Step 1 – Resistors

Fit three resistors of 470 Ω at R3, R6, and R8 (yellow/violet/black/black/brown). For Round 3 these may be 510Ω (green,brown,black,black,brown). [these are the LED resistors] – Resistors are not polarised components.

Step 2

Fit one resistor of 4.7kΩ at R7 (yellow/violet/black/brown/brown) [this is the MOSFET base resistor]

Step 3 – Large Resistors

Fit the four large (220 mΩ) resistors at R1, R2, R4 and R5 (red/red/silver/gold/black with a green background). Check that you use the correct holes, as there is a test point hole close to the R2 left leg position.

Step 4 – Small capacitors

Fit two brown (tan) 100 pF capacitors (marked "101") at C1 and C5 [these are to set the chopper frequency on the steppers]. The markings for C1 could cause confusion – refer to the picture for correct placement. Check the values carefully: there are 3 different small capacitor values, 22, 101 and 474, all in similar packages. The value is marked in tiny writing on the component. These are not polarised components.

Step 5

Fit four blue 100nf capacitors marked "104" (some of these may instead be marked as "474" but can be used interchangeably) at C2, C3, C6 and C7 [decoupling caps].

Step 6

Fit the black diode in the centre bottom of the board above the trio of resistors. [Protection diode for MOSFET].

This component is polarised and must be fitted with the silver band to the right, aligning with the black strip in the board markings.

Step 7 – LEDs

Fit the two square yellow cased LEDs to LD1 and LD2 at the bottom of the board. Make sure these are upright and leave maximum room for fitting the adjacent 8 pin header later

These components are polarised and must be fitted with the positive (i.e. longer) leg to the top hole, marked + on the board or they will not light. The short leg is normally the cathode (negative) leg, and the long leg the anode (positive) one.

You can confirm this using the diode or LED setting on a multimeter (if you have access to such an up-market meter) or by using a resistor and a power source. (more info needed about how to do this)

LED Info on Wikipedia

Step 8

Fit one red-cased LED (small red rectangle with a dome) in the centre of the trio of resistors at the bottom of the board, remembering that + is the long leg and goes into the right-hand hole. The marking on the board is partially hidden at this point by the resistor

This component is polarised The short leg is normally the cathode (negative) leg, and the long leg the anode (positive) one. See note in step 7 above

Step 9

Fit three connectors at the bottom of the board, the 2-pin connector in the centre, and the two 4-pin connectors to left and right [one for each stepper motor]. Take care that they stay aligned flat to the board as you solder them in. The Blu-Tack tip is particularly helpful here.

Do not overheat, as you can melt the plastic with thermal conductance from the large pins. Tack each connector into place at each corner pin first and and then you can ensure a good amount of solder is applied, as these connectors are demanding both mechanically and electrically.

Step 10 ‐ Skip This Step

Optional step - not recommended, can be added later if needed: here we can fit two test pins either side of the C4 capacitor marking. These are used to provide a place to get a trigger signal for an oscilloscope when testing the chopper decay. There is a place for a third pin as GND, but is is very close to the large resistor and so is not being fitted. There are many alternative GND points on the board that are easier to connect to anyway. These single pins can be very fiddly to solder, so the choice is yours. In further pictures they are not shown, and this pic is from v1.0 and provided for reference to the pin position only

Step 11

Fit the two 8-pin headers, JP1 and JP2. [for jumpers to set decay & step sizes] These are not handed, and can go either way around, so long as the long pins face up from the board.

Do not overheat, as you can melt the plastic with thermal conductance from the large pins. Tack each connector into place at each corner pin first and and then you can ensure a good amount of solder is applied, as these connectors are demanding mechanically. Make sure these headers are mounted flush to the board so they don't lean.

Note that these headers may have been created by chopping off from a longer length, so the ends may not be very square and neat. In particular one of the headers is rather close to the yellow LED 1, so consider whether you need to file or cut your header to trim it so it fits ok.

Step 12

Fit the two 4-pin headers JP3 and JP4. They are not handed and can go either way around, so long as the long pins face up from the board. Make sure these headers are mounted flush to the board so they don't lean. As above, be careful with overheating.

Step 13

Fit gold coloured tantalum capacitor 22μF at top left C8. For Round 3 boards these may be 33μF

Caution: this component is polarised and must be installed correctly, otherwise it can explode in a dramatic and hazardous way. The positive (+) hole is marked (but note that the printing will be under the 8-pin header by now) – it is the one furthest from the edge. The capacitor's positive leg is marked with a + sign. Good eyes are needed to see this, but it is normally the long leg. You may also need to bend the capacitor's legs slightly to allow access to the jumper header. Take care not to bend too near to the capacitor body as it is quite fragile. It does not need to be pressed tight to the board, so you can leave some leg for the bend.

Step 14

Fit right angled black boxed header [link to controller board]

Note: the design allows for a wider 14-pin connector with extended functionality. The TVRR reference build uses a narrower 10-pin header that fits in the centre of the hole array. Tack the corners first and ensure each pin has a good amount of solder applied to anchor the header to the board.

Step 15

Fit the 2-pin screw terminal block facing up/outward. It will take extra solder to make a strong joint. This component will be subject to mechanical stress when in use

Step 16

Fit the large black 220 μF electrolytic capacitor at C4.

This component is polarised. The negative (-) end is marked by an arrow with a - sign, and usually the can has a 'neck' at the positive (+) end. The graphic on the board is larger than the component and to ease the fitting of the final component (the PTC fuse in step 19) we found that we could adjust the legs to bias the fitting to toward the negative end (see pic for alignment)

Step 17

Static care: Now to fit the most important components! The two stepper drivers are large and, like a millipede, have many legs. Hopefully yours are all in line and straight. If not, now is the time to align the legs.

Apart from the number of legs, they should be straightforward to fit. Ensure they a vertical, this is important for mounting to a heatsink later. Making good joints and the using the right amount of solder is important. Too much solder may cause shorts on either side of the board; not enough may cause 'dry joints' after extended use. They are not difficult to fit – just check the joints with a magnifier on both sides of the joints.

Step 18

Static care: Fit the MOSFET (STP55N or P55NF06L). For some Round 3 boards these are substituted by NTD4963N-1G (if you have 3 of these in your pack), which has a much smaller heatsink tang at the top. The board silkscreen depicts the orientation by a black bar representing the metal heat-sink that should point upward. These chips need to be perfectly upright, and should easily sit in the position. Try to avoid soldering them in a leaning position.

Note: It is best to protect the MOSFET from static charges. In the pic we see a professional system, but touching an earthed pipe or metal PC case is an alternative.

Step 19

Fitting the last item on these boards, the PTC (solid state resettable fuse). This is a large and incongruous component that has given Al more grief that most of the others! It was a little tricky and ugly when previously mounted on the top of the board, thanks to Barnaby for suggesting that we fit underneath. The legs need to be bent to 90 degrees while being careful not to crack the PTC itself. Using some pointed pliers to protect the top of the leg during bending is a handy tip. Looking at the underside of the board, if the previous steps are all correct, there should be only two holes available in the top left, this component is not polarised. Do a test placement, check the legs protruding into the top side of the board, remove and then trim the legs of surplus length before soldering in place. One leg will be need to be trimmed shorter than the other.

The pic also shows the underside of the board before cleaning the flux off the board. If you look closely at the full sized pic, you can see why examining the board closely with a magnifier will pay dividends later :)

Step 20

At this stage you should do the electrical check on the boards, before adding the jumpers. Fit the jumpers to the places as shown in this photo. Please note that the board markings are inaccurate (as for the 1st Build Group) and you should, instead, trust this photo for jumper positioning.

Step 1

Fit four 4.7kΩ (4K7 yellow, violet, black, brown, brown) resistors at R1,R2, R3, R4. Leave the resistors raised a little above the board, this will allow you to 'ease' their position if needed when fitting adjacent components later.

Step 2

Fit 10kΩ (brown, black, black, red, brown) resistors at R5, R6, and R17. Leave the resistors raised a little above the board, this will allow you to 'ease' their position if needed when fitting adjacent components later.

Step 3

Fit three 100 kΩ (brown, black, black, orange, brown) resistors at R7, R12, and R20. Leave R20 a little raised above the board, you need to ensure the DIL Sockets to left and right of R20 can be mounted in a later step, and R20 may need to be 'eased'

Step 4

Fit the 1 kΩ (brown, black, black, brown, brown) resistors at R8, on the left-hand side, a little above halfway up the board and R13.

Beware of accidentally filling the adjacent IC leg hole.

Alternatively, before fitting R13, take part of step 24 out of order and fit the 40 pin socket. Tack the socket in place by soldering the (viewed from above) top right and bottom left pins (do pay attention to step 24's warning about ensuring all the pins of this socket are straight). That way, when fitting R13, you can solder both R13 and the adjacent pin of the socket.

Step 5

Fit a 220 Ω (red, red, black, black, brown) resistor at R15. Leave the resistors raised a little above the board, this will allow you to 'ease' their position if needed when fitting adjacent components later.

Step 6

Fit 470Ω (yellow,purple,black,black,brown) at R16 on the top right of the board. For Round 3 these may be 510Ω (green,brown,black,black,brown).

Step 7

Fit the diode – a small orange-coloured component at D1.

This component is polarised, and the black line goes to the top, matching the line on the board graphic.

Step 8

Fit black diode at D2.

This component is polarised, and the white line goes to the left, matching the line on the board graphic.

Step 9

Fit the beige inductor (red/red/brown/gold – 220 μH) in L1 on the left side of the board, a little over halfway up. It is not polarised.

Step 10

Fit tiny two honey coloured 22 pF capacitors at C1 and C2, to the right of the crystal position. Double check that you have the 22 pF ones. They are not polarised. NOTE (admg 2014-02-09): For Round 3 these are the same value but round, tan coloured capacitors.

Step 11

Fit the 20 MHz Crystal. Leave this raised a small amount above the board, as the case of the crystal should not touch any of the tracks or components near it. You may wish to use a small piece of thin cardboard as a spacer while you solder it. It is not polarised.

Step 12

Fit the rest of the 100nf (and/or 470nf if you have those instead) blue capacitors (10 in all, marked "104" or "474") at C6, C7, C8, C9, C10, C11, C14, C16, C17 and C20. These are not polarised.

Step 13

Fit the SD Card holder. It has bumps on its underside that should hold it in position through the two holes near the edge of the board. It should bump into position exactly; solder the two outside tabs first and then the inner and outer legs. All soldering is on the top for this surface-mount component.

NOTE: The 3 pins at the rear of the SD card socket (bottom right in pic), if you refer to the previous pic you will there are 3 pads, 2 of which are very close together. It is best to keep from bridging the pads with solder, though if you do so it will *NOT* cause problems because the signals on these pins, which are for the SD card detect 'write protect' function, are not used in this OMC variant.

Step 14

Fit the reset button, facing outward. Solder all four legs, the rear two are supports.

Step 15

Fit the smaller gold-coloured tantalum 1 μF capacitor at the top in the position marked C15 long leg to right. This component is polarised, so ensure that the positive (+) leg is nearest D2.

The markings on the board may be partially covered by the adjacent below printed line.

Step 16

Fit three 2-pin connectors and three 3-pin ones at the bottom of the board. [thermistor (2-pin) and endstop (3-pin) connectors]

Step 17

Fit the two six screw terminals at the top of the board. Facing outward.

Note that these components may have a notch at one end and a corresponding bump at the other. So they can be assembled into, effectively, a single 12 screw terminal before positioning on the board. If you fit one 6 screw terminal block and solder it into position, you may find it hard to fit the other afterwards.

Step 18

Fit the right-angled black-boxed 10-pin headers on the left side of the board [connections for cables to driver modules].

Step 19

Fit the green LED at PWR with its long lead (anode, +) to the left (adjacent to terminal block) and the shorter lead (cathode, GND, -) closest to outside edge. Located at right hand top corner.

Step 20

Fit the red LED (clear casing) at HB below reset switch with long leg (positive, +) to the outside (right)

Step 21

Fit the Voltage Regulator IC4 LP2950Z labelled 7CM151E KY5033 (or 'N99AC, 2950A, CZ3.3') at IC4 with the flat face towards the bottom of the board, as shown on the markings on the board.

Step 22

Fit the larger gold-coloured tantalum 22μF capacitor at C12 below IC4 with long leg to + mark on board. Observe the correct polarity (positive to the left). Note that the legs on this need to be carefully squeezed together to avoid putting pressure on the gold body part. NOTE (admg 2014-02-09): For Round 3 a 33μF tantalum capacitor was substituted.

Observe the correct polarity, as shown by the + sign on the board (positive/+ to the left). Note that the legs on this need to be carefully squeezed together to avoid putting pressure on the gold body part.

Step 23

Fit F1 PTC fuse at top of board below terminals above IC3 position.

Step 24

Fit the three DIL IC sockets. Your sockets may be marked with a notch or a square hole that aligns with the marking on the board, i.e. at the bottom for the large IC1 and at the top for the two small ones at IC2 and IC3.

Check closely, then double check *before* soldering to ensure all legs are protruding evenly through the holes on the back of the board. It is very easy to have one fold under the socket while fitting all the legs through, run a finger over the underside of the board to check you can feel all the legs. Once soldered the sockets are unlikely to be removed without damaging the pins. Tack the diagonal corner pins and check the socket is flat against the board before soldering the rest of the legs. Be quick, to avoid overheating any single pin, which risks melting the plastic socket

Step 25

Fit 3 10uf ceramic blue caps at c3,c4,c5 in bottom left, ignore the polarity marking

Step 26

Fit fuse holder F1 (4 pin) top right

Step 26a

Fit FTDI header at COM square and level

Step 27

Fit the three 10 μF ALU electrolytic capacitors (black cans) at C13, C18, C19.
These are polarised. For each can, double-check which leg is positive (should be marked on the case), and match it to the + marking on the board.

Step 28

Fit the one 2-pin jumper in the space marked J1 in top right

Step 29

Fit the SPI/ISP header at the bottom right. these are just plain pins now.

Step 30

Fit little MOSFET in Q4 NTD4963N-1G ( marked 'A28 49 63Ng') at top left by terminal. The heatsink faces outward (in line with bar line on board print). NOTE (admg 2014-02-09): For Round 3 there may be a substitute: 'A50 49 63Ng'.

Step 31

Fit 7805 in IC5 raising it up to clear socket for IC1. The heatsink faces down, away from the terminals.

Step 32

Fit P-MOSFET (IPP80P03P4L-04) in Q3 (marked '4P03L04 GAB144') noting the opposite orientation to 7805. These two conponents must not touch each other.

Step 33

Fit N-MOSFET (PI80N03S4L - identifiable as the one with low heatsink and circular mark in centre with '4N03L04 6AA816') in Q2 at top right with heatsink facing reset switch

Nearly Complete!

Final stage testing prior to inserting the chips. Insert the fuse before testing. Electronics Checks Procedure After conducting the un-powered tests, insert the chips.

Take the usual static precautions, and you will need to ease the pins to the vertical by resting the row of pins on a hard surface and gently pressing to align the pins. This is needed because such DIL chips have the pins 'splayed' slightly for use in an automatic placing machine. An alternative is to use a 'chip insertion tool' if you have one available.

Ensure that all the legs of each chip are in the socket correctly before pressing the chip home. It can happen that a leg misses the socket and gets bent outside.

You may wonder about the components that have NOT been fitted:
You can fit the four test pins, but we have found it easier to conduct tests without the pins fitted, and having 0v, 5v and 3.3v pins sticking up increases the risk of shorting them accidentally.
The two other header pin sets (2 at SDWP and 4 at top left) are not needed for TVRR use. (SDWP stands for SD card Write Protect.)