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The Select Mini uses a ESP8266EX WiFi chip for the wireless connectivity.
The ESP8266EX runs the UI and Web Server whereas STM32F103C8T6 chip on the mainboard handles the motion controller
The first few batches of Select Mini's had an issue with the control dial. A UI Controller firmware update in June added some debouncing code to help but it did not completely eliminate the problem.
The newer version of the UI Controller board added a 74HC14 Hex Inverting Schmitt Trigger. This was added to enhance signal condition for control dial. The updated UI Controller boards started shipping sometime in August. The update made a noticeable difference while using the control dial. No more or at least reduced skipping back or jumpiness while cycling through the LCD menu. Complaints are still made even with the newer boards. YMMV
Contact Monoprice support for possible replacement options
Monday - Friday: 6:00AM - 5:00PM PST
email@example.com (try first)
Direct Voltage - MP Select Mini / Malyan M200 3D Printer UI Controller Replacement Board
NOTE: This board have “MALYAN” on the home screen.