Soldering resistor onto A4988's ROSC pin
Posted by Ohmarinus
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Re: Soldering resistor onto A4988's ROSC pin February 04, 2015 02:11PM |
Wooo! Found it 
You short the R4 resistor on A4988 stepper drivers... The fix is described >>HERE<< (but in GERMAN)
-David
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You short the R4 resistor on A4988 stepper drivers... The fix is described >>HERE<< (but in GERMAN)
-David
Find me online at:
Thingiverse
Instructables.com
Check out my FolgerTech Prusa i3 (plexi) at MindRealm.net
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Re: Soldering resistor onto A4988's ROSC pin February 04, 2015 02:41PM |
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MindRealm
Wooo! Found it
You short the R4 resistor on A4988 stepper drivers... The fix is described >>HERE<< (but in GERMAN)
Simply shorting it? But, R4 to what pin? Ground? I don't have to put a resistor from R4 to ground, but simply short R4 to ground? This sounds easier than I thought!
From translating it I found:
"so I have the R4 10k resistor bridges"
So this probably means I have to pull R4 to ground with a 10K resistor?
There is another German topic about this:
[translate.googleusercontent.com]
Edited 2 time(s). Last edit at 02/04/2015 02:47PM by Ohmarinus.
http://www.marinusdebeer.nl/
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Re: Soldering resistor onto A4988's ROSC pin February 04, 2015 04:13PM |
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dc42
Download the A4988 datasheet and work it out from that. I'd do that for you, but it's not very practical on a mobile.
I'm not easily insulted, so I'm not, but really, I did that already and I'm not so good at that. Hence me asking help from the community
The file is here:
[www.pololu.com]
PDF:
[www.pololu.com]
http://www.marinusdebeer.nl/
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Re: Soldering resistor onto A4988's ROSC pin February 04, 2015 06:22PM |
Thanks, it's interesting that they tell what they did, but don't show a picture of the physical change they made to the stepper driver..
Judging from this somewhat unclear image, it looks like you only have to bridge the resistor:
Title of the image is:
Edited 1 time(s). Last edit at 02/04/2015 06:37PM by Ohmarinus.
http://www.marinusdebeer.nl/
Judging from this somewhat unclear image, it looks like you only have to bridge the resistor:
Title of the image is:
Quote
On the Pololu A4988 boards a small resistance has to be bridged, here done with a small piece of wire:
[Attachment 37445 hack_pololu.jpg]
(Picture by hardware Killer)
Edited 1 time(s). Last edit at 02/04/2015 06:37PM by Ohmarinus.
http://www.marinusdebeer.nl/
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Re: Soldering resistor onto A4988's ROSC pin February 05, 2015 01:44PM |
First experiments sound very promising, will upload a side-by-side comparison video later today Vibration is down by a lot and noise production by a bit
Oh, and it's superhard to solder an SMD that isn't stuck to the PCB! So I simply removed them and pulled a solder trace to short out R4.
Edited 1 time(s). Last edit at 02/05/2015 01:54PM by Ohmarinus.
http://www.marinusdebeer.nl/
Vibration is down by a lot and noise production by a bit Oh, and it's superhard to solder an SMD that isn't stuck to the PCB! So I simply removed them and pulled a solder trace to short out R4.
Edited 1 time(s). Last edit at 02/05/2015 01:54PM by Ohmarinus.
http://www.marinusdebeer.nl/
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Re: Soldering resistor onto A4988's ROSC pin February 05, 2015 04:00PM |
I was actually really skeptical of this modification. Why would grounding a pin reduce vibration, and if its so helpful why not make it default behavior?
It turns out that this mod is for real, and confirmed in the datasheet.
Note that in a 3d printer the stepper motor is almost exclusively low speed, especially in pulley systems that have low mechanical reduction.
The default behavior switches decay modes and is more efficient, but has discontinuities at the transition. At low speeds this is reflected by a "jump" which is likely what causes your vibration.
It turns out that this mod is for real, and confirmed in the datasheet.
Note that in a 3d printer the stepper motor is almost exclusively low speed, especially in pulley systems that have low mechanical reduction.
The default behavior switches decay modes and is more efficient, but has discontinuities at the transition. At low speeds this is reflected by a "jump" which is likely what causes your vibration.
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Re: Soldering resistor onto A4988's ROSC pin February 05, 2015 06:01PM |
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Ohmarinus
First experiments sound very promising, will upload a side-by-side comparison video later today
Oh, and it's superhard to solder an SMD that isn't stuck to the PCB! So I simply removed them and pulled a solder trace to short out R4.
Maybe this mod makes it possible to screw down the current a bit, because it says there is less chance in skipping steps. That would decrease the sound level even more.
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Re: Soldering resistor onto A4988's ROSC pin April 22, 2019 09:32AM |
I was looking for an old thread I swore I had read somewhere in the past about shorting a pin on the A4988. I had not expected it was my own thread from more than four years ago.
Anyway, wanted to let you know that even after all this time, the CoreXY-lasercutter still runs perfectly silent. It's such a nice mod, that I've also done this mod to my other 3D-printers
Recently, my 3D-printer that I currently had working, has died with electrical issues and I have replaced the stepper drivers for cheap old A4988's, these ones I still have to short so I can record a before and after if anyone is interested? I know that the reprap printers are at the brink of disappearance, the forums have gone very quiet and everyone around me simply buys Chinese ready-made printers. No need for DIY anymore it seems. Even though I think DIY is still the best way to learn anything about these machines so I'll just wholeheartedly keep doing this.
http://www.marinusdebeer.nl/
Anyway, wanted to let you know that even after all this time, the CoreXY-lasercutter still runs perfectly silent. It's such a nice mod, that I've also done this mod to my other 3D-printers
Recently, my 3D-printer that I currently had working, has died with electrical issues and I have replaced the stepper drivers for cheap old A4988's, these ones I still have to short so I can record a before and after if anyone is interested? I know that the reprap printers are at the brink of disappearance, the forums have gone very quiet and everyone around me simply buys Chinese ready-made printers. No need for DIY anymore it seems. Even though I think DIY is still the best way to learn anything about these machines so I'll just wholeheartedly keep doing this.
http://www.marinusdebeer.nl/
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Re: Soldering resistor onto A4988's ROSC pin April 24, 2019 04:31AM |
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obelisk79
I'd love to see(hear) the before and after
Okay, so I have made a video with before and after. Sadly somehow my video editing software cannot use the video files from my phone (Pocophone F1) so I have uploaded two videos with before and afters.
Before (part 1):
[youtu.be]
After (part 2):
[youtu.be]
In video #2 I show the specific mod at the end.
I hope it's clear
any comments are welcome as I'd like to hear your reactions.Edited 1 time(s). Last edit at 04/24/2019 04:47AM by Ohmarinus.
http://www.marinusdebeer.nl/
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Re: Soldering resistor onto A4988's ROSC pin April 24, 2019 04:48AM |
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Dust
@Ohmarinus
ffmpeg can convert nearly all video and audio formats, and it free
Seems only slightly quieter... and that could be due to different recording devices...
It's recorded on the same phone
I think it's a big difference. Maybe it's the playback device you're using? j/k.http://www.marinusdebeer.nl/
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