Frequency Discrepancy Between Two Duet2Ethernet Boards

Awesomer

@Danal That's how I have been controlling the speed % and can tell at which speeds the fan turns on/off.

Danal

Excellent.

Here is an absolutely weird long shot: DWC does cache certain thing about the configuration, and can potentially store them on browser local storage (that is the PC or Mac), and/or it can store certain things in a file on the Duet itself.

Again, a long shot... Try a completely different browser or PC. If you've been using Chrome, use Brave or Edge. Etc. See if there is any difference.

Edit: Oh... and turn OFF the setting to store configuration on the Duet SD card.

Awesomer

Just tried on Edge and Firefox (I use Chrome, usually) and it didn't work. I also have a PanelDue attached and adjusting using that, instead of Duet Web Control, also doesn't make a difference.

Danal

Yeah, it was a shot in the dark.

Well, you have a very intriguing mystery on your hands. I am truly stumped for things even to diagnose this! Maybe sleeping on it...

zapta

Do you have an oscilloscope? Tried to look at the output PWM signals?

(even a cheapo DIY kit should do https://www.aliexpress.com/item/32588011154.html )

Phaedrux

Just to confirm, you've moved the same fan between both printers to eliminate the fan itself, right?

Awesomer

@zapta I have access to one. That seems like a lot of unnecessary work at the moment, though. Maybe if it's the difference between getting a replacement board and being stuck with this one (assuming this second board is faulty), then sure, I'll do a little diagnostics work like this.

Awesomer

@Phaedrux I have tried all three fans I have on all 3 ports -- fan0, fan1, & fan2. One is on the first board, as described above, and it has the same issues on the second board that the other two fans have. The other two fans are new and were purchased at different times -- about a month apart.

Edit: All the fans work fine on the first board.

gtj0

How about swapping the 24v power supplies between boards (or boards between power supplies)?

dc42

Are the fan voltage select jumpers in the same places on both boards?

Are you getting 24V out of the fan ports when they are full PWM? CAUTION: be VERY CAREFUL when measuring it - users frequently short the fan pins together when trying to measure the output voltage, and that blows the mosfet.

jens55

@dc42 said in Frequency Discrepancy Between Two Duet2Ethernet Boards:

CAUTION: be VERY CAREFUL when measuring it - users frequently short the fan pins together when trying to measure the output voltage, and that blows the mosfet.

Oh so true <sigh>