sfcs ~ A-142 mods

Because of not being easily cyclable, the A-142 did not end up the 'krell base envelope' akin to the Music Easel's pulser i envisioned it to be. However, it ended up a very useful building block for percussive patches. The voltage control over decay comes in handy when controlled with keyboard velocity, and events can be timed with the included comparator. However, there's one strange thing to the design: it has a sixteen-pin header, which in Eurorack implies the need for external 5V power and/or compatibility with the A-100 CV/Gate bus system. In this case, neither are present. Not needing 5V for an analog envelope is understandable - that's usually for microcontrollers. But why can't it pick up the bus gate?! Because i am one of those rare cases that use the darn thing, so i may as well have all my envelopes fired from it, including this one! Inspired by the presence of a proper 16-pin header and absence of the bus gate normalling implementation, i set off to mod my A-142 so that it normals in the system bus gate if nothing is patched into its gate input jack.

	Start by carefully taking off the pots (using the butt end of some tweezers as a lever helps) and unscrewing the jacks and pots, put the nuts and panel aside. Now, desolder the topmost jack by carefully heating up the pads on either side and pulling it out little by little. After 4-6 motions you shoukd have it out. Be careful not to burn the pads! We can now see that the signal and normal legs of the jack are shorted underneath it, and the gate signal comes to the circuit from the normal leg's side, which means two cuts.
	First, cut under the jack as shown. This disconnects the actual signal pin (top) and the normal to which the bus gate will come (bottom) apart. Now the circuit's gate input is from the normal pin only, which is still incorrect, but already better.
	The trace from the gate jack normal pin to the circuit's gate input is quite long, and there's a convenient place to cut it as shown. After cutting it, prepare two thin insulated wires with stripped and tinned ends, about 7cm each.
	Time to restore the connections! Solder the 3.5mm jack back in. From the upper two pins of the power/bus header, rotue to the bottom-facing normal pin of the jack. From the pin which was routed to the normal pin before and is now cut off (the one in the middle of the PCB), run a wire to the top-facing signal pin of the jack. Now if nothing is plugged in, the normal leg gets shorted to the signal leg, and if external gate is patched in, the connection is broken. Tadaa!