Meanwell RS-15 series: Change voltage? - Page 1
Forum section: electronics / projects

author: 0xFFF0
author_rank: Regular Contributor
timestamp: November 21, 2023, 10:04:19 am
content: Does anyone know whether the Meanwell RS-15 series can be converted, i.e. changing the voltage with a different Zener? Is there a circuit diagram somewhere?

author: Doctorandus_P
author_rank: Super Contributor
timestamp: November 21, 2023, 11:02:00 am
content: Like most of the power supply bricks in shiny perforated metal form factor, these also have an adjust potentiometer for the output voltage.https://www.meanwell.com/Upload/PDF/RS-15/RS-15-SPEC.PDFSuch power supplies are generally also quite easy to reverse engineer. Increasing the output voltage is probably problematic, you may get into troubles with saturation of the transformer, or a reduced input voltage range, but it is quite wide for these power supplies. 85 to 264Vac, or 120 to 370Vac.The bigger power supplies often have a small auxiliary SMPS for powering the internal circuitry, and that makes it easier to make some custom output voltages. If you lower the output voltage, then some internal circuitry may not get enough voltage anymore.I do not know what is inside this series, but I assume they are relatively simple. After all, you can't put much electronics in a EUR10 power supply. On pictures I also see a yellowish PCB, which implies FR2 and single sided, which is also common for this type of power supplies. I am in doubt what sort of advise would be applicable here. If you have some decent experience, I'd say just buy one and try it out. Be careful around it's limits, and do some testing to make sure you don't go over limits. Things like over / under voltages or currents, saturation effects and loop stability. But if you have a decent amount of experience with electronics, you probably would not be asking here.If you are a beginner with electronics, then you probably should not even open the thing, and certainly not attempt modifications.

author: coromonadalix
author_rank: Super Contributor
timestamp: November 21, 2023, 11:08:50 am
content: They are more than a simple zenner ... they normally use dedicated ic's, even at this low pricesThey are switch mode power supply

author: Buriedcode
author_rank: Super Contributor
timestamp: November 21, 2023, 07:47:29 pm
content: The voltage in these PSU's can be varied *slightly* around the specified output voltage, but it isn't much perhaps +/-10%. As they are designed for a fixed output rather than a range, the transformer will have inductance and turns ratio optimised for that output voltage and the duty cycle the converter uses to generate it. Messing with the feedback network in these would likely change its output current capability and probably its stability.So short answer: yes, but not much by at all. Long answer: Not really, but you could always add a buck/boost converter after it - it'll hit the efficiency but for low/medium power its an option.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 21, 2023, 07:59:55 pm
content: Small changes are easy, just find the feedback divider which is two resistors in series from output to GND, with middle node going to one of the switcher IC pins. Parallel a very large value resistor with either one of the two, to adjust the value slightly. But as pointed out above you can't trust you could go beyond maybe 10% adjustment. Nevertheless, I have turned random 12V and 16V supplies into 13.8V.

author: wraper
author_rank: Unknown
timestamp: November 21, 2023, 08:12:02 pm
content: There already is a potentiometer for about +/-10% adjustment (a bit more in practice). You probably can push it somewhat over that range. But without rewinding the transformer not by much because PWM controller power will go out of range and its protection will kick in.