20W RGB LED Driver Board Assembly (WS2811 version)

BOM

QTY    Part               Description
3      IC1,IC2,IC3        PT4115 constant current buck driver (soldered)
1      IC4                78L05 LDO
1      IC5                WS2811 (soldered)
3      L1,L2,L3           100uH inductor, 6x8mm, 500ma
3      T1,T2,T3           2N3904 transistor           
3      D1,D2,D3           1N5819 diode
3      R1,R2,R3           0.33R  resistor
3      R4,R5,R6           10K resistor
3      R7,R8              33R resistor
1      C1                 47uF/50V capacitor
1      C2                 0.1uF capacitor

Solder resistors

Use as little solder as possible.

Cut leads

Cut leads as close to PCB as possible.

Solder diodes

Pay attention to polarity, diode's cathode (stripe) should be on the left side of PCB, pointing towards the LED.

Solder monolithic capacitor, transistors, and LDO

Check markings on components, 78L05 is LDO (IC4,) 3904 are transistors. LDO and transistors should be soldered about 0.1" from PCB, total height should be ~0.3".

Solder electrolytic capacitor

Use PCB to bend capacitor's leads. Pay attention to polarity.

"-" lead should be facing 33R resistors.

Solder inductors

Inductors should be as close as possible to PCB. Apply pressure when soldering, heat for ~2-3 seconds, 2-3 times each lead.

Some inductors may have isolation sticking out on the bottom, trim if that's the case.

IMPORTANT: newer 20W cases have smaller dimensions and inductors will not fit vertically. If that's the case, mount inductors horizontally.

Prepare LED

Cut LED's leads as shown, try to keep them as long as possible (3 inner leads.)

Solder LED

LED should be mounted on the bottom. Use a lot of solder (and flood vias) to make pads stronger.

Pay attention to polarity and alignment. LED's anode should be close to 0.33R resistors (bottom side on the image.) "+" sign should be facing PCB (don't ask, markings are weird on those things :) .)