Help needed: Yamaha TRB JP1 service manual

Discussion in 'Pickups & Electronics [BG]' started by steweDbass, Mar 15, 2014.


  1. steweDbass

    steweDbass Commercial User

    Jun 9, 2013
    Tokyo Japan
    Bacchus / STR Endorsing Artist and direct Dealer of new and used MIJ Brands.
    Hello there,

    just servicing and refurbing my old TRB 6 (which is the same as the TRB JP1) as something has gone awry with the circuitry. I need the service manual for this model or close up pics of the circuitry so I can replace parts correctly.

    I looked around on the web but thus far to no avail, hence I am turning to fellow bass heads on this forum ;)
    Can any of you guys help with service manual or detailed pics of the circuit? :help:

    Thanks in advance:bassist:
     
  2. yama6patatuci

    yama6patatuci

    Aug 22, 2014
    What specifically happened with the circuitry? Was the EQ board? Just one of the controls? I have a JP1 that worked fine till a month ago when I just began to loose its signal. A local repair shop said that the mid boost/cut control needs to be replaced. The closest part I have found online was the the JP2 EQ circuit board etc. Nothing yet for my JP1. Yamaha sent me the service manual for it. Hope it's what you were looking for.

    Love the JP1 for sure!
    nigel
     

    Attached Files:

  3. steweDbass

    steweDbass Commercial User

    Jun 9, 2013
    Tokyo Japan
    Bacchus / STR Endorsing Artist and direct Dealer of new and used MIJ Brands.
    Actually I managed to fix it, just needed cleaning with contact cleaner and I had to shield the whole inside of the cavity to stop high frequency buzz on the treble pot. I also shielded the pick up cavities too for good measure. Maybe try the same, just clean the circuit board. Also make sure your pickups are still good using a multi meter, if they register below 8 then they may be losing potency and output. Seems the board was problem free though. There are some little attenuator dials (tiny blue boxes with white plus driver dials) on the board too, those can be adjusted to increase or decrease output on the preamp as far as I understand it.

    Cheers!
     
    yama6patatuci likes this.
  4. steweDbass

    steweDbass Commercial User

    Jun 9, 2013
    Tokyo Japan
    Bacchus / STR Endorsing Artist and direct Dealer of new and used MIJ Brands.
    PS thanks for the PDF!