Delta 2040 Turbo by WASP

Actually unsure whether it’s a Delta 2040 Turbo or a Delta 2040 Turbo2 or a plain Delta 2040.

It probably is not a Delta 2040 Turbo since those came with an Arduino Mega 2560, while ours originally had a custom proprietary board with an Atmega SAM8x3, same as Arduino Due, and an ESP32 for what the company reports to be OTA firmware updates.

Microcontroller suddenly unable to driver the E0 motor driver, looking with an oscilloscope no signal would come out of the pin itself. Deemed broken, we noticed the board had a populated motor driver circuit for a secondary extruder which was unused by our single-extruder printer. We asked the company for the firmware (which appeared based on Marlin 1.x) so that we could change but they refused saying that “it is proprietary”, which of course we did not believe. If we are right, and the firmware is really based on Marlin 1.x as they mentioned in a phone call, they are not respecting GPLv3, which is the license MarlinFirware is released under.

Later changed the original board for an BTT SKR E3 Mini V3.0, with a Zonestar LCD.

The Zonestar LCD requires some wiring change, which I should provide. It is also to be noted that the Zonestar LCD is driven at 5V, while the buttons form a voltage divider circuit which is read by an analog pin on the board, which are 3.3V. This means that we need either to step down the supply to 3.3V or supply it with a separate 3.3V line all together. I decided for the latter since the board exposes both lines and we had a spare pin on the connector. This was the quickest solution which also did not need us to but new components.

The board was chosen for its 32bit STM microcontroller and ability to be powered in the 12-24V range, since the original power supply is 19.4V and we still wanted to use it.

Packs a custom extruder, connected to the original board via an ethernet cable. The extruder itself has a little board which holds:

• AD597 thermocouple IC, since it uses a thermocouple and not a thermistor
• Ethernet jack, with connections for heater block and thermocouple output
• Fan power supply supply

The extruder board has six pins which, looked from the top side and the ethernet jack pointing up are:

• Thermocouple IC IN- (also wired to GND, and per the AD597 datasheet (1)
• Thermocouple IC IN+ (2)
• 12V (3)
• Fan control (NOT GND) (4)
• 2 Heather block pins (5,6)

The pins need to be mapped on the ethernet cable, which can be done by:

• Cutting one in half
• The two heather block pins on the board (5,6) each map to to wires in the ethernet cable
• 12V (3) and fan control (4) each map to one wire on the ethernet cable
• IN- (GND) maps to one wire on the ethernet cable. This needs to be wired to a GND pin on the board
• The remaining wire of the ethernet cable is the thermocouple output

After reverse-engineering the board layout, we removed the thermocouple and the IC all together and replaced them with a more standard thermistor, since the IC is not well supported by Marlin and never reported the right temperature. The thermistor is supported by MarlinFW out of the box and required pulling out the thermocouple, desoldering the IC and connecting the thermistor to the pins that originally were for the thermocouple output and GND (pin 1 on board).

Further testing is required for calibrating steps/mm. For Delta systems, this is done by printing a cube and measuring the height. We assume that all towers are equally built, so that every motor uses the same step/mm.

The board fan, the extruder motor fan and the chamber LED strip are powered at 12V. The board we chose does not expose a 12V line, so we used a separate buck converter in parallel to the board straight from the 19.4V suppy.