Berd-Air - poor pwm response with ez switch

ockray83 · 7 Apr 2021, 23:47

I recently bought a berd air kit from makerhive to install on my delta printer with a duet 2 wifi. I bought the extra "ez switch" they sell as well, to isolate & protect the duet from the pump. I have everything wired and plumbed and at 100% I'm blown away (no pun intended) at the amount of air this thing pushes through that little cooling ring.

The problem is, I can't seem to control the speeds in between 0 and 100% very well.
Initially I had an awful noise from the pump at anything below about 80%.
After researching this on the forum a bit, I saw people had to change their frequency to the 25k range to get better performance and reduced noise, so I tried that. Now the awful noise is gone, but I don't seem to get a change in the pumps output unless I make a drastic change (more than 50% shift). I've also tried various other frequencies with varying thresholds of poor response and awful noise.

I saw a bunch of berd air posts while researching this, but none that involved the e-z switch I'm using. I'm wondering if the switch is expecting a fan input with switching occurring on the positive lead, while I believe the duet switches the negative pin. Would m106 i1 switch pwm to the positive pin?

For reference, this is an example of the switch, makerhives web page seems broken right now
https://www.kis3d.de/en/products/mosfet-modul-berd-air-e-z-switch-pwm-controller

Phaedrux · 8 Apr 2021, 01:50

@ockray83 said in Berd-Air - poor pwm response with ez switch:

Would m106 i1 switch pwm to the positive pin?

No. Inverting just means that switching has changed from high to low, or vice versa.

That said, I'm not really sure what the little mosfet module "EZ switch" does in this case.

ockray83 · 8 Apr 2021, 11:44

It's meant to protect the control board by isolating the fan pwm cconnection from the pump circuit. The ez switch has connections from the psu to the pump on one side and on the other side it takes in a 2 pin 12-24v fan signal from the controller

o_lampe · 8 Apr 2021, 13:04

@ockray83
Just to be sure, did you check the jumper for the PWM fans is at the 'Vin' position?
Even if we'd know which type of MOSFet it is, we don't know if the optocoupler inverts the signal.

I believe it's common to switch a MOSFet to GND. Switching to Vin requires a bootstrap circuit but I don't see any.

ockray83 · 8 Apr 2021, 14:13

@o_lampe The jumper is in the Vin position.
The MOSFet is identified as F5305S
The coupler appears to be an EL817
I'm not certain if that helps at all.

It looks like makerhive sells all their berd air kits with these switch boards now. If this were a common issue I think I would find it in forum posts somewhere. Maybe I have a defective board/pump?

Side note, I did try running a print at 100% speed, just to see what happened and I noticed that while the heated bed output light was illuminated, I got a slight change in pitch from the pump and checking with a meter, the power going to the pump was dropping off by .08vdc and rising back again once the light was out. At the moment the two are sharing the same PSU.

Update: makerhive got back to me and are sending me a new switch, they believe mine is defective. I should get it in a few days.

uk25 · 3 Jun 2021, 21:10

@ockray83 said in Berd-Air - poor pwm response with ez switch:

Update: makerhive got back to me and are sending me a new switch, they believe mine is defective. I should get it in a few days.

Just got the same problem... Did you already receive a new ezswitch from makerhive and did it really solve your issue?

ockray83 · 12 Nov 2021, 18:02

@uk25

Its been a while since I've been able to mess with my printers, sorry for the delay. I got the new switch from MakerHive installed and my control has not really improved. I get a small 'controllable window' within the S0-S255 range which I can shift with frequency changes, but nothing I've done has widened the span of that window. Anything below the controllable range results in the offensive buzzing sound with little to no output of air from the pump. Anything above the controllable range results in no change in output (S200-S255 may output the same amount of air, for example). I also installed a diode across the terminals as recommended in other forum posts, with no change in performance. If you figured your issue out, please let me know as I am out of ideas to make this work.

Dougal1957 · 11 Dec 2021, 18:12

@ockray83 have you tried adjusting the PWM Frequency in RRF I use a bird air system (have done for years) but I used a power expander from Reprap.me on mine and don't have any issues. Check M950 Qnn parameter

uk25 · 12 Nov 2021, 18:37

@dougal1957 said in Berd-Air - poor pwm response with ez switch:

@ockray83 have you tried adjusting the PWM Frequency in RRF I use a bird air system (have done for years) but I used a @dougal1957 on mine and don't have any issues. Check M950 Qnn parameter

Thanks, @dougal1957 for another lead. Looks like the power expander hasn't optoisolator as utilized in e-z switch controller. So maybe that's the main reason for such poor pwm control.

Fred-Y · 12 Nov 2021, 21:41

I have the set from Makerhive with the EZ switch on one of my printers, below is what I use in the config.g

M950 F0 C"fan0" Q100                                ; create fan 0 on pin fan0 and set its frequency
M106 P0 S0 H-1 C"Part Fan"                                      ; set fan 0 value. Thermostatic control is turned off

The pump is fairly quiet and I can adjust the speed.

I bought that kit 2 or 3 years ago so they might have made some changes.

ockray83 · 12 Nov 2021, 21:55

@fred-y
It looks like the m950 command isn't supported by my board's current firmware (2.05.1). I haven't updated this thing in a long time. I'll have to go through the update and see how it does with the commands you've provided.

uk25 · 13 Nov 2021, 00:07

@ockray83 You can just use F100 parament in M106 on the earlier firmware version to set the frequency. Currently, I'm not near my printers and can't try that.

Also, have to mention that previously, everybody suggested using F about 25500, but now Makerhive advises to set it extremely low. Hope that helps.

Phaedrux · 16 Nov 2021, 04:41

@ockray83 said in Berd-Air - poor pwm response with ez switch:

@fred-y
It looks like the m950 command isn't supported by my board's current firmware (2.05.1). I haven't updated this thing in a long time. I'll have to go through the update and see how it does with the commands you've provided.

If you still have access to DWC. Upload these 3 zip files, one at a time in the system tab. Don't extract them first. Reboot after each. Use M115 in the gcode console to verify the firmware has been applied.
https://github.com/Duet3D/RepRapFirmware/releases/download/2.05.1/Duet2Firmware-2.05.1.zip
https://github.com/Duet3D/RepRapFirmware/releases/download/3.0/Duet2and3Firmware-3.0.zip
https://github.com/Duet3D/RepRapFirmware/releases/download/3.3/Duet2and3Firmware-3.3.zip
That will get your firmware and DWC up to date.

You can see the change logs here:
https://github.com/Duet3D/RepRapFirmware/wiki/Changelog-RRF-3.x

For your config, might be a good idea to run through the configurator tool and generate a fresh set for RRF3.
https://configtool.reprapfirmware.org/Start

Backup your existing config files in the sys folder in case you want to switch back to RRF2. It’s easy to switch back and forth, just upload the zip file for the version you want and then upload your config files.

These documents will come in handy during the conversion.
https://duet3d.dozuki.com/Wiki/RepRapFirmware_3_overview
https://duet3d.dozuki.com/Wiki/Gcode