11. Electronics & Wiring
DANGER!
Electric shock risk
Electricity can be fatal and you should be
qualified and confident to carry out any electric work.
!! VERY IMPORTANT !!
ALWAYS connect/disconnect wires and driver modules when power OFF
Voltage surge/spike can easily damage uncertain part of components, with a clear pop sound or silently. You'll cry!
Check wire polarity at BOTH board side and device side before power ON
Wrong wire polarity might result in short circuit and damage your device too.
Don't leave bare wires or electronic devices dangling
A careless touch might result in short circuit too.
Be very careful if you need to probe pins when power ON
Your probe might touch multiple pins at the same time and results in short circuit.
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.
Line-Powered Devices
Line-powered devices are located under the printer for safety reason.
Power Supply Unit
RH bolt m4 x 10 (4)
Washer m4 x 9 x 0.8 (8)
Two washers as spacers to shorten each bolt are must to prevent bolt from touching the PCB inside the PSU.
Terminal block
Bus bar (2)
RH bolt m4 x 10 (2)
Nut m4 (2)
Busbar (2)
Must leave a gap larger than 1mm between the two bus bars.
Fuse box
RH bolt m4 x 10 (1)
Nut m4 (1)
Install the fuse box without its white base.
SSR for bed heater
RH bolt m4 x 10 (1)
Nut m4 (1)
PTC chamber heater
RH bolt m4 x 10 (8)
Nut m4 (8)
DC-Powered Devices
DC-powered devices are attached at the back panel outside the printer for easier access.
Power switch
Bolt m3 x 10 (2)
Nut m3 (2)
Printed cap (1) (STL here)
Control board
Bolt m3 x 15 (4)
Washer m3 x 8 x 0.8 (8)
Nut m3 (12) (8 are used as spacers between board and ACM panel)
SSR for PTC heater
RH bolt m4 x 10 (1)
Nut m4 (1)
Chamber Fan
(Unused. Design a pipe adaptor if you want to exhaust chamber air to the outdoor, or seal it.)
Bolt m4 x 25 (4)
Nut m4 (4)
Customized Wire Statistics
Terminal Block
Busbar (2)
Action
Cut the 2 busbar pieces and attach them to the terminal block.
The terminal numbers 1 ~ 6 from left to right will be used later.
Power Socket Switch
Power socket switch
Terminal block with 2 busbars installed
Power Supply Unit
10cm, 16AWG, red wire, U-U terminals (1)
10cm, 16AWG, black wire, U-U (1)
10cm, 16AWG, yellow-green wire, U-U (1)
Bolt m4 x 10 (1 for GND wire)
Nut m4 (1 for GND wire)
Power supply unit
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!
Actions
Before connecting other electronic components, test the power supply unit independently first.
Make sure you have chosen the AC voltage in the PSU suitable for your country.
Connect the red, black and blue wires of the power socket to L, N, and ⏚ (ground) terminals on the PSU.
Connect the 10cm grounding wire to the frame using a RH bolt m4 x 10. In case that the grounding wire is not long enough in some versions, please connect it to the bottom of the Z frame.
Turn the switch ON and see if the indicator is lit. The fan will turn only when temperature condition is met.
If you have a multi-meter, verify voltages of each terminal.
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.
AC-powered Bed Heater
Bed heater power
10cm, 16AWG, red wire, U-U (2)
Bed control signal
25cm, 20AWG, red wire, U-pin (1)
25cm, 20AWG, black wire, U-pin (1)
Bed heater power:
Bed control signal:
PTC Chamber Heater
PTC heater power
45cm, 16AWG, red wire, U-U (1)
PTC heater control signal
25cm, 20AWG, red wire, U-pin (1)
25cm, 20AWG, black wire, U-pin (1)
Control Board:
BigTreeTech Octopus Pro
BigTreeTech Octopus Pro
10cm, 16AWG, red wire, U-U (2)
10cm, 16AWG, black wire, U-U (2)
30cm, 16AWG, red wire, U-U (1)
30cm, 16AWG, black wire, U-U (1)
Exam
Make sure the wire polarities are correct!
Endstop sockets
Fan sockets
Bed heater signal
Actions
Make sure all driver modules are inserted in the correct direction, module pins are all in the sockets, and 14 jumper caps are in correct positions.
The polarity of endstop sockets & fan sockets in GTR are different from usual endstop and fan wirings. Please swap the red wire (V) and the white wire (signal) at the board side.
The colors could be different, but align and insert the colored row of pinouts on the driver module or the S42C adaptor to the colored row of sockets on the control board.
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.
Control Board:
BigTreeTech GTR
BigTreeTech GTR
Exam
Make sure the wire polarities are correct!
Endstop sockets
Fan sockets
Bed heater signal
Actions
Make sure all driver modules are inserted in the correct direction, and 9 jumper caps are in correct positions.
The polarity of endstop sockets & fan sockets in GTR are different from usual endstop and fan wirings. Please swap the red wire (V) and the white wire (signal) at the board side.
The polarity bed heater signal (labeled as hot bed on the PCB) is opposite from other nearby power terminals.
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.
Inductive ABL sensor
Connect the wires using the heat shrinks or the customized pins 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.
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.
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.
ALL DONE?
Here is a checklist for you to prevent something wrong
Please print it out and check each items 1-by-1 😉