HeaterMeter 4.3 Base Board Assembly
The PCB may arrive with some scrap material around the edges where it has been de-panelized from other boards in the batch. In a few places, this excess material can cause clearance issues with the case so it is best to remove them prior to assembly.
To remove the excess, simply snap off any of the larger bits with a pair of pliers then file or sand the edge lightly to smooth the area flat. An X-Acto knife or razor can also be used. The board material is pretty soft so this shouldn't take more than a few seconds.
Do this to all four edges of the board to prevent any issues down the road. Once the components are installed it is difficult to trim these bits without damaging the hardware.
The HeaterMeter v4.3 PCB has two sides but components only go on one side. The silkscreen outlines indicate the component footprints where they should placed, which is on the underside of the board (the side opposite the "HeaterMeter v4.3.3" text and boxy robot logo). The easiest way to assemble the board is to start with the flattest components and work your way to the larger pieces.
| Qty | Value | Device | Parts |
|---|---|---|---|
| 3 | 1k | R-US_0204/7 | R1, R3, R21 |
| 1 | 2k2 | R-US_0204/7 | R14 |
| 1 | 10k 1% | R-US_0207/7 | R20 |
| 1 | 22k | R-US_0204/7 | R4 |
| 1 | 68k | R-US_0204/7 | R13 |
| 1 | 100k | R-US_0204/7 | R19 |
Step 1 Horizontally-mounted resistors. The orientation on these does not matter-- either lead can go in either hole, as long as the body of the resistor is on the right side of the board. The placements are sized such that you should be able to fold the leads of the resistor against the body at a right angle and have them just fit into the holes. It is fastest to insert a couple resistors at a time and flip the whole board over, resting the board on the resistors to hold them in place while you solder them and clip the extra leads off. You will have 4x 100k resistors and 4x 10k resistors left over to be used later.
| Qty | Value | Device | Parts |
|---|---|---|---|
| 8 | 0.1u | C-US025-025X050 | C1, C2, C3, C7, C15, C16, C17, C18 |
Step 2 Ceramic capacitors. These are small yellow blobs and also have no polarity, so their orientation does not matter. There isn't enough room adjacent to the capacitors in the block nearest the ATmega382P to put a label on each one, so be sure to populate each of the footprints in the "0.1u" block with a capacitor in addition to the three fully-labeled footprints (8 total placements).
| Qty | Value | Device | Parts |
|---|---|---|---|
| 2 | 1N5819 | 1N5819 | D2, D3 |
Step 3 Diodes. The rectifier diodes have a white line on them to indicate their polarity and should be installed so their white line matches the white line marking on the PCB. Both diodes are identical, either diode can go in either footprint.
| Qty | Value | Device | Parts |
|---|---|---|---|
| 1 | FQU11P06TU | MOSFET-P | Q3 |
| 1 | DIP28 | DIP28 | IC2-SOCK |
| 1 | PCC-SMP | PCC-SMP-K | J4 |
| 1 | ALARM | SPEAKER/AL11P | SP1 |
Step 4 Install these parts in the order listed above. The power MOSFET Q3's leads can be easily formed to the right dimensions by simply inserting it into its hole then bending it down into position. Soldering the tab of the MOSFET to the PCB is not required for the standard blower. Then, install the 28 pin DIP socket for the microcontroller. The socket has a notch on one side which indicates the direction it needs to be placed which matches the silkscreen on the footprint. Do not install the ATmega328P chip into socket IC2 at this time. If assembling a HeaterMeter with a thermocouple, install the thermocouple jack and copper support strap. The alarm speaker can then be installed in any orientation.
| Qty | Value | Device | Parts |
|---|---|---|---|
| 3 | BS170 | BS170 | Q1, Q2, Q5 |
| 1 | MCP1700-33 | MCP1700-33 | IC4 |
Step 5 Signal MOSFETs and 3.3V regulator. These are the pieces that look like tiny black water towers with 3 legs. Bend the center lead back at a right angle to the body and then bend it down using your needle nose pliers. The flat front of these devices should be matched to the flat front on the silkscreen of the PCB.
| Qty | Value | Device | Parts |
|---|---|---|---|
| 1 | OKI-78SR-5 | OKI-78SR-05H | IC1 |
| 1 | Pi | PINHD-2X13 | JP1 |
| 1 | 16MHz | RESONATORRESONATOR-PTH | Y1 |
Step 6 Again install these components in the listed order. The 5V regulator sub-board, 26 pin RaspberryPi connector, and the larger 3 pin orange blob 16MHz resonator. The orientation only matters on the 5V regulator. The Pi connector is placed on the same side as all the other components (where the silkscreen outline for it is)-- installing it on the solder side is a real super-happy-fun-party to try and correct.
| Qty | Value | Device | Parts |
|---|---|---|---|
| 4 | 10k 1% | R-US_0207 | R5, R16, R17, R18 |
| 4 | 100k | R-US_0204 | R22, R23, R28, R29 |
Step 7 The leftover resistors from step 1 are installed now for each of the probe jacks. There isn't enough room on the PCB for the silkscreen for all the 100k resistors, so again populate all the resistors in the 100k block. Do not install 10k resistor R18 in the pit jack if using a thermocouple.
| Qty | Value | Device | Parts |
|---|---|---|---|
| 1 | 220u | INDUCTOR9MM | L1 |
| 1 | 100u/25 | CPOL-USE2.5-6 | C4 |
| 2 | 100u/10 | CPOL-USE2.5-5 | C5, C6 |
| 1 | 47u/25 | CPOL-USE2.5-5 | C12 |
Step 8 Power inductor and electrolytic capacitors. The inductor has no polarity, insert it in a haphazard manner. The capacitor "cans" have a line going down the side which indicates the negative side, the PCB has a teeny plus symbol to indicate the positive side. Use deductive reasoning to ascertain the correct orientation. I know one of the 100u/10V capacitor's teeny plus symbol is hard to see. I am sorry! It slipped under the radar before the release boards were made. It installs in an opposite orientation than the other 3 capacitors.
| Qty | Value | Device | Parts |
|---|---|---|---|
| 1 | POW | POWER_JACKPTH | J9 |
| 1-4 | Probes | AUDIO-MONO | JP3, JP4, JP5, JP6 |
| 1 | RJ45-8 | RJ45-8 | JP2 |
Step 9 Rounding out the bottom-side assembly are the remaining I/O jacks. You're in the home stretch now. Do not install JP3 if creating a thermocouple variant.
The HeaterMeter base board is now complete. The board can be tested by installing the ATmega chip into the socket, attaching it to the Raspberry Pi and booting it, or continue to the HeaterMeter 4.3 LCD/Buttton Board Assembly.