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Battery Drain Issue Greco GOB-1200 - Help needed !

Discussion in 'Basses [BG]' started by Z Axeman, Jun 9, 2020.

  1. Jun 9, 2020 #1
    Z Axeman

    Z Axeman

    May 15, 2015
    SoCal USA
    Anybody out there with knowledge on a late 70s early 80s Greco Pro GOB-1200 bass?

    I have a battery drain issue on it and wanted to reach out if there is anybody with knowledge on such issue. I'm looking for schematics or pictures of the internal setup to troubleshoot the issue that has been attended by my amp guy.

    He checked the input jack for proper functionality as well as the caps for leaks (replaced as needed), but the pre-amp still draws juice when not plugged in.

    Any help is appreciated ...
     
    Last edited: Jun 9, 2020
  2. Jun 9, 2020 #2
    Abner

    Abner

    Jan 2, 2011
    Mississauga
    Got any pics of the electronics? The jack itself?

    Might be somewhat similar to the Ibanez Musicians, built in the same factory. Check the Musician club thread and wiki for schematics and pics.
     
  3. Jun 9, 2020 #3
    Gunga Din

    Gunga Din

    Jun 22, 2018
    Got to be an incorrect wiring to the jack. IIRC, the sleeve lug (-) activates the battery when a jack is inserted.
     
    2playbass likes this.
  4. Jun 9, 2020 #4
    Abner

    Abner

    Jan 2, 2011
    Mississauga
    It very much depends on the design. The Ibanez guitars and basses of the late '70s and '80s were wired to accept an external 9-volt power supply. The switching and wiring on the jack was considerably more complicated than the typical stereo jack with battery negative to the ring.

    How many wires go to the output jack? And what type is it?
     
    Gunga Din likes this.
  5. Jun 9, 2020 #5
    Gunga Din

    Gunga Din

    Jun 22, 2018
    An outboard supply? Never knew that.

    I had an MC924 back in the early '80s. Loved that bass.
     
  6. Jun 9, 2020 #6
    Abner

    Abner

    Jan 2, 2011
    Mississauga
    Yup, stereo cable between the phantom power supply and the bass, +9 volts carried on the ring.

    Phantom power.JPG
     
    Gunga Din likes this.
  7. Jun 9, 2020 #7
    Gunga Din

    Gunga Din

    Jun 22, 2018
    Wow, I have never seen one of those. Well, except for the one I had with an Alembic Series 1. But never knew Ibbies used them.
    Thx for info.