sub3R wrote: ↑Wed Feb 03, 2021 12:59
... It sounds a touch noisier than the original fan in our 2nd U4 but works fine. It appears to cool slightly better than the original by one or two degrees using the same settings.
Well that replacement fan only lasted from 14-Jan-21 to 23-Mar-22 before it all of a sudden started making a loud screeching noise part way through the U4’s booting cycle with this noise continuing on & off at various volume levels while the U4 was running.
I was never 100% happy with this fan due to it running slightly noisier than the original fan, so I wasn’t surprised that it failed so early. I notice the Beyonwiz shop currently shows the replacement fan as being out of stock.
Has anyone been able to source a decent quality fan to replace these fans?
Not wanting to be without this U4 I decided to see if this fan could be pulled apart, re-greased or re-oiled, then put back together without doing too much damage.
Dismantling & re-oiling/re-greasing the fan.
With the stick-on label gently removed from the fan housing (I re-applied this later, it helps keep dust out of the bush/bearing) it became obvious the challenging part would be to remove the recessed split nylon retaining collar without damaging the collar too much. This collar is just a thin nylon flat washer with a split at one point that allows the collar to expand as it is pushed over the fan spindle into the spindle groove (works like a circlip). The collar is the only thing that holds the two main parts of the fan together (see attached photos).
The first time I dismantled the fan I found the smallest flat blade Jeweller’s screwdriver I had (1.0mm wide) forced into the slot in the collar allowed me to prise the collar off the spindle. This had to be done without too much force for fear of bending the collar too much & possibly cracking the collar.
Before dismantling the fan a second time I decided to make a couple of custom tools to help remove the collar (see attached photo - only one is required). I made these from an old 2.5mm wide x 0.75mm thick stainless steel spline from an SUV rear window wiper blade insert. I ground & shaped the end into a small hook to lift the collar up while spreading the collar at the slot with a 1.4mm wide flat blade Jeweller’s screwdriver. The hole in the plastic fan case is only 4.8mm ID so there wasn’t much room to work.
Looking at the collar after it was removed I suspect a suitable size nylon flat washer with a cut through the washer at one point with a hobby knife could be used if it became damaged too much, but sourcing such a small washer could take some doing. The nylon collar measured 3.5mm OD x 0.4mm thick with an ID of approximately 1.3 to 1.35mm. The spindle measured 1.95mm OD & the groove in the spindle measured 1.3 to 1.35mm OD x 0.5mm wide.
With the collar removed, the fan blade assembly containing the magnets & spindle could now be easily pushed out of the fan housing. The bush the spindle runs in appeared to be a bronze or brass bush (hopefully sintered bronze) that was quite free of any oil or grease but was somewhat dirty.
Long before these fans were in use, the Swedish ABU fishing reel company successfully used sintered bronze bush/bearing instead of stainless steel ball races in their cheaper model ABU Ambassadeur Classic baitcaster fishing reels. These bush/bearings are required to be very lightly oiled every now & again with the porous sintered bronze bush/bearings retaining the oil. The spool on these reels typically revolves at tens of thousands of RPM when casting heavier lures.
Hoping the fan had a sintered bronze bush/bearing of reasonable quality I decided, after thoroughly cleaning the bush/bearing & spindle with 100% Isopropyl Alcohol, to apply a small amount of Tri-Flo Lubricant to the bronze bush/bearing (Tri-Flo is made in the U.S.A, contains Teflon [PTEF] & is rated at -60ºF to +475°F – available from most bicycle shops). Tri-Flo Lubricant is only a very light weight oil.
Not being sure if this fan had a sintered bronze or a brass bush/bearing, I also applied a very light smear of Starbrite PTEF Marine Formula White Teflon grease to the spindle (This is very light grease & is supposed to be impervious to salt & fresh water, highly lubricious, & rated over a -65ºF to +650ºF temperature range – available from Whitworths Marine). I’m in two minds whether adding the Starbrite Teflon grease will work for or against.
Re-assembly was straight forward & easy. So far it is quieter & acceptable for this low quality fan, but whether it stays that way remains to be seen – if it doesn’t I’ll post back. Reports of success rate on the internet range from very short term to long term for re-greasing or re-oiling computer cooling fans. I hope I have re-oiled it before too much wear has taken place.
For anyone wanting to tackle this repair, I suggest in addition to 1.0mm & 1.4mm wide Jeweller’s flat blade screwdrivers; a Jeweller’s loupe, a pair of small needle nose pliers used for electronics work, size No.1 & 2 Phillips head screwdrivers, & a small brush for removing dust from the fan blades. If the nylon collar gets damaged beyond repair, Vernier Callipers would be required to measure for a suitable nylon washer.
Note that the measurements given above are for the replacement ‘QG Hong Xing Shu Electronics Co.’ fan I previously purchased from the Beyonwiz shop. I don’t know how the measurements of the original factory fitted fan compares.
Most of the attached photos are fairly poor quality, but the hopefully they show enough detail.
- Nylon collar in place on the spindle.
- Bush/bearing after removing the spindle.
- Spindle showing the groove for the collar.
- Nylon collar.
- Suggested tools.
- Tri-Flow & Starbrite PTEF grease.
- Nylon collar removal tool.
