3mm LEDs, preferably bright ones. 64x LEDs for modulation matrix, 48x other CS LEDs on control surface, 1x LED for power on (mounts above power switch). Since all LEDs are in a 16×8 LED matrix, it is not advised to use different colours of LEDs that are powered by the same DOUT pin (through the same resistor) as the brightness will be different. See
mb-6582_cs_dout_wiring.pdf for LED wiring on the control surface. For example, if “SID 1” LED was red and “LFO 4” LED was green, most likely “SID 1” LED would be much brighter, since red LEDs are typically much brighter than green, on top of having a smaller voltage drop (so even a red and green with identical mcd value would have different brightness because they would receive different current due to different voltage drops across the current limiting resistor on the DOUT). However, you can use different LEDs in the mod matrix to the rest, as these use their own DOUT which is not shared with the other LEDs, so you are able to use different resistors in that DOUT to compensate for the different voltage drop. i.e. you can use red in the mod matrix, green elsewhere, and use higher resistor values before JD6 than the ones before JD7