Black OLED screen and no sound

[Faye108]

Hi,

I'm experiencing some strange issue with my Nsynth build. I already spent hours to troubleshoot, but couldn't source the problem. I am very desperate.

Everything seems to be working fine except:

• the OLED screen doesn't work (remains totally black)
• there is no sound at all
• since there is no sound, I don't know if midi signals get processed or not.

I already checked for any soldering bridges and checked for the right polarity of all components.
Even though I'm quite confident in my soldering skills, out of pure desperation I decided to build a second unit with a second set of components (including a new screen). As for the second unit, I followed this advice and left a tiny gap between the 2 PCB to avoid any solder bridges. To my surprise, the finished build shows EXACTLY the same issue as the first one.....

• I used Elecrow to produce the PCB according to the build instructions.
• I sourced and soldered all components myself (including SMD)
• I have a raspberry B+ with the 64gb image.
• I also tried it with a raspberry B, but still the same problem.
• Nsynth starts up normally. I logged in and successfully flashed the board.
• When I connect the Nsynth to a monitor via HDMI, the mini-screen appears on the upper left corner. I can see on the monitor that the encoders, the pots and the touch panel work completely fine.
• All pins on the OLED PCB have voltage. So unlike this user, it doesn't seem that bad solder joint are the cause of the problem.
• I bridged both the SJ1 and SJ2 on the OLED PCB.
• Running i2cdetect -y 1 shows MCU at 0x47, the display at 0x3d and a device at 0x4c.

Please help... :/