Repairing & teardown: IKEA VINDRIKTNING air quality sensor - Page 1
Forum section: electronics / general

author: danchouzhou
author_rank: Contributor
timestamp: December 20, 2024, 02:32:03 pm
content: I bought the IKEA VINDRIKTNING air quality sensor three years ago which can indicate air quality through green, yellow, and red lights. Recently, the internal fan has started making a clattering noise, and the red light frequently indicates poor air quality. However, after checking the air quality monitoring website, the air quality is actually good. I suspect the fan is faulty or the sensor itself has accumulated dust, causing false readings. I decided to disassemble and clean it.After removing the four screws on the back, I easily opened the main unit. Inside, I found an air quality sensor that draws in ambient air through an attached fan. The front has a circuit board that receives data from the sensor and converts it into a three-color LED to indicate the current air quality.From the silkscreen next to the connector, it can be seen that the data transmission between the sensor and the circuit board is through a UART interface.The IC on top of the SOP8 package is the Eastsoft ES7P001FGSA 8-bit MCU.On the other side of the circuit board, there are six LEDs and a photodiode used to detect ambient light and adjust the LED brightness accordingly. Curious about why there are six LEDs for three colors, I powered it on. It turns out that two LEDs of the same color shine on a semi-transparent plastic to produce more uniform light.Next is the main issue to address - the air quality sensor.A plastic bracket combines the air quality sensor and the fan, which can be easily removed from the casing.Flipping to the other side, there is indeed a lot of dust accumulation, so I immediately cleaned it with a brush!The fan is labeled with WANGSHENG DA TECHNOLOGY CO., LTD, and there is not much information available on Google.After removing the two screws on the fan, it came off smoothly. However, no other screws were visible, preventing me from completely removing the air quality sensor from the bracket.To inspect the internal lens, I removed the metal cover and found the circuit board, which has a moisture-resistant coating.The PCB of the air quality sensor is labeled PM1006, an infrared dust sensor by Wuhan Cubic Optoelectronics, capable of detecting particles larger than 0.3 micro-meter.The circuit board is directly mounted on a plastic plate, which can be separated from the casing.Upon separation, it can be seen that the plastic plate also includes a lens, LED, and receiver, with some anti-reflective structures in the casing.The upper left corner has a photodiode (PD), and the upper right corner has an IR LED. They are not directly aligned. When infrared light hits particles and dust in the air, the light scatters to the PD. The worse the air quality, the more scattered light the PD receives, and the PD's signal can be used as a parameter for air quality calculation.An microcontroller which include ADC use to digitize the PD signal, processing it into air quality, and then transmitting it through UART. The microcontroller is a Nuvoton MS51FB9AE - an industrial-grade 1T 8051, with a code memory section called SPROM (Security Protection ROM). It is speculated that the algorithm for converting the PD signal into air quality is stored in the SPROM.Looking at the TRM of MS51FB, the general operation mechanism is that the content in SPROM can only be read when the CPU fetches instructions. Attempting to read the content using a programmer or MOVC instruction, then print it out through UART or other interfaces, will only read zeros, achieving the purpose of protecting key programs, for example: algorithms that are not to be disclosed are suitable for being stored here.The MS51 series was launched around 2019. For new designs, it is recommended to use the newly released N76S003, which also has the SPROM function and is cheaper. The official e-store Nuvoton direct only sales USD 0.22! If a clock frequency of 24 MHz is required, the MG51 series can be selected. For higher performance needs, pin-to-pin replacement with the 32-bit Arm Cortex-M23, M2003 series, is available.Below is a table summarizing the pin-to-pin compatible models. For models with larger memory, there is the MG51FC9AE with 32KB/1.25KB:The other IC on the board is not clearly labeled. It is close to the PD and might be an opamp or analog front end.Now to address the fan noise issue. Initially, I thought the bearing would be like a computer fan, with a cover that can be opened for cleaning and oiling, but it turns out to be sealed!I then removed the cover on the other side. The blades could not be directly removed. Initially, I planned to clean the bearing with stain remover and lubricate it with silicone lube.In the end, I decided to spray auto window lubricant through the holes in the blades, hoping it would help. Before spraying, I cleaned the dust on the blades to prevent it from getting into the bearing.I used this TOYOTA window lubricant, which is manufactured by 3M. The main component is liquid silicone lube. Without removing the blades, it is more likely to penetrate the bearing. Based on past experience, mineral oil (including engine oil, WD-40) can cause the fan bearing to become sticky due to oxidation after a few days, leading to poor operation. Therefore, I recommend using silicone oil (which is chemically more stable and less likely to oxidize) to lubricate the fan bearing.Finally, before reassembling, I reconnected all the cables and tested it with power. The noise indeed disappeared! Now I'll observe the accuracy over time. Thank you for watching!

author: thm_w
author_rank: Super Contributor
timestamp: December 20, 2024, 09:59:16 pm
content: Good repair. Are you using anything specific for filtering?Previous thread:https://www.eevblog.com/forum/reviews/ikea-vindriktning-air-quality-sensor/You can also look at the Vindstyrka, but the cost is much higher:https://www.ikea.com/ca/en/p/vindstyrka-air-quality-sensor-smart-30498239/

author: danchouzhou
author_rank: Contributor
timestamp: December 21, 2024, 07:09:04 am
content: After cleaning and fixing the fan, it works fine. I only cleaned the dust outside, LED, PD & lens looks ok.I actrully bought the VINDSTYRKA smart months ago

author: Simmed
author_rank: Frequent Contributor
timestamp: December 21, 2024, 11:32:21 am
content: Quote from: danchouzhou on December 20, 2024, 02:32:03 pminterestinglooks like PM2.5 sensing ?but no VOC sense ?

author: danchouzhou
author_rank: Contributor
timestamp: December 21, 2024, 04:02:49 pm
content: Yp, no VOC.The new one VINDSTYRKA smart use the Sensirion SEN54 which include VOC indicates.