Fans and fan connectors on a RaQ 3 and 4

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Too much about fans

If you have powered up more than three RAQs, you've probably encountered a bad fan. It's pretty important to change bad fans out as they will lock up sooner or later and stop circulating air.

The RAQ 3 and RAQ 4 use a small 12 VDC fan that is 35 mm square and 10 mm thick. This is an industry standard dimension so there are lot of parts from a number of suppliers that will fit in the hole. The original fan is a Sunon KDE1235PFB1-8. This is a ball bearing fan that is rated at one watt of dissipation and will move about 5-7 CFM of air under ideal conditions. There is a lower speed version that will move 4.5 to 6.5 CFM and is slightly quieter. It has 'locked rotor' protection - meaning that if the fan blade is blocked from moving the fan will not execute a 'halt and catch fire' operation. Almost any manufacturer's fans will provide similar air movement performance for one watt of dissipation in this package. The one odd fact about the Sunon package is that it only provides three mounting holes where the industry standard is four. This is not a problem if you need to use someone else's fan with four mounting holes. Almost all of the fans in this size only support the motor and blades from one side. This is the side that goes against the chassis. When you install a new fan make sure that your fan lines up cleanly and doesn't block any of the air holes at all. There is so little area here that you don't want to lose any.

Changing Fans

Crimping the Fan Power Connectors

I use an AMP Special Service Tool I which is an inexpensive (relatively) non-ratcheting tool. It's not the correct tool, but it's close enough. Since the fan lead wire is so small, I strip the wire twice as long as I need and fold it back on itself. This makes for a more reliable connection. If, like me, you aren't using the recommended tool, crimp the wire portion of the contact separately from the insulation clamp. Before I crimp the insulation clamp I usually do a gentle pull test of the wire crimp to insure that the mechanical contact is good.

Changing the Power Supply Fan

The power supply cover is held in place by a single screw near the secondary hard drive bracket. Most of the screws in the cobalt are Phillips head (or some variation of cross-point.) The power supply cover screw is a T10 Torx® head screw which is unlike most of the others. Once the screw is removed the cover slides forward slightly and can be lifted out and laid on the secondary hard drive.

NOTE: After you swap the fan use care in replacing the power supply cover because the notch the fan wires run through is small and it's hard to not pinch the wires.

Changing the CPU Fan

The CPU fan is pretty straightforward. Gently work the plastic air guide the out to expose the fan. It takes a little jiggling to get the fan out, but it comes out without removing the motherboard.

Fan Mounting Screws

The fan mounting screws on the RAQ are self tapping. All of the other case screws are threaded. The cover and rack bracket screws are of a similar size and are black as well. DON'T MIX THEM. If you use the fan screws on the cover, they'll work, but they will damage the threads and you can't go back to the correct screws. The cover screws will not mount the fans reliably.


Ball Bearing vs Sleeve Bearing vs Magnetic Levitation

Generally you can assume that ball bearing fans will run quieter and longer than sleeve bearing fans. In these really small fans I'm not sure you'll notice the impact. There is probably some noise improvement, but it's probably not significant. Sunon calls their sleeve bearing "Vapo Bearing." Like most all fans in this class the sleeve is lubricant saturated and the lubricant is actually supporting the load.

Sunon also offers a newer product line they call the "Maglev" that uses the same package. Magnetic bearings are ideally frictionless and so don't wear out. The Sunon Maglev fans are available in both ball and "Vapo" (lubricated sleeve) bearing models. Strictly speaking these brearings would only be used for startup, but I have no information to support that assumption and suspicions to the contrary. The only Sunon catalogs and data sheets I have are thin on technical details, particularly in the area of reliability.

In summary I can't tell you it matters much. There are certainly differences between vendors and designs, but I have no documentation that supports one selection over another.

Reduced Noise

If you are running a RAQ in a location where cooling isn't a problem but noise is, use a lower power fan. Again, Digi-Key stocks lower power (wattage) 12 VDC fans. The blades will turn slower and be substantially quieter. If I were doing this, I'd monitor the CPU temperature and power supply exhaust temperature for a bit to make sure it's all keeping cool enough.


The fan connector is a Molex 6471 series shell, Molex P/N 22-01-2025 which Digi-Key stocks under catalog number WM2613-ND. If you are replacing the fan you'll probably be able to reuse the connector body and only need contacts. There are two slots in the connector body that the contact locking tabs fit into. If you insert the end of a small paper clip or pin in the end of this slot closest to the wire side of the connector you can pull the wire and contact out of the connector. Digi-Key stocks Molex 08-52-0123 contacts for this connector under catalog P/N WM2758-ND. There are a bunch of different contact materials and plating options. There's literally no value in gold plating in this application. The posts on the RAQ motherboard are tin and the current is high enough that tin works just fine. If gold is all you can get that's fine, it's just a waste.

If you have access to an electronics parts supplier of substance, They probably have these as a "Waldom" parts and I believe the Digi-Key catalog numbers correspond to the Waldom part numbers.

If you aren't worried about pretty, cut the old wires at the fan and splice the old and new wires matching their colors. I'd use a "B Wire Splice." They are fully insulated, easy to use, and hard to mess up. Strip the wires back a centimeter or two, stuff them in the splice, and mash it with a pair of pliers. My Home Depot stocks these with the telephone and CAT5 cable parts.

== Catalog Numbers and Prices== as of August, 2008


Catalog No.     Description                             Price   U/M
WM2613-ND       Molex 22-01-2025 Connector Shell         0.39   Each
WM2758-ND       Molex 08-52-0123 Contact                 1.34   PK/10
P12811-ND       NMB 35mm BB Fan 1404KL-04W-B50-B00      14.13   Each
603-1128-ND     Delta 35mm BB Fan AFB03512HA-A          12.72   Each
259-1391-ND     Sunon 35 mm SB Fan GM1235PFV1-8.GN      15.39   Each     See Note: 1
BB= Ball Bearing; SB = Sleeve Bearing
1 This is the Sunon 'Maglev' fan - supposedly better reliability and quieter


Jameco P/N 212759 is SUNON P/N KDE1235PFB1-8 (the precisely correct original part number) Price as of Aug 2008; 1+ 11.95; 10+ 10.75; 50+ 9.69; 100+ 8.69

--ozindfw 19:32, 02 Aug 2008 (PDT)

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