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Problems with Raven Labs MDB-1...help!

Discussion in 'Amps and Cabs [BG]' started by Ricky Caboverde, Jul 14, 2013.

  1. Jul 14, 2013 #1
    Ricky Caboverde

    Ricky Caboverde Supporting Member

    Feb 26, 2004
    Miami, FL
    Hi guys,
    Has anyone here experienced distorted output from a MDB-1 preamp/DI? It's happening with all three channels and I don't why it's happening. Since the PCB seems to be easily serviceable...I was hoping one of you might have some experience to impart on this issue ;)

    Thanks in advance!
     
  2. Jul 14, 2013 #2
    Ricky Caboverde

    Ricky Caboverde Supporting Member

    Feb 26, 2004
    Miami, FL
    And please forgive me if I posted this in the wrong forum.
     
  3. Jul 14, 2013 #3
    MuthaFunk

    MuthaFunk

    May 8, 2007
    GTA Ontario Canada
    Batteries good, power supply ok?
     
  4. Jul 14, 2013 #4
    Ricky Caboverde

    Ricky Caboverde Supporting Member

    Feb 26, 2004
    Miami, FL
    I was just using the power supply without any batteries (in case they were drained). I can try it again with just batteries, but I think it will be the same outcome :/
     
  5. Jul 14, 2013 #5
    MuthaFunk

    MuthaFunk

    May 8, 2007
    GTA Ontario Canada
    Well there doesn't seem to be a schematic available online easily however usually problems like you described are caused by a poor joint somewhere. I don't think that particular Pre is too complex so a tech could probably troubleshoot it pretty quick. Unless your handy with a soldiering iron... If you have a steady hand you could try to remove and reseat the op-amp chips inside. There's likely one for each input plus one or more thats common to all of the inputs that drive the outputs. Does the distortion come out of the XLR as well?
     
  6. Jul 14, 2013 #6
    Ricky Caboverde

    Ricky Caboverde Supporting Member

    Feb 26, 2004
    Miami, FL
    It distorts on both line out and DI. I can try fiddling with the chips. I'm pretty decent with a soldering iron, but I wouldn't know what to check for ...everything looked pretty clean inside but I do know that it has been worked on before by a tech a few years back.
     
  7. Jul 14, 2013 #7
    MuthaFunk

    MuthaFunk

    May 8, 2007
    GTA Ontario Canada
    Check the output connections at the 1/4" jack. You could re-flow all the connections there if you're really not interested in taking it to a tech. Also, consider re-flowing the connections on the volume pot and anywhere else that looks suspect. You can play a signal and listen for the problem to get better or worse while you poke around with a non conductive stick (chop stick) at components and flex the board to help locate a poor connection.
     
  8. Jul 16, 2013 #8
    Ricky Caboverde

    Ricky Caboverde Supporting Member

    Feb 26, 2004
    Miami, FL
    OK, I was able to fiddle some today and think the issue is power related. I never paid attention to the power light before, but just realized that the green power light is very faint when I use the ac adapter and does not come on at all when I use batteries.
     
  9. Jul 18, 2013 #9
    MuthaFunk

    MuthaFunk

    May 8, 2007
    GTA Ontario Canada
    You'll have to find the point that's common to both the battery and AC adapter input jack that is a poor joint. Try the non conductive stick method or if you have a ohm meter you can start testing continuity from the battery / DC in points to the main circuit board and look for high resistance or a broken or frayed wire. I'd love to see pics of the inside of that unit. I'm an admirer of Steve Rabes SWR products and never seen a gut shot of any Raven Labs equipment. .
     
  10. Jul 18, 2013 #10
    Ricky Caboverde

    Ricky Caboverde Supporting Member

    Feb 26, 2004
    Miami, FL
    Thanks man. It's been a long day...pics this weekend. Promise. I might hrow in some APD-1 and PHA-1 pics too....really cool stuff :cool:
     
  11. Jul 18, 2013 #11
    Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    I've repaired many a broken circuit board trace or broken solder joint right where the switching contact on the adapter meets the pad, but not specifically on this piece.
     
  12. Jul 21, 2013 #12
    Ricky Caboverde

    Ricky Caboverde Supporting Member

    Feb 26, 2004
    Miami, FL
    MDB-1

    IMG_20130720_191455_zpse6660a87.jpg

    PHA-1

    IMG_20130720_191936_zps01b039b3.jpg

    APD-1

    IMG_20130720_192441_zps51e0a0f5.jpg

    True Blue EQ

    IMG_20130725_2243481_zps7af7a04a.jpg

    IMG_20130725_2244081_zpsc6b98774.jpg
     
  13. Jul 22, 2013 #13
    MuthaFunk

    MuthaFunk

    May 8, 2007
    GTA Ontario Canada
    Very nice. Thanks for posting.
     
  14. Jul 22, 2013 #14
    Ricky Caboverde

    Ricky Caboverde Supporting Member

    Feb 26, 2004
    Miami, FL
    You guys are brilliant!!!!

    I just reflowed some ugly spots at points where both battery and adapter have connections and popped in some batteries. When I clicked the power switch and saw a bright green light, I almost didn't want to believe it. The MDB-1 works like a champ now! Radiohead (test audio) is coming through absolutely clean, clear and punchy through the line out into my pha-1 :thumbup:


    Thanks so much guys :D
     
  15. Jul 23, 2013 #15
    MuthaFunk

    MuthaFunk

    May 8, 2007
    GTA Ontario Canada
    Glad to hear its back in service. I love the craftsmenship of the Raven Labs stuff. I'm sure you'll get years of service out of it now.
     
  16. Jul 26, 2013 #16
    Ricky Caboverde

    Ricky Caboverde Supporting Member

    Feb 26, 2004
    Miami, FL
    Just added pics of the True Blue EQ!

    Steve's arrangement of serial numbers seems strange to me. They don't seems to be successive according to date at all (i.e., #122 - yr.2002; #435 - yr.2002; #445 - yr.2001). And I wonder how many of these units did he make before retiring Raven Labs?