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DBX 900 Mods

Discussion in 'Tech Talk - Electronic Repair Modifications DIY' started by Link555, Apr 30, 2020.

  1. Link555

    Link555 Well-Known Member

    Joined:
    Mar 31, 2007
    Location:
    North Vancouver
    This 900a Series is in to get TRS jacks in to replace the terminal connectors. I made a Custom PCB to replace the board mount terminal connector and reuse the original metal work with a 3D printed mounting plate.
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    IMG_7983.JPG CTMN4293.JPG
     
  2. Link555

    Link555 Well-Known Member

    Joined:
    Mar 31, 2007
    Location:
    North Vancouver
    Circuit boards came today... a couple stand offs and 3D printed insert and this will work!
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    kmetal likes this.
  3. Link555

    Link555 Well-Known Member

    Joined:
    Mar 31, 2007
    Location:
    North Vancouver
    IMG_0619.JPG Desoldering was a lot of work.....but it's finally done..
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  4. Boswell

    Boswell Moderator Well-Known Member

    Joined:
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    Location:
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    Nice work!
     
    Link555 likes this.
  5. Link555

    Link555 Well-Known Member

    Joined:
    Mar 31, 2007
    Location:
    North Vancouver
    Now onto the Power supply. Just doing some recapping. Interesting design the Power transistors are connector mounted...
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    kmetal and Kurt Foster like this.
  6. Link555

    Link555 Well-Known Member

    Joined:
    Mar 31, 2007
    Location:
    North Vancouver
    One more of the PCBA
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    kmetal and Kurt Foster like this.
  7. Boswell

    Boswell Moderator Well-Known Member

    Joined:
    Apr 19, 2006
    Location:
    UK
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    Ah-ha, the old TO-127 package! It looks like the middle 4 Darlington transistors are in this package mating with the 0.156" connectors. The outer two regulators are conventional TO-220, going directly into 0.1" sockets.

    Easy to take apart, but it's a very unreliable way of connecting to power device leads. Any increase in contact resistance through ageing can quickly build into a run-away failure.
     
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  8. Link555

    Link555 Well-Known Member

    Joined:
    Mar 31, 2007
    Location:
    North Vancouver
    Exactly what I was thinking, I might be taking that connector off and soldering straight to the pcb
     
  9. Link555

    Link555 Well-Known Member

    Joined:
    Mar 31, 2007
    Location:
    North Vancouver
    Well the plate is done.... 38 holes and two squares later... not bad for a sparky..
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  10. Boswell

    Boswell Moderator Well-Known Member

    Joined:
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    Pretty impressive! Is the rear panel in the same position as it was originally, or did you have to move it back a bit to cater for the length of the TRS sockets?
     
  11. Link555

    Link555 Well-Known Member

    Joined:
    Mar 31, 2007
    Location:
    North Vancouver
    Actually I brought the back out further, the racks has wings the project backwards ...so it works
     
  12. Link555

    Link555 Well-Known Member

    Joined:
    Mar 31, 2007
    Location:
    North Vancouver
    Power Supply Recapped and Transistors and IC soldered directly to the PCB. I removed the connector to hopefully increase the future reliability...

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    kmetal likes this.
  13. Link555

    Link555 Well-Known Member

    Joined:
    Mar 31, 2007
    Location:
    North Vancouver
    With a little fiddling I got the DBX 900 chassis back together and working.... Now onto the card repairs...
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    kmetal likes this.
  14. Link555

    Link555 Well-Known Member

    Joined:
    Mar 31, 2007
    Location:
    North Vancouver
    And now repairing 8 dbx 900 series cards... 6 904 noise gates and 2 903 compressors.
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    One compressor was the worst off three funky opamps and one internally disconnected 20k threshold pot.
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    kmetal likes this.
  15. Link555

    Link555 Well-Known Member

    Joined:
    Mar 31, 2007
    Location:
    North Vancouver
    Repairs done cards inserted and blank off panel made...tested and ready for pick up...
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    kmetal likes this.
  16. Boswell

    Boswell Moderator Well-Known Member

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    Looks like.a job well done!
     
    Link555 likes this.
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