RE: How does a 3 wire nozzle coolng fan work on the MK3S+
"you're sharing the most useless information" = trying to be helpful? Wow. I guess the community will decide. It seems you haven't tried to troubleshoot a fan that's not working right before, so you find my info useless. Funny how others have used the info to share some useful suggestions already.
You're the only one being rude and insulting people here. Perhaps watch this and don't be so sensitive...
RE: How does a 3 wire nozzle coolng fan work on the MK3S+
"you're sharing the most useless information" = trying to be helpful? Wow. I guess the community will decide. It seems you haven't tried to troubleshoot a fan that's not working right before, so you find my info useless. Funny how others have used the info to share some useful suggestions already.
You're the only one being rude and insulting people here. Perhaps watch this and don't be so sensitive...
I didn't start this thread to start an argument. I'd like to suggest that we hit the reset button and be the first to say we got off on the wrong foot. I will take you at your word that you had intended to help, regardless of how your intention was worded. Let's just move on, shall we?
RE: How does a 3 wire nozzle coolng fan work on the MK3S+
Thanks for your help!
I was able to collect more info tonight. At 240 fan setting, the fan runs fine, but I can't really hear the difference between rpm @240 and @255 (max). starting @235 and below, the fan turns on for half a second or so, spinning a few revs, then shuts off a few seconds (4-5) and repeats. Then after a couple of cycles, I get an error message: "cooling fan error", but it still continues on this on/off cycle, then beeps with the error message again, then the whole cycle repeats. So it appears that the yellow wire is sending some signal to the controller, right?
If so, could it be that due to the construction of the windings of my 5020 fans (from different suppliers), it takes more current to get it started, but by the time it starts, due to the lag in response, the signal is at zero again, because of PWM cycling, so it never really gets started properly...
If this is true, then why would a vendor sell a 3 wire 5020 fan? (rhetorical)
Or did I really buy defective fans from different suppliers? Seems very unlikely.
An interesting problem. I do suspect it is current related but I find it hard that that small difference would have an effect. The frequency of the PWM is in the 20-30 KHz range which is over 120,000 pulses per minute. The fan should have a current rating on the label. Larger fans do have a higher current rating as there is more material to turn. The schematics for the Einsy board is online and there doesn't look like there is any real current limiting method on the board. What does concern me and may be causing your issue is that the board is switching the ground, not the power. I will have to look at this closer. I would confirm the wiring for your fan is the same.
Interesting concern, switching the ground instead of the power. I don't even know where to start investigating that. Are you asking if I can switch the connections of my fan to connect black to red instead of black to black? I'm not sure if this will harm the fan or not.
RE: How does a 3 wire nozzle coolng fan work on the MK3S+
In my searches, I can across this article that covers this discussion. It explains the issues with switching the GND and how it affects the tach reading.
Good article. I've actually read this before, but didn't quite understand some of the points. Reading it again, the 3-wire fan should be using linear control of speed, and my main take away is that the 5020 fan mfr's that sent me fans may not be using the right fan controller IC where the tach signal remains on while the voltage cycles on-off via PWM signals - so perhaps the controller they are using is not doing that? Without the right fan controller IC, the tach signal gets chopped off, and this chopped signal "confuses" the PWM signal that the printer sends to the fans?
RE: How does a 3 wire nozzle coolng fan work on the MK3S+
Interesting concern, switching the ground instead of the power. I don't even know where to start investigating that. Are you asking if I can switch the connections of my fan to connect black to red instead of black to black? I'm not sure if this will harm the fan or not.
No, I am not. Just to ensure that the three wires are the correct wiring and that the fan is turning in the correct direction. There should be an arrow on the fan showing air flow and rotation. If I had the fan, I would connect to the scope and monitor it. From the article, it states that the tach when switching the ground does get screwed up. This is why I am sort of surprised. It may also be that the PWM voltage is affecting the sensor for RPM. I have a broken fan, I should look closer at the circuit to see if there is any filtering for the power.
There are so many variables at play here and without the right tools, it is hard to know what is going wrong. There may be an issue with the fan itself or cheap components.
RE: How does a 3 wire nozzle coolng fan work on the MK3S+
No, I am not. Just to ensure that the three wires are the correct wiring and that the fan is turning in the correct direction. There should be an arrow on the fan showing air flow and rotation. If I had the fan, I would connect to the scope and monitor it. From the article, it states that the tach when switching the ground does get screwed up. This is why I am sort of surprised. It may also be that the PWM voltage is affecting the sensor for RPM. I have a broken fan, I should look closer at the circuit to see if there is any filtering for the power.
There are so many variables at play here and without the right tools, it is hard to know what is going wrong. There may be an issue with the fan itself or cheap components.
I confirmed the fan is blowing quite well when running at full speed. Unfortunately I don't have a scope (or know how to use one), so I don't have the knowledge or skills to proceed further.
RE: How does a 3 wire nozzle coolng fan work on the MK3S+
On the fan should be arrows showing the direction of air flow and blade rotation. Ensure that it is blowing in the correct direction. I suspect that the fans you are trying to use may have an issue with PWM control. It could be tested with a Pi or Arduino to see how if the fan works as expected. Removes the printer from the loop.