Electronics > Repair
Can this Noctua 12v Fan be fixed?
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enut11:

--- Quote from: floobydust on July 30, 2024, 10:20:38 pm ---
--- Quote from: enut11 on July 30, 2024, 09:35:10 pm ---The outer track in OK, just my ham-fisted approach to removing the PCB assembly.

'SC-70'? not sure what you are asking

--- End quote ---

see pic

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Transistor ID is RKM40
floobydust:
I meant SC-59 for as a package guess, it seems smaller than SOT-23?
SMT marking code "RK" is a hall sensor like AK1751 but "M" is not a valid year code.
Or RK7002 but SOT-23.
Just looking at other parts that might have died.
fzabkar:

--- Quote from: enut11 on July 31, 2024, 01:19:05 am ---Transistor ID is RKM40

--- End quote ---

What 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
enut11:

--- Quote from: fzabkar on July 31, 2024, 01:05:00 am ---
--- Quote from: enut11 on July 30, 2024, 09:52:46 am ---@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. :(

--- End quote ---

Let 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 #1
7/ Config / Mode #2
6/ Ground / V-
5/ V2 -- motor phase #2
4/ V0 / V+ -- positive supply to motor and PCB
3/ V1 -- motor phase #1
2/ S -- speed sensor output ??
1/ P -- PWM input ??

I suspect that R2, R3, R4 are configuration or mode select resistors or shorting links.

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@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.
enut11:

--- Quote from: fzabkar on July 31, 2024, 01:52:33 am ---
--- Quote from: enut11 on July 31, 2024, 01:19:05 am ---Transistor ID is RKM40

--- End quote ---

What is the circuit reference? Is it a Q or an IC?

Does it look like this?


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It's a Q. Similar to your URL.
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