DreamMaker 3D 3.3.6

The stylish and smart 3D printer evolved to be the most reliable and user friendly choice!

By mpl
#24830
Nunika wrote:
daniel dom wrote:Same Here,
Let me try to explain how current adjustment is made. Original driver has a fixed resistance divider 20k/3.3k and 0.1R sensing resistor. Driver current is in this case calculated with formula from datasheet 3.3V * 3.3kR / (20kR+3.3kR) * 5 * 0.1R = 0.93A.

On replacement driver, there is 10k trimmer and everybody here is talking about resistance between ground and middle pin of trimmer. Replacement drivers also use 0.1R sensing resistors, so if you adjust it to 600R, current is 3.3V * 0.6kR / 10k * 5 *0.1R = 0.4A.

To get same amount of power on replacement driver, you need to adjust it to 1.4kR. Don't adjust it to higher value because this can burn driver or overheat stepper motor or overload power supply.

Base on those calculations, you actually don't need to replace whole driver, only change 3k3 resistor (marking 332) on original driver to 1k5 (marking 152) only on tower stepper drivers. Didn't try it but it should work.

P.S. I also have v1.1 board.


Thanks for the great explanation of what actually happens! I've tried replacing 3k3 resistors with 1k5 on the original drivers and I've been running it for couple weeks. Noise level did go down noticeably, but I also started getting missed steps in the prints. Very very rare, but even one is enough to ruin the print. Maybe 0.4A is a bit too low for these motors (anyone know what they are rated for?) Replacing it with 2k resistor should give 0.6A current, right?

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