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ARCHIVED FORUM -- April 2007 to March 2012
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This is the first Archived Forum which was active between 17th April 2007 and 1st March February 2012

 

Latest post 02-17-2009 7:43 AM by Folke. 4 replies.
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  • 02-14-2009 5:32 PM

    • Folke
    • Not Ranked
    • Joined on 10-24-2008
    • Stockholm, Sverige/Sweden
    • Posts 30
    • Bronze Member

    BeoCord 8002 one channel dead

    Hi, all!

    I just got a BeoCord 8002. It was advertised as "one channel not playing", and that is exactly the problem. Otherwise it seems to work. Belts are new. When playing a tape, only the Right channel is heard, and only the Right VU-meter will react. The two volume trimpots on the bottom are set one "notch" from the max setting.

    Is there anything obvious I can check? I have a DTM, and can do some soldering, but have very limited knowledge of electronics...so any help must be very precise, please! I can post pictures where you can draw arrows etc. to guide me... I have the service manual, but it is of very little use to me.

    I have cleaned the multi-pin contact leading from the tape heads to the PCB, and the relay next to it. Is there a way to measure the tape head, to see if it is faulty?

    Any help is greatly appreciated!

    /Folke


    BG 6000 Quad (two!), BM 3000, BM 5000 (2005), BV S45, BV M70 with trumpet stands

  • 02-15-2009 4:41 AM In reply to

    • Dillen
    • Top 10 Contributor
    • Joined on 02-14-2007
    • Copenhagen / Denmark
    • Posts 5,008
    • Founder

    Re: BeoCord 8002 one channel dead

    Probably a relay contact, a capacitor or a cracked solder somewhere.
    You will have to put an oscilloscope to the signal path to see where the signal is lost.

    Recently, I've noticed an increasing amount of faults related to the opamps used in these decks.

    Martin

  • 02-15-2009 7:33 AM In reply to

    • Folke
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    • Joined on 10-24-2008
    • Stockholm, Sverige/Sweden
    • Posts 30
    • Bronze Member

    Re: BeoCord 8002 one channel dead

    Thanks (again!), Martin! Yes -  thumbs up

    This is a fiendlishly complicated (but wonderful) machine, and I guess I’ll have to summon some local help with an oscilloscope...
    I only wonder if there are any likely suspects I can check? And if it’s possible to check the source itself, the tape head?

     

    /Folke

    BG 6000 Quad (two!), BM 3000, BM 5000 (2005), BV S45, BV M70 with trumpet stands

  • 02-15-2009 3:37 PM In reply to

    • Dillen
    • Top 10 Contributor
    • Joined on 02-14-2007
    • Copenhagen / Denmark
    • Posts 5,008
    • Founder

    Re: BeoCord 8002 one channel dead

    Of course you can measure the tapehead coils but defective heads are far between in these decks.

    The head relay and dolby relay (in some models) is far more likely candidates. Also cracked solders at the tapehead
    connector, the connectors between the two upper boards and where the ribbon cables meet the lower board.
    Also any cap in the signal path or even, as stated earlier, the LF353 opamps can be troublesome.

    Martin

  • 02-17-2009 7:43 AM In reply to

    • Folke
    • Not Ranked
    • Joined on 10-24-2008
    • Stockholm, Sverige/Sweden
    • Posts 30
    • Bronze Member

    Re: BeoCord 8002 one channel dead

    I think I must rule out the tape head first, before going any further. Exactly how do I measure the coils? Resistance over the two pairs of white/pink cables, as in my illustration?

    /Folke


    BG 6000 Quad (two!), BM 3000, BM 5000 (2005), BV S45, BV M70 with trumpet stands

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