DSO 150: Converting old analog board to new layout ( part 3 : remove Vbias )

So now with have the ADC Bias driven by the -5v
So let's remove VBIAS altogether, we dont need it and it will lower the consumption by a few mA

I did it, and now coupling sel does not work anymore (AC/DC/GND selection)
Wtf ?

Ah, it so happens that VBIAS is used elsewhere :)



Gotcha, it is the power supply for the AC/DC/GND switch.
If we look at the new board layout, it is using 5v instead. The used pin is PA5.
Let's check the pins :

PA5 is not marked as 5v tolerant.
Ok, let's check the new board layout again.


Only protected by the 1k resistor. I guess that's ok, even if i dont like that much.

So let's  remove R28, R22 and D1, connect left pad of D1 or R22 to AV+, and we are back



All done on the analog board :)

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