BOSS SD-2 Dual Overdrive "orange" channel

[Voltron]

Hello. Can anyone please explain me why pluggin an expression pedal on the remote jack gives you an "extra channel" on this pedal?

It uses a latching type footswitch so i guess tossing a wiper pot there kida makes sense but, even with jfet switching??

ALso the change on LED indicator color is my confuse.

I'll post the googled schematic later, I don't know how to auto scale images here so I'll have to rescale and reupload. Try a googling it meanwhile 

[Steben]

I think it controls the voltage to the FETs, making them more like "mixing pots" to blend the channels.

[slacker]

If the LED is a red/green one and it turns orange then it either means both red and green are on at once or it's switching between them faster than you can see. So possibly the resistance of the expression pedal is causing the switching system to turn both channels on at once.

[Voltron]

http://www.aronnelson.com/gallery/main.php/v/KHE/Boss_SD2_schematic.jpg

Its a CMOS logic switching design

Uses a TC4011BP, a buffered CD4000 type 4in NAND gate.

The schematic shows 2 leds, so I thinks yes, means both channels are on at the same time.

Logic chip operation makes it a bit harder to see but seems like you can bypass one gate while on "remote" position by adding a resistor to ground on the remote input path. But I am still not exactly sure how this happens.