• Check Wire Polarities

The endstop wire polarities of BigTreeTech and Mellow are different. Please swap the wires if necessary.

Check the terminals

Some of the terminals are connected by the clamping force of the terminal itself. Please double check that they are firmly connected. 

If you plan to solder the terminals, cover the joint with enough solder to lower the electrical resistance and possible heat generated. Common solder has a melting temperature 180~240°C which is higher than the wire sheath. Avoid use low temperature (100~130°C) solder.

Attach components

Power socket

• Bolt M3 x 08 (x2)

• Nut M3 (x2)

• Washer M3 x 8 x 0.8 (x2, inner side)

Power supply unit

• Round head bolt M4 x 8 RH (x4)

Solid state relay

• Round head bolt M4 x 12 (x2)

• Nuts M4 (x2)

Fuse box

• Bolts M4 x 8 RH (x2)

• Nut M4 (x2)

Driver cooling fan & duct

(For Mellow FLY CDY board only)

• Bolt M3 x 16 (x4)

• Nut M3 (x4)

• Washer M3 x 8 x 0.8 (x4)

Power Socket Bracket — Power Supply Unit

Actions

Before connecting other electronic components, test the power supply unit independently first.

1. Make sure you have chosen the AC voltage in the PSU suitable for your country.

2. Connect the red, black and blue wires of the power socket to L, N, and ⏚ (ground) terminals on the PSU.

3. Connect the 5cm grounding wire to the frame

4. Turn the switch ON and see if the indicator is lit. The fan will turn only when temperature condition is met.

5. If you have a multi-meter, verify voltages of each terminal.

Connect the grounding wire to the frame. If your frame is black, grind the black layer off so the wire contacts with bare aluminum material.

Under normal condition there is NO electricity at the grounding wire and frame. The grounding wire provides a bypass path in short circuit condition and prevent you from electric shock.

If an abnormal short circuit condition happens, the circuit breaker in your house breaks and stops providing electricity immediately.

Exams

Double confirm the connectors both at the switch side and PSU side are FIRMLY CONNECTED. Heat will accumulate at a loose contact point, melt surrounding plastics and cause short-circuit!

AC-powered bed heater

Attach Control board

• Control board

• Bolt m3 x 16 (x4)

• Nut m3 (x12)

• Washer m3 x 8 x 0.8 (x4)

Actions

Attach the board onto back panel. Be very careful not to knock off nearby electronic components.

[BigTreeTech] Octopus Pro

Follow the picture and  make sure all driver modules are inserted in the correct direction, and jumper caps are in correct positions.

Note that the inductive sensor at Z-min endstop slot acts as both Z-min endstop and ABL sensor. So you don't need a printed Z endstop mount nor a trigger finger.

Important notes:

The polarity of GTR endstop sockets & fan sockets are different from usual endstop and fan wirings. Please swap the red wire (V) and the white wire (signal) at the board side.

[BigTreeTech] GTR

Follow the picture depending on the type of XY steppers included in your kit,  make sure all driver modules are inserted in the correct direction, and jumper caps are in correct positions.

The bed control signal wires are connected to the heater port 1 of GTR, which is labeled as "bed heater" in the picture. The HOT_BED_OUT and BED_POW_IN marked on the board are not used.

Note that the inductive sensor at Z-min endstop slot acts as both Z-min endstop and ABL sensor. So you don't need a printed Z endstop mount nor a trigger finger.

Important notes:

The polarity of GTR endstop sockets & fan sockets are different from usual endstop and fan wirings. Please swap the red wire (V) and the white wire (signal) at the board side.

[Mellow] Fly CDY

Check the v2 or v3 control board pictures in the next page. Make sure all driver modules are inserted in the correct direction, and wire polarities are correct in endstop and fan sockets.

Two schemes are for the Z endstop and the A scheme is used as default in RRF config.g. If you prefer scheme B, just insert the cable as shown in the picture and uncomment related commands in RRF configuration files.

• Scheme <A>
  The inductive sensor at Z-min endstop slot acts as both Z-min endstop and ABL sensor. So you don't need a printed Z endstop mount nor a trigger finger.

• Scheme <B>
  An optical endstop sensor acts as Z-min endstop and the inductive sensor at Z-max endstop slot acts as ABL sensor.

Inductive ABL sensor

The inductive sensor acts as the Z endstop.

Connect the wires as shown in the picture. Sometimes the color sequence change in different batches, just match the wires based on color and tape them from falling apart.

Plug the ABL sensor to the Z endstop endstop. The polarity of endstop sockets in BigTreeTech board and Mellow board are different. Please follow the according pictures.

The LED on the sensor should light up when no metal object is nearby, and dims while being triggered.

(For Group 1 and before only)
Move red and black wires from the XH2.54 4p male connector to the XH2.54 3p male connector, as shown in the picture. The 4p connector is a redundant component.

5V peripherals

Must be sure the polarity is correct when you're inserting 5V peripherals:

• Endstops

• Fans

• ABL sensor

• Filament sensor

• Your newly added peripherals

A wrong polarity might damage major chips (WIFI, driver, power, etc) on the Mellow Fly CDY v2 board. The picture shows the wires that polarity has to be aligned.

[For Mellow Fly CDY only] Two schemes are for the Z endstop and the A scheme is used as default in RRF config.g. If you prefer scheme B, just insert the cable as shown in the picture and uncomment related commands in RRF configuration files.

• Scheme <A>
  The inductive sensor at Z-min endstop slot acts as both Z-min endstop and ABL sensor.

• Scheme <B>
  An optical endstop sensor acts as Z-min endstop and the inductive sensor at Z-max endstop slot acts as ABL sensor.

Exam

For Mellow Fly CDY, Make sure 9 blue jumper caps are in correct positions as shown in the picture. One of them selects the power source, 5V or 24V, for the endstop slots. If it is not capped, optical endstops won't work.

Debug with a multimeter

Be VERY careful if you are probing nearby pins. A careless short circuit might damage unknown parts of the main board and result in unexpected behavior.

Filament sensor (Type A)

DO NOT insert this filament sensor to the control board because the V/G/S character shown in the picture and the functionality does not match. SecKit has stopped including this sensor as it confuses builders and might burn the board.

If you already have such sensor, use it on your own risk and only after you fully test it in an independent environment out of the main board, and know the characteristics of this sensor.

----

The wire polarity of filament sensor might be different batch by batch. To prevent short-circuit and a burnt board you MUST open the sensor case with a small flat head driver from side of the case and make sure wire polarity is correct before inserting it to the main board.

Here 2 kinds of PCB layouts are listed for your reference.

Filament sensor (Type B)

SecKit has stopped including this sensor as it confuses builders and might burn the board.

DO NOT use this filament sensor. If you already have such sensor, use it on your own risk and only after you fully test it in an independent environment out of the main board, and know the characteristics of this sensor.