B&K ST 202 Plus schematics

Discussion in 'Solid State' started by japon, Jun 9, 2008.

  1. japon

    japon Active Member

    Messages:
    101
    Location:
    Toronto, Canada
    I'm trying to resurrect a B&K ST 202 Plus amp. Had two bad output transistors which were replaced. Put in all fuses and nothing blows on startup. Have the board I replaced the transistors on with a DC offset of 1.2 volts. The other channel reads 14 mV but runs hot. Have read that it could be the input differential pair. I do not have any documentation for this amp. Does anyone out there have anything? Thanks.
     
  2. thedelihaus

    thedelihaus Nocturnal transmissions

    Messages:
    29,336
    Location:
    Boston Area, Massachusetts
    I have a 202 I just picked up this weekend- would any photos help? I think you're looking for more than that, but it's what I can offer.
     
  3. Rootpusher

    Rootpusher Member

    Messages:
    87
    I've owned and enjoyed a B&K Pro-10 preamp and B&K EX442 dual mono power amp for years; both Sonata series.

    In my experience, B&K customer service and support of older products is exceptionally good; don't hesitate to contact them for help:

    http://www.bkcomp.com/

    Even though they're mostly a "home theater" company these days :boring: I got the sense from a chat with an engineer there that they have a lot of fondness for their older "audiophile" 2-channel gear.
     
  4. gearhound

    gearhound Lunatic Member

    Messages:
    10,115
    Location:
    Santa Fe, New Mexico
    B&K customer service is top rate.
    Twice I called up with questions....and got very quick answers.
    I'm the original owner of these:
    1988 B&K Pro 5 pre-amp
    1988 B&K ST-140 power amp

    Steve
     
  5. thedelihaus

    thedelihaus Nocturnal transmissions

    Messages:
    29,336
    Location:
    Boston Area, Massachusetts
    This is good to know about B&K.

    I now own an ST-202 and an EX-442 Sonata, and missed out on a HT receiver by minutes a bit back.

    I like dealing with companies that offer exceptional support. Another reason I'm fond of Thiel and of Vandersteen.




    I would think if they still are in the business of servicing the older gear, they may not be quick to give up the schematics.



    I dunno how they'll address this, but I wish you luck.

    B&K is great gear.
     
  6. japon

    japon Active Member

    Messages:
    101
    Location:
    Toronto, Canada
    Thanks guys. sent them an email. Hope they have a schematic they can send me. Cheers!
     
  7. grateful

    grateful Super Member

    Messages:
    3,052
    Location:
    Mass
    Ohm out the driver transistors and all the rest of the parts on the blown channel. On the other channel you should see + and - .6 volts on the output transistor bases. If the channel is hot turn down the bias pot a bit.
     

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