PSS A50 stereo mod explained 

Well, not sure "the worst" fits the best, but at least "the most frustating"

Thanks @stuartcrossen2723

Thank-you Sergey ;-)

@@LionelN , following tightly your project. The keyboard has TONS of possibilities, but without stereo sound it's just kinda lame. Your mod revives it totally ))

@Sergey, in case you missed the BT mod : darekasan-net.hatenablog.com/entry/2021/08/23/184924 (use Chrome translate feature to read it in your language)

Hello, currently, when you plug the keyboard on the USB port, the keyboard does not switch on automatically (batteries present or not don't change anything). If you plug in the usb cord while the on button is pressed and stays pressed, the keyboard turns on and stays on (especially if you disable the "auto power-off" feature). The on/off push is a direct push (not a multiplexed push). Pressing the push means put a wire on the ground. Therefore if you short-circuit the related wires on the right connector, it might work as expected. The connector is "CB301", and pins are n°3 (Gnd) and n°4 (goes to an input on the micro-controler). FYI, pin n°1 is the coloured wire on the left. Having these pins shorted permanently shall not affect the HW durability. About the SW, I don't know how it behaves if this signal is LOW permanently. Kind Regards.

Correct, no change and no difference with the internal speaker. But about the jack output there's a major difference : normally, the pss series provides sound on both left and right, BUT the audio signal IS EXACTLY the same on both. It means the signal is biaural (twice the left channel in your headphones) but not stereo. My mod brings the real right channel from the sound generator to the jack. With this mod, the sound is now real stereo, because the audio that comes out of the sound generator is not exactly the same on left and on right channel.

@@LionelN Thanks for the response. So it is a dual mono solution in factory state?

@@elistvan correct, that's it. Hope you could hear the difference when watching this youtube video (with headphones, the difference is clear).

I was also hoping that there is enough room in there for a rechargeable battery and BMS circuit, that would be really cool

Hi, thank you for your comment. In my very first video about this topic (ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-cwDBfVab3vc.htmlsi=fxfCHokF3GXue6Zq) one guy commented his work about a modification to add some li-ion bat ( @sathish6601 ). If I remember well he also drop a comment on my blog) To get a line level line, just know that the volume level is changing depending on the user settings (vol+ vol- keys). No way to change this since the level is not a fix value at the SWLL chip output, it depends on the volume set by the user.

@@LionelN thank you!