While all flaws from the former version 2.5a (blue) were fixed, I unfortunately introduced two new flaws:
Most important the 6 smoothing capacitors have no ground, which makes the sound humming if not fixed. Fix is easy, just remove small piece of the solder mask and create a connection to grounding surface around:
With the new OLED display there’s also a serious problem: Vcc (1) and GND (2) are interchanged. So please don’t connect it directly but use some kind of “adapter”.
For WPC the green board comes with an alternative power supply for the amplifiers: a adjustable DCDC step down regulator. Its easier to install and cheaper, but it needs to be adjusted in order not to overload the amplifiers. So please adjust output voltage to 12-15 V with the blue spindle pot.
The DCDC step down converter is an alternative to the linear regulator 72S15. Its an either or but not both installation. I reserve to deliver either one or the other depending on availability.
General advice with 3.96” connectors: remove the key pin before soldering! Take a pliers and pull it out. Newer boards have the key pin marked on pcb printing. For olders you need to check the original connector.