Hands-on Guide

D1, R1, SW1

• Resistor lead bending, insert into board and bend to hold in place

• LED polarity (silkscreen reminder), insert and bend to hold in place

• Show how SW1 will be difficult to hold in place

  • Slightly pre-bend the outer leads and show how SW1 becomes a press-fit

• Clamp board with pana-vise

• Position HDMI microscope about 6 inches above board

• Solder D1 and R1

  • Make sure the student can see what's happening on the TV

  • TA should be looking at the board on the bench, NOT the TV

  • Use through-hole technique from the online tutorial. Demonstrate adding a little solder, waiting a moment to see it wick into the through-hole, then adding a tad more

• Snip the leads. Show how to use other hand to hold the pin so it doesn't fly away. Set pins in a pile nearby on the bench for later use

• Reposition board to see SW1 pins, emphasize the importance of moving the board around as often as necessary to reach the area of interest

• Solder SW1

C1 (0.22uF)

• Reposition board to see C1 pads, reiterate the importance of moving the board around

• Tin the non-grounded pad of C1, mention how it's easier to solder pads with "fewer connections" (less thermal mass)

• Briefly mention tweezer sizes and etiquette, showing how large tweezers would prevent C1 from sitting flat on the board and bent tips would make it difficult to hold

• Slowly and carefully show how to slide the capacitor into place while heating the tinned pad

  • Mention these capacitors don't have a polarity

  • Use the technique from the online tutorial.

  • Remove iron THEN remove tweezers. Mention how "pressing down" on the capacitor can cause it to slip out and shoot across the board

Tin U1 pad

• Reiterate the thermal mass comment

U1 (5 volt regulator with "L53B" marking on chip)

• Smaller pins first, big terminal last

• Show how big terminal has larger thermal mass- needing more time/heat to get the solder to wet

C2 (0.1uF)

• Flip board over in pana-vise (open jaws to hold length-wise)

• Mention the importance of positioning (again). Show how it helps reach C2

• Tin C2 pad (mention thermal mass again) and solder C2

Prep. breadboard

• Show how to snip header pins

• Cut 2ea of 2x3 headers and insert into breadboard power rails (about 1/2 down the length of the breadboard)

• Place board on pins and use a single row of header pins placed on the side to prop board 

• Show the importance of having the board sit flat on the header pins

J2

• Reiterate the through-hole technique discussed for D1/R1

Waste and Cleanup

• Find the small pile of snipped pins from earlier and show how to properly dispose of them in the waste bin.

• Tin the iron and put back in the holder

D2, R6

C4 (0.22 uF)

• After the student solders one side of C4, ensure the capacitor is lying flat on the board before letting them proceed

U2 (3.3 volt regulator with "C3Q" marking on chip)

• The student will need to reposition the board the in pana-vise

• Make sure a pad is tinned and the student knows they can rotate the board whichever way gives them the best angle for soldering

• It's likely the student will struggle while soldering the large tab on the U2 regulator. If the student isn't able to achieve consistent wetting to the pad/tab after 2-3 tries, then it is an excellent opportunity for the instructor to introduce the concept of paste flux. 

  • Apply paste flux to the tab and have the student hold their iron horizontally such to make contact with the tab and the pad. Ensure they wait long enough to melt the solder and emphasize how the flux helped with conducting heat and removing the oxides.

R11, R12, R13, R14

• Having only been exposed to surface-mount capacitors, these resistors are for additional practice with 1206 components

• Mention that resistors have an "up" and a "down" orientation and that the black side (with markings) should be facing "up."

C5 (47 uF)

• The student will need to reposition the board again and they should be mindful not to hit the nearby LED with the iron

J3

• Have the student transition to the breadboard that already has the header pins in place

C3

C6