When i put my PSU on the other day there was a rattling sounds that i recognize as something hitting a fan. No big deal i thought, i disassembled the thing all the way to the second fan, and sure enough a small bit of plastic fell out of the enclosure. Probably some debris.
Here’s where i fucked up - when reassembling the units i mixed up the fan molex connectors and connected the internal 12v fan to the external 24v slot. A little spark and some smoke later i realized what i had done.
Still i thought, no big deal I’ll just replace the fan. Only i could not get the NMB 2404kl-04w-b30 12v 0.13A fan anywhere, not unless i bought a box of 200 for 800 EU. The closest i could get in size was the Sunon mf60101v1-1000c.a99 12v 1.43W fan. Doing some calculations on the current/power the NMB is 1.56W and the Sunon is 0.12A , so without knowing better i thought, good enough?
To install this fan i had to change the polarity of the molex connector, which i’ve done before so i figured, no big deal. I plugged everything in and it seems to work, only the fan works in bursts. It comes on for a second or so, then stops for maybe 3 seconds, and comes on again. I didn’t leave it on in it’s disassembled state for longer than 3 cycles.
Now i have absolutely no idea if something else is broken, or if there’s something different between these fans i don’t understand, or if it’s supposed to work like this. Any help?
From what I understand, the internal fan may behave differently depending on whether you have the original Kickstarter power supply or the updated one. This might be correct behaviour for the fan in the updated power supply. I have the original and so can’t check, but support should know if no one else replies here.
Fan rating sounds fine for sure. Stupid comment here possibly but have you just wiggled / pressed on the contacts good, make sure you don’t just have a weak connection after flipping the polarity of the 2 pins in the molex?
Do you have a multimeter to maybe check the voltage at the pins from the PSU while it’s on with no fan and disassembled - see if the voltage you’re getting is constant or intermittent? I’d have guessed if they wanted to speed control this they’d PWM the voltage not cycle on-off.
Maybe you just got unlucky with a bad fan. Have any other 12V source to test it directly with?
This is a great reply, it gives me a lot of “debug” ideas to try. I probably have a multi meter and a 12V power source somewhere, a Raspberry pi, Arduino and PC motherboard come to mind.
Yeah, dangle one of the 4-pin Molex cables out of your computer case from a PSU and you have easy access to both 5 and 12V stable sources. Alternatively eyeball your different wall warts for various items like external hard drives, Alexa or Google speakers, clock radios, etc. At least one of them is probably 12V and its pretty easy to rig up a couple leads to the coaxial connection endpoints (don’t go sticking things in a little USB connectors if you don’t want to ruin it for real devices though…)
EDIT - just checked an Amazon Echo speaker, and that wart was 15V, unfortunately…But I have a small LED desk lamp that’s a 12V transformer.
In my case I have a gaming throne / desk chair replacement built up from 8020 aluminum extrusion framing with a car seat on it, so I got a 12VDC30A (“LED Driver” type) SuperNight PSU that sits under it to power the adjustment motors, ventilation fans, etc, and I keep a spare cable off of it for a 12V test source.
Old computer PSUs are great tools. I picked up a break out board that takes a ATX 24 pin PSU connector, and outputs -12V, +12V, +5V, and +3.3V. That one isn’t available anymore, but there are plenty of other offerings in the rain forest.
I’ve also replaced a couple of fans, and I’ve had to reverse the polarity. I’m using these 24V fans on my original (after reversing the polarity). It’s a 5 pack. If I destroy something once, it’s probably going to happen a second time…
I have those exact same fans for the external PSU cooling, but sadly the internal one is 12v. And that’s where my lack of knowledge of electronics stops me
There has been some discussion on whether the internal fan is even necessary.
I believe a few people on FB disabled their’s for sound reasons without problems.
One thing other’s have also done is remove some of the plastic ‘baffles’ in the front that is used to diffuse the light of the power supply. They found it serves no real purpose and is just cosmetic. Removing it improved flow and also made it quieter.
You might want to just do that mod and give it a go without a fan. Worst case scenario it dies prematurely, but that might still be quite some time from now.
Hello again! I have some follow up information thanks to the tips you gave me
I had a 12v 1a DC adapter in my box of forgotten adapters. Taking out the fan cables of the molex connection and touching the adapter plug (red inside and black outside as indicated by the adapter info) made the fan spin nicely. So it doesn’t seem broken.
I also had a multimeter. I plugged the PSU into the wall socket but not into the snapmaker, and had everything but the internal fan connected. I measured the voltage in the fans connector - 24v! Very stable, but isn’t it supposed to be 12? If I connect the fan it seems to go way faster than when it’s connected to the 12 DC adapter.
Summary: fan works well with 12v different power source, but the female molex on the PSU outputs 24v now, unless I’m using the multimeter wrong.
Thanks for that info. I had already removed the cosmetic plastic and replaced the outer fan with the WINSIN one for sound reasons. I suspect the fans might be nececary when using the more powerful lasers, but perhaps not for 3d print? Depending on what support say, my next step might be to replace the PSU, so i Might as well run it without a fan first. As long as there’s no risk to the snapmaker itself?
For anyone following this, i have found the source of the problem, nothing was broken. There are 3 molex connectors inside the PSU. First i connected the fan to the external fan connector, which burnt the fan. Then once i got a replacement, i mistakenly connected it to the decoration LED light molex connection, which also is 24V. Thankfully it didn’t burn out, and measuring the voltage with a multi meter as @rtrski suggested guided me to realize it’s not the correct connection. I looked at the PSU and found the 3rd molex, connected the fan and now my PSU is working just right.
I knew i should have documented the thing as i was disassembling it, i know myself well enough to be certain i’d forget / mix something up if i didn’t. I was right XD
