Old Boston Acoustics subwoofer repair, BJT alternatives

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  • staze
    Member
    • Mar 2008
    • 41
    • USA
    #1

    Old Boston Acoustics subwoofer repair, BJT alternatives

    Working on an older Boston Acoustics HPS10SE, and while verifying voltages, I noticed one of the PSU BJTs is getting excessively hot and the voltage is dropping out on the 15V rail. Not sure that's actually an issue (I don't have everything plugged in, so maybe something is saturating on the positive end and dragging that rail down and the BJT overheating is cutting out).

    But, figure I need to buy some NP capacitors from mouser anyway, so might as well replace these. They're a H669A and H649A. Pretty "meh". They test fine out of circuit, but I can't really put a load on them and test that way.

    I suck at finding alternatives for transistors (I've had a few blow on me cause I missed some piece). But, it LOOKS like from some googling, the Toshiba TTA004 (https://www.mouser.com/ProductDetail/757-TTA004BQ) and TTC004 (https://www.mouser.com/ProductDetail/757-TTC004BQ) should work? Or should I just risk an ebay/alibaba purchase of some of the same 649 and 669 parts?

    Thanks! Attaching service manual that I grabbed off BA's site.
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