Quieter replacement for Rotron Sprite SU2A3 - Page 1
Forum section: electronics / repair

author: valley001
author_rank: Frequent Contributor
timestamp: October 26, 2020, 09:19:00 pm
content: Hello all,Continuing with my power supply repair I would like to quiet down the fan noise. I would like to stick with the original specifications of the replacement fan but I can not find any documentation on this model. Also wondering if this is a fools errand in general, do modern fans move the same amount of air while making less noise?Thanks all.

author: DeepLink
author_rank: Regular Contributor
timestamp: October 27, 2020, 12:07:57 pm
content: Old HP T&M equipment can be quite loudI exchanged all my fan's with Noctua modelsThough your model is a 115VAC type, I guess that you can find a low aux. voltage in your supply - like 12 voltThe AC types consumes quite a bit of power(not exact your model)http://www.comairrotron.com/content/sprite-ac-su2b1-19028268aBut look for a Noctua NF-A8 FLXIf the power supply's aux. voltage is to high, either use the supplied "Low Noise" adapter or build a small power supply with LM7812 or LM317In my HP E3634A I build a small regulator with a thermistor, so it is very low noise at light loadAt max load the thermistor senses the heat sink temperature an adjust acordinglyEnjoy your silent power supply

author: valley001
author_rank: Frequent Contributor
timestamp: October 27, 2020, 03:16:52 pm
content: I wonder if this might be an acceptable solution?https://www.mouser.com/ProductDetail/Orion-Fans/OA80AP-11-3TB?qs=oTMpYU8gRs95sYRybmT%252B5g%3D%3DIs 17 CFM enough for a power supply?

author: bdunham7
author_rank: Super Contributor
timestamp: October 27, 2020, 03:37:37 pm
content: Quote from: valley001 on October 27, 2020, 03:16:52 pmThe tubeaxial fans like your Rotron generally have a much higher static pressure capability than the quieter, thinner ones. It isn't just CFM and what you need depends on your design. It isn't easy substituting fans, and if you only use the power supply in moderate conditions, it may well be OK even if the cooling doesn't meet the original spec. For a point of reference, those jet-pack 60mm fans you find in servers put out 50-60CFM and a lot of pressure. So 17CFM isn't that much and if there is any static pressure it will drop dramatically with a 'quiet' fan. I don't know if your fan is just for the heat sink or if there are other components depending on the airflow, so measuring the heat sink temp may be helpful, it also may leave you unaware that some other component nearby is burning up.

author: valley001
author_rank: Frequent Contributor
timestamp: October 27, 2020, 03:52:14 pm
content: Well, maybe id best leave it alone then. My motivation for purchasing the 6038a was to top charge individual large lithium cells so it will get worked fairly hard (though I now find myself looking for a 6033a also for the higher current).I wonder how much of the noise is due to age?

author: bdunham7
author_rank: Super Contributor
timestamp: October 27, 2020, 04:17:28 pm
content: Quote from: valley001 on October 27, 2020, 03:52:14 pmI have an HP8656A RF generator that I fixed and it has a larger 120VAC ball bearing fan and a cooling system that has almost no airflow and needs a set pressure. The fan sounded like an old bench grinder on a bench full of loose tools. The ball bearings felt dry and rough, there was axial and radial play and the blades were chipped. I got a new replacement--same type, impedance protected and all--and the bearings were smooth and tight, perfectly balanced, etc. I put it in and it sounded like a new bench grinder on a bench full of loose tools. Hardly any difference. The installation was like the combination of resonance of a trombone with the soundboard of a cello. To make it worse, this is an instrument that has the fan powered up at all times when plugged in. I can't imagine what it would have been like to work in a lab full of noisy equipment like that.

author: valley001
author_rank: Frequent Contributor
timestamp: October 27, 2020, 04:29:36 pm
content: Quote from: bdunham7 on October 27, 2020, 04:17:28 pmThey probably couldn't hear it through all the cigarette smoke!That's funny about your fan replacement. After I read your post I started listening carefully around my 6038A and I can tell some of the noise is from the sheet metal resonating with the fan! The fan is probably like most of the caps I pulled out, just fine. Its just a noisy beast. My wife says its tenure on the kitchen counter is limited.