Stereo amp repair help!

Discussion in 'General Electronics Chat' started by mchammer9111, Jan 24, 2013.

  1. mchammer9111

    Thread Starter New Member

    Jan 24, 2013
    Hi I have a set of klipsch promedia speakers and the left channel recently died. The left speaker appears to have been damaged in the process because when I use it as the right speaker it sounds terrible. I found the schematics here : promedia subwoofer repair - page 1.html

    I'm pretty much broke at the moment and I figure I better put my basic circuit skills to the test.

    Any idea where I should start testing? I was thinking of starting with the transistors on the left channel amp.
  2. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    Please post clear, high resolution photos of both sides of the entire circuit board, labeling any wires coming into/out of the board. Use the paperclip to add them as attachments to your post.

    Good focus and lighting is an absolute must.

    Without references, troubleshooting is nearly impossible. With photos, some here have fully rebuilt amplifiers.
  3. bountyhunter

    Well-Known Member

    Sep 7, 2009
    It has discrete amplifiers with no kind of overload protection and the usual cheap bias setting design. If something failed in the speaker it could have blown the amp, but more likely something failed in the amp that screwed up the bias point of the output and it cranked a DC voltage and current through the speaker and destroyed something like the voice coil. It's pretty hard to point to a single component because designs with no protection go out with massive destruction.
  4. sheldons

    Active Member

    Oct 26, 2011
    ok well looking at the power amplifier schematics its not a really hard amplifier to repair....the speaker has no doubt failed due to a fault either in the op stage-id b testing op transistors for sc all ways,check the driver stage for faulty transistors,diodes etc....just as a start but you will need need to be able to solder/desolder to a reasonable standard to avoid any more damage to the board ...also check for oc copper tracks as well