Can this Noctua 12v Fan be fixed? - Page 1
Forum section: electronics / repair

author: enut11
author_rank: Super Contributor
timestamp: July 30, 2024, 08:27:45 am
content: My 120mm Noctua fan died. It was great while it was working, efficient and relatively quiet.Since they are expensive, I decided to have a go at fixing it. There are lots of YT video on fan repairs but when I pulled mine apart I did not see the familiar 3pin Hall chip but rather an 8 pin IC.There are no markings on the chip apart from an embossed square in one corner.Not familiar with Hall chips so looking for tips on how to trouble shoot this circuit.enut11

author: enut11
author_rank: Super Contributor
timestamp: July 30, 2024, 08:35:52 am
content: Powering the PCB from a current limited 12v supply shows up as a short or very low ohms circuit.All the discrete components tested OK. The two coils both tested at around 36ohms so that seems OK.Sounds like the 8 pin chip is dead but not knowing the pin-outs makes it difficult to test further.Any suggestions before I pronounce it dead and unrepairable?enut11

author: RoGeorge
author_rank: Super Contributor
timestamp: July 30, 2024, 09:11:32 am
content: Quote from: enut11 on July 30, 2024, 08:35:52 amIn case you don't find a replacement for the dead component, maybe try to fit an entire PCB taken from another cheap/used 4 wires fan. The low noise of a Noctua comes mostly from the mechanical parts, coils might not be much different from the coils of an ordinary fan. Chances are it might work, but I never tried, only speculating.

author: magic
author_rank: Super Contributor
timestamp: July 30, 2024, 09:44:40 am
content: Quote from: enut11 on July 30, 2024, 08:35:52 amIt's a single layer board, come on. I can figure out most connection even from your photo.

author: enut11
author_rank: Super Contributor
timestamp: July 30, 2024, 09:52:46 am
content: @magic, quite right, it would be relatively easy to trace out the circuit.However, I just found out that Noctua use a proprietary chip in their fans.

author: Runco990
author_rank: Frequent Contributor
timestamp: July 30, 2024, 03:30:15 pm
content: Probably the NE-FD1 IC designed by Noctua. But where to get one?I'd longshot it and re-flow all the connections first. Seen plenty of surface mount bad solder, even if not visibly apparent.Other than that....

author: fzabkar
author_rank: Super Contributor
timestamp: July 30, 2024, 05:14:19 pm
content: https://noctua.at/en/ne_fd1_pwm_icISTM that Noctua's SCD (Smooth Commutation Drive) tech could do with a lot of improvement. Hard drives have been using STMicroelectronics' SMOOTH 3-phase DC motor controllers for decades. This approach is a lot smarter.

author: floobydust
author_rank: Super Contributor
timestamp: July 30, 2024, 06:02:29 pm
content: OP the PCB trace along the outside edge looks quite carved up, make sure it's not open circuit.The IC looks JEITA, it's not an SO-8 with the straight leads and pics of the NE-FD1 are gull wing.Any idea what the SC-70 part number is, what it's doing.

author: fzabkar
author_rank: Super Contributor
timestamp: July 30, 2024, 06:35:44 pm
content: Pic of the NE-FD2:https://www.relaxedtech.com/reviews/noctua/nf-a14-industrialppc/noctua_fd2_ic.jpg

author: enut11
author_rank: Super Contributor
timestamp: July 30, 2024, 09:30:31 pm
content: Quote from: Runco990 on July 30, 2024, 03:30:15 pmYes, it is an FD1 chip. Will try your suggestion on re-flow.

author: enut11
author_rank: Super Contributor
timestamp: July 30, 2024, 09:35:10 pm
content: Quote from: floobydust on July 30, 2024, 06:02:29 pmThe outer track in OK, just my ham-fisted approach to removing the PCB assembly.'SC-70'? not sure what you are asking

author: floobydust
author_rank: Super Contributor
timestamp: July 30, 2024, 10:20:38 pm
content: Quote from: enut11 on July 30, 2024, 09:35:10 pmsee pic

author: thm_w
author_rank: Super Contributor
timestamp: July 31, 2024, 12:14:05 am
content: This fan was released in 2018 or 2019, warranty 6 years, surely it was still under warranty?

author: fzabkar
author_rank: Super Contributor
timestamp: July 31, 2024, 01:05:00 am
content: Quote from: enut11 on July 30, 2024, 09:52:46 amLet me try.I think that IC1 is a 2-phase brushless DC motor driver with on-chip Hall sensor, PWM control input and tacho output.8/ Config / Mode #17/ Config / Mode #26/ Ground / V-5/ V2 -- motor phase #24/ V0 / V+ -- positive supply to motor and PCB3/ V1 -- motor phase #12/ S -- speed sensor output ??1/ P -- PWM input ??I suspect that R2, R3, R4 are configuration or mode select resistors or shorting links.

author: enut11
author_rank: Super Contributor
timestamp: July 31, 2024, 01:15:38 am
content: Quote from: thm_w on July 31, 2024, 12:14:05 amI am not the original owner and do not have the receipt. Also, cost of postage from Australia could exceed its value.

author: enut11
author_rank: Super Contributor
timestamp: July 31, 2024, 01:19:05 am
content: Quote from: floobydust on July 30, 2024, 10:20:38 pmTransistor ID is RKM40

author: floobydust
author_rank: Super Contributor
timestamp: July 31, 2024, 01:48:39 am
content: I meant SC-59 for as a package guess, it seems smaller than SOT-23?SMT marking code "RK" is a hall sensor likeAK1751but "M" is not a valid year code.Or RK7002 but SOT-23.Just looking at other parts that might have died.

author: fzabkar
author_rank: Super Contributor
timestamp: July 31, 2024, 01:52:33 am
content: Quote from: enut11 on July 31, 2024, 01:19:05 amWhat is the circuit reference? Is it a Q or an IC?Does it look like this?https://ae-pic-a1.aliexpress-media.com/kf/S25333058a3724cc9823f87c4c5a7255cc/20PCS-50PCS-100PCS-1000PCS-New-original-RK7002T116-RK7002-MOSFET-N-CH-60V-250MA-SST3-silk-screen.jpg

author: enut11
author_rank: Super Contributor
timestamp: July 31, 2024, 01:56:58 am
content: Quote from: fzabkar on July 31, 2024, 01:05:00 am@fzabkar, looks about right to me.There is 5.6R resistance between 4 (+IN) and 6,7 (Gnd).Pins 6 and 7 are connected together.I found some brushless fan internal circuits to get a feel for how they work. The two 8-pin controllers below have separate hall sensors.

author: enut11
author_rank: Super Contributor
timestamp: July 31, 2024, 02:08:01 am
content: Quote from: fzabkar on July 31, 2024, 01:52:33 amIt's a Q. Similar to your URL.

author: fzabkar
author_rank: Super Contributor
timestamp: July 31, 2024, 02:17:38 am
content: Quote from: enut11 on July 31, 2024, 02:08:01 amThen it's probably an RK7002 by Rohm:https://avtronic.eu/medias/rk7002/rk7002.pdf

author: fzabkar
author_rank: Super Contributor
timestamp: July 31, 2024, 02:27:15 am
content: Quote from: enut11 on July 31, 2024, 01:56:58 amISTM that if V1 and V2 are shorted to ground, then the IC has a shorted internal MOSFET. Is that the case?

author: magic
author_rank: Super Contributor
timestamp: July 31, 2024, 04:14:09 am
content: The discrete circuit seems to short the negative terminal of the supply bypass cap (C1) to ground after a time delay determined by R5,R6,C2. Is it supposed to limit inrush current?At any rate, this part doesn't seem particularly critical and most likely the IC is blown. If R5 measures 3k3 then the supply can only be shorted by the chip or by C1. Easy to check by desoldering C1.edit"Shorted by the chip" could either be internal short between VCC and GND or shorted power transistors in series with motor windings, as suggested by fzabkar. Maybe 5.6Ω is simply winding resistance and the chip has about 0Ω from V1/V2 to GND...

author: enut11
author_rank: Super Contributor
timestamp: July 31, 2024, 05:23:40 am
content: Both R5 and R6 measure 1.65K in circuit.It is a nuisance when manufactures use custom chips, especially in what would otherwise be a valuable and repairable item.

author: thm_w
author_rank: Super Contributor
timestamp: July 31, 2024, 11:21:46 pm
content: Quote from: enut11 on July 31, 2024, 01:15:38 amThey are not going to ask you to mail it back.https://www.reddit.com/r/Noctua/comments/st4vb7/noctuas_amazing_warranty_services_secondhand/

author: enut11
author_rank: Super Contributor
timestamp: August 01, 2024, 06:14:14 am
content: Thanks@thm_wEmail sent to Noctua. Fingers crossed.enut11

author: RoGeorge
author_rank: Super Contributor
timestamp: August 01, 2024, 06:18:03 am
content: Break alegfin!

author: fzabkar
author_rank: Super Contributor
timestamp: August 01, 2024, 05:17:57 pm
content: I would ask them if it is sufficient to remove the IC and crack it in half. The mechanical parts could be useful as spares.

author: enut11
author_rank: Super Contributor
timestamp: August 03, 2024, 05:20:09 am
content: Noctua got back to me in a timely fashion. Unfortunately I voided the warranty by dismantling the unit.Now looking at powering the fan using a HDD brushless motor, maybe...

author: magic
author_rank: Super Contributor
timestamp: August 03, 2024, 08:29:23 am
content: Like, you sent them a link to this thread and asked for a Mouser link to order the chip?Next time simply say the fan doesn't spin and you don't know why, period.

author: DavidAlfa
author_rank: Super Contributor
timestamp: August 03, 2024, 12:03:51 pm
content: Did you check if any of the ceramic caps were shorted?

author: enut11
author_rank: Super Contributor
timestamp: August 04, 2024, 07:27:09 am
content: Quote from: magic on August 03, 2024, 08:29:23 amyes, I fell into that one

author: enut11
author_rank: Super Contributor
timestamp: August 04, 2024, 07:29:41 am
content: Quote from: DavidAlfa on August 03, 2024, 12:03:51 pmcaps are all OK.Noctua do not supply PCB assemblies or controller chips.

author: floobydust
author_rank: Super Contributor
timestamp: August 04, 2024, 07:11:17 pm
content: Send the IC to Noopy to take some die shotsI find if a PWM output is shorted, things get hot so I wonder if something else didn't fail, like the Hall sensor. but not sure where it even is.Noctua latest CPU cooler gen2, after 10 years the NH-D15 G2 retails for USD $150, highest price ever for a CPU cooler. But 6 year warranty. They're now priced like Fendi, Gucci.

author: enut11
author_rank: Super Contributor
timestamp: August 06, 2024, 10:12:34 am
content: The Hall sensor is integrated with the controller chip, usually buried in the center of the face with the ID info

author: fzabkar
author_rank: Super Contributor
timestamp: August 06, 2024, 10:25:20 am
content: Quote from: floobydust on August 04, 2024, 07:11:17 pmThere is a good reason why the IC is installed upside down and pokes through a cutout in the PCB ...For example ...https://www.monolithicpower.com/en/documentview/productdocument/index/version/2/document_type/Datasheet/lang/en/sku/MP6630H/https://www.monolithicpower.com/en/documentview/productdocument/index/version/2/document_type/Datasheet/lang/EN/sku/MP6517/document_id/3762/

author: magic
author_rank: Super Contributor
timestamp: August 06, 2024, 11:24:14 am
content: Quote from: enut11 on August 04, 2024, 07:27:09 amWell, unless you broke something, I suppose you could still put it back together and "gift" it to a friend who would "notice" that his new fan doesn't work and apply for warranty

author: iMo
author_rank: Super Contributor
timestamp: August 06, 2024, 12:19:42 pm
content: After switching PC on my PSU fan started to make an unbelievable noise, with strong vibrations, like when cutting a metal pipe with a dull circular saw. After about 10-20 seconds based on the room temperature it got silent (perhaps stopped turning, no feedback to PC). I operated it that way for many months..Finally I opened the PSU and looked at the fan it (a standard 80mm fan) and found out its bearing was dry but in perfect condition. I greased it a little and since then it is almost noise free (and it blows as it should)

author: floobydust
author_rank: Super Contributor
timestamp: August 06, 2024, 07:36:53 pm
content: Quote from: fzabkar on August 06, 2024, 10:25:20 amI didn't know where ring magnet B-field ends up I'm so used to the Hall sensor being radial inside the ring, not along the edge.Whatever the '7002 is doing makes no sense.Melexis makesUS90AI would stuff one of those in there. Only 4 pins are required. Or theMP6517.I find few IC's have the built-in Hall sensor.For fan lube I use 5W20 off the dipstick if I'm cheap lol.Krytox GPL 105is expensive heaven - it doesn't evaporate, not oil-based and has Teflon, used in space. It seems to be used for keyboard switches too. So far it works the best.

author: thm_w
author_rank: Super Contributor
timestamp: August 06, 2024, 10:39:11 pm
content: Quote from: enut11 on August 03, 2024, 05:20:09 amFor future reference, don't tell the manufacturer you've taken their product apart or modified it in any way when you put in a warranty claim.Unless of course if these were the cause of the failure.

author: fzabkar
author_rank: Super Contributor
timestamp: August 06, 2024, 11:47:11 pm
content: Quote from: floobydust on August 06, 2024, 07:36:53 pmThat was one of my examples, but it's a single-phase BLDC controller.