Tablet Mounting Guide

 

This guide covers all steps needed to mount the tablet in the bezel and to connect it.  It assumes you will be using:

 

  • The BobJ ruggedized tablet case w/aluminum U-bracket

  • Minibox DC-DC USB Power Supply 

  • Unitek 6 Port USB3 Hub with 2 5V / 2A charging ports

  • Optional USB DAC (such as HiFimeDIY Sabre USB DAC ES9023)

 

1. Aligning and mounting the tablet in the bezel

 

   1.1  Slide the U-bracket through the slots in the back of the BobJ case

   1.2  Insert the tablet into the case (making sure it is oriented correctly exposing the micro-USB connector)

   1.3  Insert the tablet w/case into the mounting bezel from the rear.  Make sure the tablet is oriented with the micro-USB on the right.

          The bottom of the tablet should be fully forward, and the top should be angled about 15 degrees forward so that the micro-USB connector

          is aligned with the slot in the tablet mounting bezel.

   1.4  Plug the micro-USB connector on the OTG Y-Cable into the tablet.  It should fit tight and be fully recessed in the slot.

   1.5  Insert the 3/8 in 8-32 machine screws into the left and right sides of the mounting bezel and through the holes in the U-bracket.
          After the tablet, tablet connector, and the U-bracket are aligned, tighten the machine screws.

 

2. Configuring the DC-DC USB Power Supply jumpers

 

   2.1  If you purchased the preconfigured Minibox power supply, you can skip this step (unless you want to change the settings).

   2.2  Remove the cover from the Minibox power supply and referring to the figure below, set the jumpers on the 8 position jumper
         strip labeled CONFIG as follows:

 

        Main mode = Automotive

  Output voltage = 12V (must be same as USB Hub input voltage)

Timing schemes = Off delay: 30 min, HardOFF: 1 min

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

With this configuration, the power supply output will be set to 12V and turn on when the IGN is turned to ON (not ACC).  It will remain ON powering the USB Hub and Tablet for 31 minutes after the ignition is turned OFF (or to ACC).  When the IGN is turned off, it will start the 30 minute countdown, and when this finishes, the power supply will remain on for 1 more minute. When the IGN is switched back to ON, the power supply and tablet will power up again as soon as power is detected, and reset the coundown timers.

 

3. Connecting the Minibox Power Supply and USB Hub

 

    3.1  Make sure the OTG Y-cable micro-USB plug is firmly plugged into the tablet and secured.   

    3.2  Attach the Minibox power supply to the 6in X 8in perf-board using 3/8 8-32 machine screws, and mount this assembly to the U-bracket using 
           Velcro adhesive backed tabs.

    3.3  Connect the input power cable (Bat, Ign, Gnd) to the 4 pin Molex Power Input connector

    3.4  Connect the output power cable (12V, Gnd) plugging the 4 pin Molex plug into the Minibox power supply output and the DC Coaxial Plug
           into the USB Hub power input jack.  

 

           If you are building this cable, the DC Coaxial Plug is 2.5mm ID x 5.5mm OD, the positive terminal is the inner ring and the ground is the

            outer sheath

    3.5  Magnetically attach the USB Hub to the Minibox power supply case using four Neodymium magnets glued to the bottom side of the USB Hub.

    3.6  Use a USB3.0 B-Male to USB3.0 A-Male cable to connect the USB Hub input to the OTG Cable connector.

    3.6  Plug the OTG Cable A-Male plug into one of the charging ports on the USB Hub.  A better fit is achieved using a 90 degree A-Male to A-Female

           adapter to make this connection.

 

    3.7  This completes these mounting and connection set.  I strongly recommend to test this assembly before before moving to the next stage.

    

           a. Connect the Power Input cable with BAT connected to 12V, IGN initially OFF, and GND connect to ground.  

               The Minibox power supply and USB Hub should be off, and the tablet should be in the deep sleep state.

           b. With 12V still connected to the BAT input, also connect IGN to 12V

               The Minibox power supply and USB Hub should power up (denoted by green LEDs), and the tablet should wake-up to the active state

               Open the Settings application on the tablet, and scroll to the USB Host sections.   If the Timur USB ROM has been properly installed and

               the tablet is properly connected, you should see: 

 

 

 

                                                                                                                   If you find the USB host mode is inactive, check to make sure that

                                                                                                                   the micro-USB connector is fully seated and making making good

                                                                                                                   connection to the tablet input and that the other end of the cable is

                                                                                                                   connected to the USB Hub input.

 

 

 

 

 

 

 

 

 

            c. If the previous step passed, remove 12V from the IGN input.  You may be able to see the Minibox power supply LED go from solid green to

                flashing green.  The USB Hub should continue to be powered and the tablet should remain active.  Following the programmed turn-off delay 

                (30 minutes), the USB Hub power should switch off and the tablet should go into deep sleep mode with the screen turned off.