Behringer BXL 1800A

[Enzo]

it is an analog multiplexer, think "switch." You can use a member of the 405x series as a routing switch. Good for channel switching or turning reverb off and on. Look on your BX1200 drawing over left of tone stack and right of SHAPE, feeding into IC10a, see what appears to be a switch which says GAIN above it? That is two internal sections of the 4053 used as a SPDT. And another down by ULTRABASS switches that feature.

4013 would be used in the control part of channel switching.

isn't the +5 powering the 4013?

[diydidi]

I see the BX1200 drawing. It has these exact same circuitry as the BX in that switching section, BUT, it also has these two added IC's 4013 and 4053.
I cant tell what voltage rail should be powering it. No continuity from any of the rails to the supply pins of these two chips (pin14).
Only a schematic will tell. Someone on here should have a schematic surely?