How do I figure out if the fans or my octopus was defunct? | VORONDesign | Page 1

still phoenix Dec 12, 2023, 8:26 PM

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I assembled my LDO Voron 2.4r2 rev C kit, triple checked everything as instructed and it was working fine until about 15mins later some of the magic smoke escaped.
The printer seems to be working fine still, but the PCB Fans (Skirt Fans) won't turn on anymore.This was confirmed by configuring the fans as generic fans in Klipper and turning them up with no response. I assume this is because of the burned IC.
Is there any way of determining if defunct fans blew up the IC or if it was simply a bad octopus? Only thing I can think of is plugging the PCB fans into the next socket, risking more smoke.
Resistance of the PCB Cable with the splitterboard and both fans attached is 2.8 Ω.

short willow Dec 13, 2023, 10:46 PM

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If you have access to a lab power supply, you can use that to apply voltage to the suspect fans. If they start turning without massive current draw, they are most likely fine. You definitely want to do this test with a lab power supply because they limit the current and can withstand a short circuit.
The 2.8 Ohms you measured suggest there is a short circuit somewhere, although some DC motors have a very low resistance at standstill, I don't think the fans are using this type of motor.
The Sunon Maglev fans I have laying at my desk measure about 100kOhms

The fans could also be fine and the problem is a short in the wiring.
Try measuring the resistance of each fan disconnected from the splitter board to track down where exactly the short is.

delicate nebula Dec 16, 2023, 11:04 AM

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Did you put the plastic spacer behind the fan splitter board?

still phoenix Dec 16, 2023, 2:09 PM

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delicate nebula Did you put the plastic spacer behind the fan splitter board?

Yes, that one is installed. There is no short with the extrusion on either pin, according to the multimeter.

still phoenix Dec 16, 2023, 2:14 PM

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short willow If you have access to a lab power supply, you can use that to apply voltage to t...

Sadly I don't have access to a lab power supply. I powered them on with the always on pins at the end. They now measure a Resistance of around 15MOhms. I hope whatever has shorted them has now been filed off, but will still try to replace them as soon as I can.
I'll still check any of the other fans that are connected with only one cable and see if maybe they were the problem.

short willow Dec 16, 2023, 3:13 PM

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If they are working fine now I suspect the wiring. The fans themselves are probably ok

#How do I figure out if the fans or my octopus was defunct?