g-man wrote:
So, if you only wanted to control the effects on/off and reverb on/off and not have the channel switching, you would measure the voltage at the "top" of R158 (labeled VAC on the schematic) and determine the resistor values needed to get these at TP40?
0.52 vdc (efx off, rev off)
3.13 vdc (efx on, rev off)
4.99 vdc (efx off, rev on)
7.45 vdc (efx on, rev on)
Well, I cannot say for certain. But, yes. That is how I'm reading the schematic.
And I would also assume that the MCU is wanting to see very precise voltages. As an armchair engineer, I would assume they programmed the MCU to recognize the various voltages created by the series diode array, rather than selecting very specific diodes and LEDs to produce extremely specific, yet arbitrary voltages. So if you're going to go that route, I'd suggest using trimpots rather than actual resistors. Then you don't have to calculate anything or worry about finding some odd ball precision resistor value. You can just dial in the trimpot till the amp selects the setting you want for that switch position.
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