Completely dead BaoDiKai 120MM fan

[Pentium4]

So this was running in a computer for a while, working fine. I went to do my every-other-day check to make sure fans are spinning, no clicking hard drives, etc. of all my computers running. I noticed that there was no fan exhaust on this machine. I shined a flashlight to see that the fan was not spinning. I thought that maybe it seized but thought that was strange because I always oil fans after I recap power supplies.

I thought that maybe it was the PSU but I pulled it and plugged it straight into the molex of another PSU. I tried 5V and 12V, nothing. No tick, it doesn't even try. Plugged into 12V and tried 'kick starting' it by manually spinning it but it has no life.

I got close to the bearing to see if I could smell anything burnt but it doesn't smell at all and spinning it with your finger, it spins very well. The sleeve bearing seems perfectly healthy. It was made in November 2011 but does not have a lot of use on it.

Has anyone had a cheap fan like this just die for no reason? It's a modded power supply but it seems odd that any refurbishing mods would cause a fan to die. It's just scary to think that a fan could die for no reason! Luckily the PSU was only powering an 80W load so even with no fan, it wasn't that warm.

[stj]

anything can fail
it may be a bad chip,
or a broken coil.
or more likely based on fixing transformers, it may have broken a winding at the binding post where it is stressed during manufacture.

[Topcat]

I have a similar but weird one with a cisco switch, it has 4x 40mm fans in it. It throws a fan error code; not because the fan has stopped or is running slow....but rather one is running TOO FAST! Whodda thunk that....the closer I looked, sure enough, its visibly noticeable that one is running significantly faster than the others. They're high RPM fans to begin with, its a loud/annoying critter....but yet one is still running too fast. I swapped the fast one with one of the others to determine if it's the mainboard/port or the fan itself. The 'fast fan' still ran fast on another port....and of course the error was still there, just on another port. Replaced the fan, no more codes. I'm guessing maybe a winding internally shorted? Not really sure why it did this.

[Uranium-235]

Cheap fans die all the time. If you've been oiling it than you've been extending it's life beyond what cheap fans usually run for

[Pentium4]

Originally Posted by stj

anything can fail
it may be a bad chip,
or a broken coil.
or more likely based on fixing transformers, it may have broken a winding at the binding post where it is stressed during manufacture.

I will see if I can take it apart without breaking it lol. If the winding is broken, will it be easy to spot?

Originally Posted by Topcat

I have a similar but weird one with a cisco switch, it has 4x 40mm fans in it. It throws a fan error code; not because the fan has stopped or is running slow....but rather one is running TOO FAST! Whodda thunk that....the closer I looked, sure enough, its visibly noticeable that one is running significantly faster than the others. They're high RPM fans to begin with, its a loud/annoying critter....but yet one is still running too fast. I swapped the fast one with one of the others to determine if it's the mainboard/port or the fan itself. The 'fast fan' still ran fast on another port....and of course the error was still there, just on another port. Replaced the fan, no more codes. I'm guessing maybe a winding internally shorted? Not really sure why it did this.

That is a very odd issue to have. The sound of those things drive me nuts. Can't believe that they last as long as they do with how high RPM they run.

Originally Posted by Uranium-235

Cheap fans die all the time. If you've been oiling it than you've been extending it's life beyond what cheap fans usually run for

Not in my experience! This is only the second time I've seen this. I've even seen cheap fans seize up and run for years, have their PCB turn dark and still works after cleaning and oiling it.

[petehall347]

its done its job .. send it in for melting down into a new one .

[Topcat]

Originally Posted by Pentium4

Not in my experience! This is only the second time I've seen this. I've even seen cheap fans seize up and run for years, have their PCB turn dark and still works after cleaning and oiling it.

That's been my experience as well. I've disassembled & repacked grease in many cheap fans that are still in quiet operation; some a good 10+years ago. I think I've seen only a small handfull of fans that failed due to electrical problems.

[ChaosLegionnaire]

yea i killed a nice b-gears b-blaster ball bearing fan before. i was trying to blow out the dust off the fans and butter fingers slipped and the straw i was using to stop the fan blades from spinning when i blew it with the datavac fell off. the fan blades spun like mad. didnt try to stop it as i was afraid it might amputate my finger. not sure how many excessive rpms the strong static pressure wind from the datavac put on the fan.

connected it back. fan didnt spin. according to momaka, the excessive back emf from spinning excessively must've fried the fan controller chip. coils were ok and not fried. ball bearings are fine and still good. i can still reuse the ball bearings on other b-gears fans of similar size in case they get busted ball bearings. so im poorer by US$15 and lost one of my ball bearing fans. those b-gears fans arent cheap! they are USA quality!

[eccerr0r]

I have this 40mm fan that spins fine by finger but won't power up, so I guess same or similar issue, the BLDC controller chip lost its magic smoke or a winding/solder joint broke.

[Topcat]

Originally Posted by ChaosLegionnaire

yea i killed a nice b-gears b-blaster ball bearing fan before. i was trying to blow out the dust off the fans and butter fingers slipped and the straw i was using to stop the fan blades from spinning when i blew it with the datavac fell off. the fan blades spun like mad. didnt try to stop it as i was afraid it might amputate my finger. not sure how many excessive rpms the strong static pressure wind from the datavac put on the fan.

connected it back. fan didnt spin. according to momaka, the excessive back emf from spinning excessively must've fried the fan controller chip. coils were ok and not fried. ball bearings are fine and still good. i can still reuse the ball bearings on other b-gears fans of similar size in case they get busted ball bearings. so im poorer by US$15 and lost one of my ball bearing fans. those b-gears fans arent cheap! they are USA quality!

He's right. Always stick your finger in the fan as a stop before spraying with compressed air (I use the air compressor in the garage).....after might have a bloody result...or atleast make you say swear words!

[Pentium4]

I found the issue I believe. I managed to get the shaft off without breaking the tiny clip. I analyzed it and saw a loose piece of wire but then I went to look at the transistor. I barely touched it with a small pin and it moved significantly. I think some/all of the joints are broken or the solder was weak and broke. The trouble is... I can't get the board off! It feels like it's mended into the plastic somehow lol. Does anyone have an idea of how to get the board off without breaking it?

[Pentium4]

Originally Posted by petehall347

its done its job .. send it in for melting down into a new one .

I'm not letting it get off that easy I would be surprised if it even saw 10,000 hours of use!

Originally Posted by Topcat

That's been my experience as well. I've disassembled & repacked grease in many cheap fans that are still in quiet operation; some a good 10+years ago. I think I've seen only a small handfull of fans that failed due to electrical problems.

Usually it's this easy. Just curious, what oil/grease do you use? I have been using Tri-Flow and it's been great as long as the seal it properly sealed.

Originally Posted by eccerr0r

I have this 40mm fan that spins fine by finger but won't power up, so I guess same or similar issue, the BLDC controller chip lost its magic smoke or a winding/solder joint broke.

You should check it

[stj]

to remove the board you usually drive out the bearing,
it is forced in causing the plastic to expand and jam the motor in.

[Topcat]

Originally Posted by Pentium4

Usually it's this easy. Just curious, what oil/grease do you use? I have been using Tri-Flow and it's been great as long as the seal it properly sealed.

I clean them out thoroughly and use a spray grease called ZEP2000. I've never had to redo one, it never dries out.

Here's a little more info; 3rd paragraph: https://www.badcaps.net/forum/showpo...8&postcount=13

[Pentium4]

Originally Posted by stj

to remove the board you usually drive out the bearing,
it is forced in causing the plastic to expand and jam the motor in.

I'm not sure what you mean by 'drive out the bearing' ?

Originally Posted by Topcat

I clean them out thoroughly and use a spray grease called ZEP2000. I've never had to redo one, it never dries out.

Here's a little more info; 3rd paragraph: https://www.badcaps.net/forum/showpo...8&postcount=13

Excellent, thanks! I will see if I can find that. If it doesn't dry out, it's automatically a better solution

[Topcat]

Originally Posted by Pentium4

Excellent, thanks! I will see if I can find that. If it doesn't dry out, it's automatically a better solution

You can find it on ebay or amazon, no problem....but I'll prepare you for the sticker shock, its not cheap....but it's useful for a lot of things besides fans....and a little goes a long way!

[ChaosLegionnaire]

Originally Posted by eccerr0r

I have this 40mm fan that spins fine by finger but won't power up, so I guess same or similar issue, the BLDC controller chip lost its magic smoke or a winding/solder joint broke.

yea momaka also mentioned something about symptoms like those. if it wont spin up on its own but only with a finger or push, it means one or more of the fan phases or coils is busted. for me, i couldnt reach the blades because the fan grill was in the way. i gave it a blow with air from my lungs instead and it spun up. lol u can also stick a wooden stick or plastic straw in the fan grill to "help" the partly broken fan spin up.

[stj]

Originally Posted by Pentium4

I'm not sure what you mean by 'drive out the bearing' ?

the bronze bushing in the center of the motor is rammed in from one end - you need to use something to drive it out again

[goodpsusearch]

I use this to oil the fans:

https://www.provataki.gr/images/stor...hine%20Oil.jpg

singer sewing machine oil

[momaka]

Originally Posted by Pentium4

I will see if I can take it apart without breaking it lol. If the winding is broken, will it be easy to spot?

Probably not.
But if you can get access to the PCB (should be able to - I'll elaborate), you can check resistance on the windings right at the PCB. Cheap fans like this usually only have two windings... though it will be extremely difficult to tell how their are wound (I still actually haven't figured that out on some of the fans.) However, the IC that most cheap fans use tends to be just a simple 4-pin type, having only Vcc, Ground, L1, and L2. L1 and L2 are the outputs of the IC that drive the two windings. Checking resistance between L1 and ground as well as L2 and ground should reveal if something is broken.

Originally Posted by Pentium4

Not in my experience! This is only the second time I've seen this. I've even seen cheap fans seize up and run for years, have their PCB turn dark and still works after cleaning and oiling it.

Same here.
Actually, I revived a fan with a burned PCB and windings 6 months ago, just as a challenge to see if it can be done. Despite the original driver/IC in the fan looking completely burned, it worked absolutely fine.
Also, cheap sleeve bearing fans can run 10x longer with proper lubrication and cleaning. So there's no need to junk them if you see one seized... unless it has burned windings or something that major, of course.

Originally Posted by Pentium4

The trouble is... I can't get the board off! It feels like it's mended into the plastic somehow lol. Does anyone have an idea of how to get the board off without breaking it?

Yes.

First, remove the fan wires from the grooves in the housing. You want them "floating around" and only attached to the PCB.
Next, with a thin cloth (not required but recommended), grip the stator (the metal piece in the center on which the windings are attached to) and rotate back and forth with your hand around the direction of the fan axle/bearing. Depending on how well they (the factory) glued the stator to the center post (typically plastic on cheap fans), you should be able to make the stator turn a little more every time. If not, try heating the stator and housing with a heat gun (or hot air) to maybe 50-60C (so that you can still hold it right after without getting burned) and try again. If not, heat a little higher to maybe 70-80C and definitely use a cloth this time to hold the stator while trying to turn it.
Eventually, the glue holding the stator down to the center plastic post (which also has the sleeve bearing inside) will give. Once you can get it to turn a few mm, start pulling upwards on the stator while still rotating it back and forth. The PCB is attached to the stator on 3 or 4 metal posts, so it should rotate and come out with it.

To check for open windings:
Once you have the stator + PCB assembly, locate the driver IC. Most cheap fans usually use a 4-pin IC, like FS276 or similar (i.e. 2-phase motor driver.) In the case of such, just check resistance to between ground and output 1 (winding #1) as well as ground and output 2 (winding #2.) The other two pins on the IC should be Vcc and ground. So overall, it should be fairly easy to trace out the PCB. If both windings show similar resistance to ground (probably 100 Ohms or less), they should be good.

Originally Posted by stj

the bronze bushing in the center of the motor is rammed in from one end - you need to use something to drive it out again

True. But you don't need to remove the brass bushing (sleeve bearing) to take the fan apart.

Originally Posted by eccerr0r

I have this 40mm fan that spins fine by finger but won't power up, so I guess same or similar issue, the BLDC controller chip lost its magic smoke or a winding/solder joint broke.

Might be an open winding. Does it never spin up from a full stop or does it only seem to do that when it has stopped at a certain position. If it's the latter, it's probably a bad winding or driving circuitry to the winding. Easiest way to check without taking the fan apart to determine this is to take a permanent marker and just draw a single line on one of the blades and the position where it has stopped. Then power on the fan and see if it spins up. If yes, it means it has stopped on the "good" winding. If not, then rotate the fan to the next "stop" (where you can feel it wobble back and forth - typically 90 degrees from the current position) and try powering it on again. Does it start by itself? If yes, then that winding is good. If not, try rotating it to the next stop again, then repeat test. Do this until you've come back to the position where your marker lines are aligned again.

If there's an open winding, this will be the easiest way to spot it.
And if it is an open winding, it actually could be an easy fix if it's something like the wire just getting detached/broken from its post. The ICs are usually fairly tough in most fans and won't go bad... save for letting the fan over-spin very fast when dusting it with compressed air. I always cringe when I see someone doing that in a video on YT or IRL. Indeed fans should always be held down -by hand- when dusting with compressed air. Making the fan spin very fast from the compressed air will make it generate electricity from its windings... and if allowed to spin really really fast, the generated voltage could exceed that of the driver IC, thus killing it. Even worse, if the fan is attached to a piece of hardware (GPU, motherboard, etc.) you also risk sending the generated voltage back into whatever is powering the fan, which may or may not get damaged if sufficiently high voltages are reached.

Originally Posted by petehall347

its done its job .. send it in for melting down into a new one .

Meh. Recycling is inefficient. Repair and re-use is the way to go... whenever possible and within reason, of course. Sometimes, clearly it's not.
I know these cheap fans and similar hardware aren't really worth spending the time on, as even 1 hour of work at the lowest wage job will often be more worthwhile from a financial standpoint. But then where's the fun in that?! By that logic, almost nothing should ever get repaired. Hell, if only money talks, then I probably wouldn't even wash my dishes and just use paper/disposable ones. In terms of cost for hot water and electricity, there probably isn't much of a difference anyways.