what the tune is for the box (BTW, they used plastic flared opening with dense paper for the actual ports (like inner paper towel rolls). Kinda cheesy, but most people would never see it. There's a slab of insulation used for the stuffing inside as well.

    I'm gussing internal volume is around 1 ft^3.

    Any ideas?
     
  2. Rick Guynn

    Rick Guynn Second Unit

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    You could just make a plate to go over the existing amp cutout and mount some banana jacks on it. Then get a new plate amp and mount it in a box or a seperate rack-type amp and connect it up to the sub.

    It would be a lot less work than making a new enclosure. Of course, if you *want* to make a new enclosure for the fun of it.....

    --my 2 cents --
     
  3. Patrick Sun

    Patrick Sun Moderator
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    A kind person emailed me a PDF of the service manual for this subwoofer model, and hopefully it'll only take replacing 2 capacitors and 2 resistors to fix the problem with the amp (if not, I'm only out a few bucks). It seems this is a common problem for this amp (the originally used a 10uF 50V Non-polar cap, and the fix is to put in a beefier 10uF 100V non-polar cap (and replace any incidental parts in that signal path). If it still doesn't work, I'll be back... [​IMG]
     
  4. Rick Guynn

    Rick Guynn Second Unit

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    I wish the problem with the amp on my sub was as easy to diagnose [​IMG]
     
  5. Mike Lazalier

    Mike Lazalier Auditioning

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    I had a BU-2 amp blow-up.

    I just installed an adire audio AVA250 with just a little modification to the original amp cutout.

    I just cut out the part of the mdf where the original amp is recessed.

    I hope this helps.

    Mike
     
  6. Patrick Sun

    Patrick Sun Moderator
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    Well, that didn't work, so I'm totally thrashing the amp repair idea.
     

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