MiniRambo

Mini-Rambo versions: 1.1b, 1.3a

Summary

This board is based off RAMBo, the Arduino MEGA design, and the work of RepRap community. It has 4 stepper drivers and 4 mosfet switched outputs.

Differences from Rambo

MiniRambo has:

• 4 stepper drivers vs. 5
• 3 Thermistor jacks vs. 4
• 4 total mosfets vs. 6
• PWM control of stepper current vs Digital Trimpot
• Can connect RepRapDiscount LCD cables directly without an adapter board. (v1.3a+)
• Less general purpose IO connectors than Rambo.

Powering Mini-Rambo

MiniRambo you must connect power to the Primary Power input for RAMBo to operate. The USB connection is isolated from the rest of the board and cannot be a power source.

Features

Logic

• Arduino MEGA compatible Atmega2560 and Atmega32u2 processors are compatible with all RAMPS class firmware
• Crystals for both usb and mcu (timing accurate to 10ppm)
• 3 Thermistor jacks

Motor Drivers

• 4 A4982 1/16th microstep motor drivers(2 connectors on Z for Prusa Mendel and other dual Z printer designs)
• PWM Outputs for (XY), Z, E0 stepper current control instead of digital trimpot.

• Current limit on driver IC VCC to prevent permanent latchup
• Microstep mode configured by MCU through firmware (no jumpers needed)
• Test points for driver control signals
• Step and Direction pins are on their own ports for synchronous movement capability

PWM DC outputs (Extruders, Fans, Etc.)

• 4 outputs (1 Extruder, 1 BED, 2 low power (fan,etc)
• Low resistance mosfets for cool running
• Indicator led for each channel

Power

• 2 power input rails
  • Heated Bed, 15A 12-35V
  • Primary Power 10A 12-28V: Motors (5A dedicated fuse) + Extruders, Fans, & Logic (5A dedicated fuse)
• Built in SMPS for 5V generation from Extruders + fans and logic

PCB

• 4 layer
• 2oz copper on all layers
• High quality, High temperature FR4-TG130 PCB
• Gold ENIG finishing

Schematic

https://github.com/johnnyr/Mini-Rambo/blob/master/board/Project%20Outputs%20for%20Mini-Rambo/Mini-Rambo.PDF

Fuses

MiniRambo has 3 user replaceable ATO fuses (the type found in many automotives).

• F1 5A supplies the motors.
• F2 5A supplies the extruder heater + fan outputs and logic.
• F3 15A supplies the heated bed output.
  

Firmware

https://github.com/tonokip/Marlin/tree/1.0.2-TRP

Troubleshooting

This is a generic troubleshooting guide for RAMBo. These steps may vary depending on manufacturer configuration. Contact your supplier if these steps do not help.

• Cannot connect with 3D printing control software
  • Is the power indicator LED on?
    • Make sure the power is connected as described in :Powering Mini-Rambo.
    • Is a fuse blown? MiniRambo fuses
  • Is correct driver installed? RAMBo USB driver
  • Is there firmware installed on your RAMBo? Rambo firmware