noctua Fans swap -  4 pin PWM in 3 pin socket -  possible? - Page 1
Forum section: electronics / beginners

author: lots o tots
author_rank: Contributor
timestamp: August 01, 2023, 02:25:50 pm
content: I have a video light I want to swap a new fan that is quieter. I have seen others online fan swap, but all of them have increased temperatures because the fan they used has insufficient airflowAs of their board temperatures have all increased. The old fan is a PD922512MB-03 that has 3 pins. no information is available on static pressure from what I can find.On the Noctua website for 92 mm fans, the fastest 12 V fan 3 pin is only 1600 rpm. They do have a version that is 2000 rpm that is PWM 4 pin, which closely matches the airflow specs Of the stock fan better than the 1600 rpm fan. I could not find a fan from any other manufacturer with better specifications on airflow and static pressure while maintaining a reasonable noise levelhttps://noctua.at/en/products/fanI don't mind if the fan runs at 100%.can I cut the fourth pin wire from the fan and not use it? ( is this possible)Will the RPMs decrease as a result of thiswill there be any negative feedback to the device may be causing flicker or some other unintended consequencesare there any unforeseen reasons I have not listed of why this can be donethank you

author: jmw
author_rank: Frequent Contributor
timestamp: August 01, 2023, 03:04:55 pm
content: Is this what you're trying to do: replace this fan (https://detail.1688.com/offer/568786210232.html) with this (https://noctua.at/en/products/fan/nf-a9-pwm/specification)?The holes won't line up, so that's a non-starter.Might heed the warning at the top of this video too,https://youtu.be/LTuJxckPNp8- the guy no longer recommends a fan swap despite having made a slick video on how to do it.

author: lots o tots
author_rank: Contributor
timestamp: August 01, 2023, 04:13:40 pm
content: Quote from: jmw on August 01, 2023, 03:04:55 pmthanks for looking that upA few things to fill in the gaps:The person in that video is using 150 W light, rather than the 100 model which is what I have.I believe the same fan was used for the 60 Watt, 150 Watt, 100 W models. his cooling options were limited entirely. Also in terms of lining up, the old fan is round and 92 mm with 80 millimetre mounting holes. if I were to choose an 80 mm fan even with sufficient airflow, not covering the entireHeat sink surface area significantly reduces performance. Think of a square peg in a round hole literally. The solution to the problem from what I can see is to use the proper 92 mm fan and take that fan to my scroll saw or bandsaw and cut a round shape ( removing any flanges except for a tiny area). any errors I make in dimensionsOr mounting hole locations will be fixed and cured with plastic epoxy ( not hot snot)And drilled! before fitting in hole.it is a lot of work, but I don't want to return this to Amazon unless I absolutely have to.Bottom line is I think I have the met mechanical part sorted, but the electrical part still unknown to me.

author: MLXXXp
author_rank: Frequent Contributor
timestamp: August 02, 2023, 12:19:42 am
content: The 4th fan wire is for controlling the speed of the fan using pulse width modulation (PWM). If you don't connect it, the fan will run at full speed.So, if having the fan run at full speed is okay for you, and you can make the remaining 3 fan wires connect to the wires of the light, it should work.And actually, the 3rd wire is an output from the fan that provides a frequency proportional to the speed of the fan. If your light doesn't need this to monitor fan speed, you would only need to connect the first two pins (ground and power).

author: lots o tots
author_rank: Contributor
timestamp: August 02, 2023, 02:48:57 am
content: Quote from: MLXXXp on August 02, 2023, 12:19:42 amAwesome I was concerned the fan speed would decrease or some other issue caused. I was mostly concerned about this causing flickering.I was going to purchase separate JST connector rather than splicing into the light but wasn't sure which size