Initially I just wanted to have an occupied signal for a bathroom in a shared flat the fan is installed in. Thing is, I had no PICKit in 2022, so I eventually decided to cut power of MCU: I realized I was going all in, a replacement MCU was needed.
I hope this write up helps somebody repairing their PCB, provides an easy start for modifying or is at least a pleasant nice2read.

I am aware that Maico offers interconnected fans and aftermarket PCBs (e.g. ECA ipro RC(H)) - it is just not what I was looking for.
It was supposed to be “smart”, but what does “smart” in this case mean? To me, a well suited solution (for a non-smart-home shared flat). This is a personal use project.

After some drifting off with my thoughts, what I came up with was:

• have an occupied signal¹
• get rid of annoying, timer based only trigger²
• light switch toggle to turn fan on/off for 💩-mode³
• turn on fan on high humidity⁴
• easy way to configure: cloudless WiFi webpage interface⁵
• night mode (gets time via NTP)
• stopwatch pee time game for fun⁶

Read on but don't let the 💩 hit the fan! (no pun intended) - take care.

Not a real disclaimer. Think. I am not responsible of what you do. This is for educational purposes out of curiosity only.

⚠️ The PCB is connected to mains 230VAC! Be aware of what you do. This is no kids game, it can be life threatening or worse if you are not careful.
I am not responsible for anything you do, this is not meant to be a tutorial to mimic. It is just a write up of the steps I have taken to achieve a goal I have striven for.

Link to original manual
If you feel not comfortable with a repair, get original ECA100 ipro VZC circuit board for 73€ with cover and 81€ with pin header for sensor. 🧂

The fan consists of a 1-phase AC motor, a PCB controlling it and the shell/casing.
Unmodified ECA 100 ipro VZC series has the following hardware on PCB:

MCU: PIC16F677 -I/SS
AC/DC: LNK304DN
Optocoupler: P185
Triac: ST T405Q 600

varistor: S10K275
input cap1: 400V 4.7

On some PCBs it's nearly impossible to read part numbers on the backside of PCB as the high voltage portion on the backside is painted in clear protective glue(?). For measurements I have just scratched it. Remember to melt the glue to close up the scratches again.
The backside of the PCB has unfortunately no silkscreen, that is why I have made up names for test points, e.g. ACF (=AC Frequency input)
I have quickly ordered all parts in KiCad according to PCB layout - (Yes, I am well aware that schematics are normally not drawn like that. It is only my shared notes; if you want to pick up on them and create a board layout, go for it :)). It might contain errors, I actually haven't checked.

Tldr schematics; LNK304 provides 5V power with opto-coupler as feedback. Resistors scale down voltage for AC-wave signal, which is fed into PIC16 via transistors. PIC16 triggers Triac (according to AC-wave).

schematics without MCU
Download KiCad (>=v6) schematics, complete with PIC16 pinout: Todo <insert schematics>

Interesting is that the Triac switches Neutral, not Live conductor: in my world that is considered bad practice. Is there something I do not see here?

Pinout of PIC16

for better (test) pads, see later photo and newly created PCB scan :)

The Triac is triggered by PIC16 synced to AC-wave signal (provided by opto-coupler). Triacs do not turn off automatically again if fired, unless voltage drops to 0V (or complicated circuit added). So what you see on logic analyze capture is just the triggering signal for Triac (D0), not its durance it is turned on. The durance is the point the Triac is triggered till signal of opto-coupler (D1) is low (and therefore AC-wave crossing 0V).
The fan has originally only two speeds, configurable via jumpers: slow (78m³/h) and fast (92m³/h).

In 2025 I got hands on a broken PCB (due to water damage) on Kleinanzeigen, more than three years after the start of the project. I desoldered all parts and scanned the PCB for your convenience. I did not have any solvents but acetone nail polish at hand, which does not work that well with the sticky glue. What I did is heat the glue with hot-air rework station and wipe most of it off with a cloth - the mite rest was removed with acetone (nail polish).

#TODO: add size measurements of PCB! in scan+text

I admit, I have not cleaned the board properly, as it was corroded and toast anyways. The trace of L-line was burned up of this broken PCB, I have redrawn it in pink to show the original trace.
According to the datasheet, the PCB is 18 x 20 x 125 (Width x Height x Depth in mm) in size. To me, the depth would rather be the height.
Thanks to the PCB scan, you can see the needed points easily where to solder the wires to for modifying the hardware.

The broken board I got from Kleinanzeigen has (at least) burned Varistor (VDR1) and capacitor C1. Check for burned through PCB traces and replace those two parts.
Also try disconnecting the original sensor (if your version has one) - the humidity sensor I got bundled with is bad too.

Together with the broken PCBs, I got a humidity sensor (which I did not have at the time of the project). The sensor is glued into a plastic shell, the glue looks to be the same as on the backside of the PCB.
The plastic cover of the housing has a rubber cover, which is cut open if a sensor is installed. Tip to close it up again: put crepe tape over the hole and close up with hot glue from the other side.
#TODO: #TBD insert pinout + resistor values
communication protocol / find out sensor type?
worth the hassle?

Don't have a sensor (version) like me? Read on. I have replaced it with SparkFun HTU21D sensor.

#TBD As I now own a PICKit (I have not at the time of doing this project), here is the firmware dump of a PCB with humidity sensor: <insert dump>.
I do not know if firmware differs for models w/o sensor, as the original PCB is still doing its duty in the shared flat. My guess: probably same firmware; the pin header is unpopulated.

⚠ Always make sure casing of electronics is sealed against moisture properly again! The PCB-scan shows what happens if not. 240VAC ⚡ water 💧 = 🌋 magic smoke 💨 or 🧯🔥. Keep in mind that mains part of PCB is painted with some glue on the backside for a reason.

MCU replacement: cut traces of PIC16 (at least pins 1,2,3 and 17) or desolder completely.
See the photo for a suggestion where to cut traces carefully. This is only reversible if you fix the traces. Scars will be left, do not burn any SMD-caps.

The following hardware modifications will be done:

ESP8266-12F for WiFi
↳ needs LNK306DN buck converter upgrade!
ASM1117-3V3 LDO module (5V to 3.3V)
Humidity+Temp sensor (HTU21D)

Why ESP8266? Because:

1. it has WiFi and sufficient GPIOs
2. peak power barely fits output limit of LNK306
3. it fits physically into the original housing as PCB-sandwich
4. it is what I had lying around in 2022 and was cheap (~1.3€)
5. there was no ESP32 C-series in '22

To squeeze in all that hardware, build a sandwich with hot glue as sauce between the layers: 🥪

• ASM1117-board fits on the front side below the buttons (I admit, it is necessary to grind off a bit at the edges to not be longer than PCB). Requirement: Pin headers for original sensor needs to be unpopulated (desolder otherwise).
  
• Solder SMD resistors directly on the underside of ESP8266-12 (see picture closely), so no space is wasted.
  
• Add humidity sensor breakout board in the plastic cover of housing (HTU21D fits nicely after slicing in the hole for the rubber of the cover). Why HTU21D? Because I had it lying around. There are other sensors which would fit too, e.g. SHT30/31, AHT20/30, Si7021, BME280, etc. Check measurements if the breakout board would fit.
  

#Note: modern way would be to use a RISCV-MCU board with ESP-IDF. ESP32-C3 / C6 super mini should fit the space too. There was no C-series when I have done this project.

⚠️ ESP draws way more power than PIC16: It is mandatory to upgrade LNK304DN to LNK306 for sufficient power! There are pages with current measurements, e.g. for ESP8266 here.
If you have no SMD-rework station, desolder pins one by one by bending each pin up - alternatively cut pins with a rotary tool carefully. Drop and solder in LNK306 as replacement IC.

See schematics on letscontrolit.com/wiki for ESP-12 module to connect needed resistors. If you solder one side of SMD resistors directly on the pad of ESP12 underside and the needed wires on the other side of the resistors, no space is wasted (see 1st pic, magnified). Consider fixing resistors and wire joint with glue, I have chosen UV-glue. Unfortunately, I have not taken a photo of that. Now make the sandwich:

🥪 prototype setup

⚠ Remember: NEVER solder rigid cables onto SMD pads like TestPoints! The leverage is high, so is the danger to rip off the pad - use flex cords.

⚠ take some sandpaper and make PCB a smidge narrower with round edges so no wires are accidentally squeezed
Keep everything isolated AFAP and/or add prophylactic isolation

See PCB scan where to solder wires for FAN, ACF and Light-signal
You might want to cut traces of jumper pins and misuse the 4-pin header for UART (VCC, RX,TX, GND) to easily flash - mark it »no jumpers!«
Repurpose existing buttons by connecting them to ESP for GPIO0 flash-mode and reset pin.
I have not connected the LEDs, as there is a webpage for configuration. You might use GPIO# 1,2,15, which are still unused.

To install the humidity sensor, I have cut a small hole of the size of the sensor IC into the rubber.
⚠️ Seal rubber of housing cover when installing humidity sensor with hot glue! No moisture allowed on the PCB, this is still mains AC! ⚡

#TODO: make and insert photo of humidity sensor rubber

Note: wake from deep sleep is only possible if GPIO16 timer is connected to RST. Otherwise Reset button has to be pressed (which better is wired to one of the buttons on the Maico PCB) or turn AC-power off+on.

This project started as a quick way to improve the fan in a shared flat (which I actually do not live in), I started it with an old POC uni-project using Arduino. Oh, well, there is always a next project to avoid Arduino again. I talked myself into believing I wanted it to be maintainable by another person in the flat. Also, this was my chance to use something else than FreeRTOS and see what people always talk about being done with Arduino - let's see for ourself.

For initial flashing you need a UART-USB adapter (USB to TTL converter), e.g. CH340, CP2102 or similar.
⚠️ Do not power PCB by AC for flashing. Mains Voltage is dangerous for you and your computer! Always use VCC of USB-adapter.
Later on you can use OTA for flashing (unless/until you screw up)
For easy development I have used a Wemos D1 Mini ESP8266 module.

#Note: the modern way would be to use ESP-IDF with an ESP32 RISCV-MCU, like C3 or C6. There was no C-series in '22.

Update ESP8266 Firmware either via ArduinoOTA or upload firmware image on html-page /ota-update. Html is embedded in firmware (together with network AP rescue page) so it still works if there are no pages in FS.
Output binary files of Arduino can be found in some temp directory, which are used to flash on html-OTA.
Use esp8266littlefs-plugin to upload .html files to LittleFS - (tutorial e.g. on randomnerdtutorials.com).
See button config how to put ESP into ArduinoOTA mode.

The buttons on PCB are repurposed:

• right button = RESET| reboots/wakes the ESP.
• left button = puts ESP into Flash-mode if RESET pressed together with it.
• left button function no.2: To go into OTA-mode for ArduinoOTA, RESET then wait ~2s and hold left button till connected to WiFi [~ a few seconds]
  • #TBD: #Todo function no.3: left button for WPS
    

The ESP8266 has two hardware timers: Timer0 is already used for WiFi, making only Timer1 available for user-defined timer interrupts.
We need an interrupt to detect AC-wave signal and could use another timer-interrupt to generate a signal to trigger the triac for the motor, which makes two interrupts - with only one(!) left.
Sure, doing time measurements in code would work, it seems not very elegant with an async webserver. The clever trick is that we do not need the interrupts concurrently for AC-wave detection and motor triac-firing. As the TRIAC is only triggered when AC-wave signal is high, we can use Timer1 for both two interrupts by switching it back and forth between AC-wave and motor signal generation.
Now 💩 really hits the fan: 1+1=3, Problem solved ?:) The nice way? I think it is a well thought way, you decide.

Side note for the reader: A TRIAC can only be turned on by the gate, not off. Once triggered, it remains on until the current through it drops below the holding current—usually at the AC zero crossing.

All signals have been verified with a cheap ~5€ usb-logic analyzer and output with an oscilloscope (thanks for the good old Fluke, dad! O:-)

The two buttons on PCB are already in use, the third “button” is the connected light switch to L1 (see Maico manual how to correctly connect light switch/bulb to L1-input of PCB).
This is so obvious that I do not know how this could have been missed in the first place - sorry. I know, it is bad on the light source, but still. I will rather replace a worn cap in the LED light bulb than miss this function. (No light bulb harmed yet [~3 years], AFAIK).
So simple: toggle the light switch on+off to change mode. I have recently seen it in some Philips(?) ceiling light for changing light color temp, too.
The MCU detects if the light switch is toggled within a specified time. It puts the fan into “kack” mode (read next chapter). Toggle again to turn if off again. You can configure actions however you want on settings webpage. This way you do not even need to bother to take your phone out to control fan over the web interface or smart home function.
How is it done? First of all, both interrupts (even 1+1=3) are already taken. So we need to use polling, which is fine, as it is not time critical, just an informative input signal. The light input signal is an AC-wave switched binary logic signal, so you have to consider that the light has to be turned off/on for so long that it definitely hits the positive AC wave. A duration between two light switch toggles of at least ~100ms is advised (which is perfectly fine, you just have to know. Set maximum interval toggle duration in web-settings).
💞 This is the most loved function of the fan in the flat (next to humidity).
💡 With added bonus functionality to see on webpage if light is turned on, it is my all time favorite and has kept me from some cold feet in the past.

There is another awesome use case for the light switch when some small circuit is added. Just a teaser for now, I will have noted it in the future @Ideas&USPs

As ESP8266 has WiFi, let's use it for a nice local web interface. No cloud, no gateway. For simplicity it runs on Arduino. You might believe it or not, this has been started as a simple project. Let's go in and out. Twenty minute adventure. I have started with a non-async webserver taken from some old and simple POC uni-project. I switched to ESPAsyncWebSrv-lib, a switch I should have made sooner (and what about to step this project up away from Arduino? Meh, 'works on my device, can always port to IDF later 🤡).
The values of the variables in firmware are synced with html using javascript and AJAX with JSON format. Why? I made all this without AI in 2022 and chose what seemed to suite best. It is nice that some of the “workload” is on the end device.
CSS is (unfortunately still) in html as <style> section.
#TODO: separate html,css,js

So the bidirectional communication from MCU to web can be shown as:

MCU with async webserver ↔ AJAX/JS ↔ html

There are four webpages: 1) index 2) settings 3) network 4) webOTA

If WiFi is unable to connect (e.g. on first start), ESP is put into access point (AP) mode. Connect. Because going to 192.168.4.1 to change SSID+password is unintuitive, an AsyncDNSServer creates a captive portal, redirecting to /wificred as AP default page. On this page, configure network settings (mDNS-name, IP) anytime.
Default mDNS-name is: kacken.local/. Better change name to fan.local/ or something more public suitable. .local is fixed by mDNS. (Use your openWrt router to change e.g. to .wg [WG=WohnGemeinschaft; shared flat in German]).
There is a small version of this page embedded in firmware, so it is always possible to connect (and use webOTA too) if something is broken.

#TODO insert AP.html screenshot

Current time for index web page is fetched over internet via NTP. It is used for night sleep mode / power saving interval. By design ESP8266 can only be woken from deep sleep by reset and timer (if GPIO16 connected to RST). Otherwise use light sleep only for power saving.

#TODO insert index.html screenshot

The fan can be controlled via a simple html-button. Date&Time from NTP fetch is shown on html-page for convenience.
The status of the light is shown together with a timer to see for how long light is on (positive minute counter) or since when it is off (negative minute counter). Please do not misuse it for stalking or something alike. Use it to estimate if it could still stink 💩.
The stopwatch time of pee game is shown on the bottom with trophy 🏆
Clicking on the blue info ⓘ starts a 30s countdown js-timer for washing hands (remember to keep your phone clean too).
One to two live changing unicode symbols are shown in big (for fanciness), representing if light is on and the current mode the fan control is in.

There are several 'modes' implemented the fan can be run in. Defined by

1. timer (original PIC16 function replicated)
2. high(er) humidity
3. light switch toggle, aka 'kack' mode → #rename to “power” mode

Unicode symbols are used to show modes and status on the webpage looking neat, modern and easily readable.

There are GET commands (REST) to control the fan too.

/kacken: puts fan into fast mode for configured time
/aus: turns fan off. will be overridden on changed mode
/peestart: starts peeing game
/pissoff: stops stopwatch of game

Go to /settings to change UI controls, light switch, humidity and fan specific behaviors.

#TODO insert settings.html screenshot

All settings are explained by mouse-over tooltips and are clickable on smartphone.
Maximum run time can be set for safety precaution - this time is reset on mode change.
Don't forget to set your pee fan timer.

All configurations and settings are stored in flash (LittleFS) with .ini-format. This includes your wifi password, which sits there unencrypted (but then, you are inside the network already anyways). Do not initially create the save-files, they are created automatically by firmware.

As seen in the screenshot, I have used the word “kacken” a lot, which is informal German for “(to) poop”. The initial project name was KackenESP and that's what it still is. I like the emoji 💩. The implemented “kack mode” turns the fan to high speed for a set time, either by html-button or light switch toggling.
https://www.youtube.com/watch?v=cM-lJP3g9e8
It is just a bad and honest name for a function to turn on the fan, get over or #rename it. It is meant in the natural way: we all have to poop. A good naming substitute may be “power”?

webOTA has its html-page embedded in firmware. There are no checks for anything. Be aware of what you upload/flash, you can break it, connecting UART-cables for flashing might be tedious when fan already installed. There also is ArduinoOTA != webOTA. Read OTA section above.

So what's that now? Relax, nothing kinky. It's a time based fun which was played in the shared flat and IMO deserves its own headline: There never has been a name for the game, I had to give the variable some name and chose “pee_time” as it fits flat, (bad reference jokes to π were omitted).
Are you quicker (with washing hands thoroughly!) than a predefined time (~1min)? Turn light on, do your small duty and turn light off again. If you are too slow, the fan spins shortly to acoustically signal that time has passed and you have lost! Check your time on the webpage - you can start+stop the stopwatch game there too (alternative to using the light switch).
#Todo: add scoreboard leadership with acronyms/name entries.
At least there is a trophy already 🏆 if you succeed - challenge accepted? :)

As seen in logic analyzer capture of the two available speeds, the fan speed is set by shifting trigger timing for Triac. So basically we can shift the timing inside the interval safely = variable fan speed.

#TBD
#INSERT MQTT addresses table
As ESP8266 only provides WiFi as wireless communication, MQTT is added for a proper way to add the fan to smart homes (e.g. HomeAssistant).

HTU21D sensor breakout board is used because it fits nice physically. Note that internal temperature sensor is for heating element of humidity sensor. So if you poll humidity sensor too much, temp will rise and might even wear out sensor sooner. Bonus: you can use temperature sensor for approx. ambient temperature.
Quick and high raise of Humidity will trigger shower mode with high fan speed till threshold is less than configured.
Do not forget to check hole in rubber for sensor that it is sealed properly (hot glue works nicely).

I have written down and remove this section again, as I do not want to play out my trump open handed when applying with @Maico.
The deleted, crossed out line might be extended to a section later with future projects satisfying USPs.

- Create modular/custom PCB layout (for ESP32-C6?). ✅ Circuit done, not uploaded/shared/public yet. ☐ Create new dokuwiki-section for schematics. ☐ rewrite for Zigbee in ESP-IDF/FreeRTOS. ☐ Let others profit for € or $, sell (to Maico? PCBs on Tindie?).

Deleted section is still to be unlocked, not published yet and has been replaced by this crossed out line as placeholder.
Actually, this hole wiki is not listed on google etc. (yet)

#TODO: remove/hide for application
- Use free GPIOs for either: * ultimate power save: create (n-mosfet?) circuit to reset MCU even from deep sleep with light switch, kept alive if already running. else show cached webpage (on openwrt) * presence sensor / motion detection * use for 1 wire LED (ARGB Neopixel WS281x DIn only) - transparent case for cool strobe disco fan effects? * connect hall sensor for magnetic open door sensor or fan RPM fun / poti on door angle
- build 3D printed external devices: - wireless WC-occupied LED-sign with button for Wi-Fi beacon (DTIM interval) for ESP8266 light sleep wakeup
- connect to wireless button on big button of flushing to turn on fan
- add leadership scoreboard for pee game + @Maico-WC-fans for some motivational fun&fame = brand recognition
- connect with (Zigbee) radar presence sensor to know how long somebody is on the WC or just inside the room
- create app widget for smartphone (well, because, you know..), keep it cloudless!
- diffused LED nightlight (warmwhite/RGB) and use as visual door bell too (inclusion of deaf ppl)
+ PCB decides if light switch actually switches light bulb or LED night light
¿ play tones over fan noise (IMY polyphone style) + party-mic-appmode ¿feasible?
+ Use the fan as acoustic door bell via MQTT - HeartBeat (MQTT?) for security
- MQTT interconnect several fans with “serverless” master/slave
- If I had more GPIOs: add motion/presence detector; add night light; add hall-sensor for fun; add poop smell sensor; add DC-motor interface for air-freshener spray; wired interconnect with smoke sensors ✨😴💭💫🎈🫠🪂
- (as just discovered there is already some new NFC products): NFC service-card to read out serial#, date and run time.
- Why would I want to have M-line too? + have shutter like ECA150 K

Last of my thoughts: 💭💫
- Readers task (you) if wanted: Recreate original PCB layout in KiCad with help of schematics and PCB scans - or help in creating custom PCB.
- Learn from ECA150 VZC and participate in mail-giveaway, win some prices. Why would I want to have (to me still mysterious) “M”-line too? There is some NFC-app series now too?!

What actually causes poop odor? Main contributors:

• Hydrogen sulfide (H₂S) — rotten-egg smell
• Ammonia (NH₃)
• Volatile organic compounds (VOCs) — mercaptans, indoles, etc.

MOS VOC sensors are good for: “Something smells off”, not “It’s poop”, which is fine for this case. Therefore BME688, SGP40 or sensors by Renesas would be my choices to investigate in.

The PCB is optimized for low cost, as you can see on the series resistors for light detection. I like the design, it does not seem over complicated - this is my first AC-fan RE though. What I absolutely dislike is that Triac switches Neutral instead of Live conductor.
The modification project was fun, I got an understanding how this AC fan is driven. LNK was upgraded, only the optocoupler was killed by me only by accident in the beginning and had to be replaced - no other harm done (besides the knife attack on PIC16 traces of course..) :D
The ESP8266 with LNK306 and ASM1117-LDO module, sandwitched with HTU21 is doing its job fine for ~3 years now (time of writing) without any issues (actually 24/7 w/o night power saving).
What would I do differently if it was my product? I would build it more modular with better galvanic isolation from logic level to mains AC and switch Live instead of Neutral with Triac. An MCU with Zigbee would be better suitable for smart homes. Actually, I have build the circuit as schematics already. @Maico: Are you interested? I also have further ideas and USPs ;) I might like to sell parts of the work, also freed of 💩 and kack- labels, replaced by nice Maico design, maybe?. Yes, good choice!

@reader: I hope it was a write-up to enjoy :) Feedback and corrections welcome! Consider to donate some real cookies 🍪 as this page uses none.
Also win free gift 🎁 by helping to solve the Riddle of ECA150 VZC (RC)

You are now pleased with the downloads:

Let me download everything!
#unlock download link later, after application.
#TODO

Software license ?! CC? (L)GPLv3?
I am aware that the code is not pretty. As always, in and out, 20 minute adventure 🤡

#insert OTA binaries
#insert german html translation #TBD
#insert schematics
#insert pdf-article (dated)
#download everything together, zipped (with date tag)
Your task if wanted: Recreate original PCB layout in KiCad with help of schematics and PCB scans
Note:

own, custom circuit with ESP32-C6 already created, but not published/shared yet. #TBD

→ “the timestamp of software isn't from 2022, are you cheating?” I am not, I have corrected some bugs and tried to tidy up a bit for your pleasure just before releasing this write-up. Didn't bother, no cheating, no AI used.

Obviously I could not take apart the fan in the shared flat. But as written in section PCB scan, I have gotten a burned up, rusty fan with water damage on Kleinanzeigen.
So, how to disassemble it?

1. pull off fan rotor to the front (it is tightly stuck onto the shaft, consider winding a string behind all rotor blades and pull on that)
2. pop off rubber sealed lid carefully on the back side (not glued, only stuck 👍 still handle carefully)
3. losen all obvious screws on front and backside of fan
4. take apart with brains - unlike me (motor toast⇒I ripped the case apart and lost a photo due to it.)

It has proper industry bearings. Some photos (-1) for you to enjoy.

I do not own ECA150, I have just stumbled across a nice photo of RC version on Kleinanzeigen (hope I don't violate any copyright?mail me). I have gotten curious about the ICs used on that PCB and am sharing guesses.

The etched “silkscreen” on the PCB says SIM300-0 / TCM300-0 module. According to the logo, a TCM300 868 MHz module by EnOcean is used. Link to pdf datasheet (2MB).
The power input looks different with the two big yellow caps and no L1-line (how does it work?).
The output is: 2x wire socket (J3 marked 1 | K) + 3x wiresocket (J2 marked 1 | M | C). “1” is probably L-mains and “K” = Common / Neutral or “Kapillar”. What is “M”? A Sensor? Or rather „Mitternetz“ Schalterphase / Steuerphase, a second motor input? J2 is probably used for the electrical shutter.
Really disappointing that there is no mention of J2 and J3 wiring or any fan connection (or am I blind?).
Pictures are hard to come by (probably best on Kleinanzeigen/ebay/online market) - I have not checked for long. Question remains: What is on the underside of PCB?
A link to official Maico pdf datasheet (17.3MB, multi lang) here.

🎁 Does anybody have the label of the IC “U1” cycled in red? How does the back side look like and what can be read on the ICs? I give away a free grift to chose from for electronic tinkering (shipping included within Germany): Just submit some good info or (broken) PCB

Send mail to: <#TODO insert mail> - no spam please.

ECA150 ipro is a bigger fan (the number represents the duct diameter), here 150mm. Throughput is 200-250m³/h. There are now four modes (Comfort, Night, Save(?→Spar), Power) - why do I not have such cool names? *note to myself*
Apparently there is ECA100 ipro RC too. I do not know how it looks like. For ECA150 see RC spare replacement PCB (for 318€?!) #Känguru side note: But 318€?! That's 636 DMark! That's 1272 Ostmark. That's at least 6360 Ostmark auf'm Schwarzmarkt! … Jaa, I know what you are now thinking … 6360€ today would be 127200 Ostmark auf'm Schwarzmarkt …
There is a cheaper version without wireless master/slave interconnect https://www.maico-ventilatoren.com/produkte/p/platinen-g59683/pl-eca-150-ipro-vzc-h-b-p132185 (for only 90€ on Maico HP).
What MCU does it use? PIC16 again? Then RC version probably shares the same MCU for motor control on the backside of PCB with added wireless module? I have no idea (yet?).
Maybe we should build things on our own again? Maico fun chapter #2?

There are at least two even more simplistic versions in 150-series. I have not investigated how they might work or what their features are. See pictures cross-loaded from official Maico HP (@Maico: is that ok? *kindly ask*).

[RC | VZC | VZ | ipro K only]

I wonder about the acronym lettered names. The are more simple, single sided PCBs (VZ version for mere 40€..). VZ has a single potentiometer to configure some value/parameter and 3x wire socket only. Question: The missing 'C' in VZ probably stands for “Control”, missing logic. And 'V' and 'Z'? Verzögerungs-Zeitschalter? - I am having a hard time guessing here, is this somewhere public or obvious? And “ECA”? “Einbau Compact Axial”?
I get “H” for humidity, “B” for Bewegung/motion, but why “F” when it is called “Lichtsteuerung” / controlled by light sensor? Double confusing as “H” is “Feuchte-Vollautomatik” and not humidity on the german Maico HP.
So what does ipro K stand for? eleKtrischem Innenverschluss? There is a version with only “K” letter, (no further suffix). It has 2x+3x wire sockets with only a huge cap and a resistor(?) (style coil?) on the front. I admit, would be fun to see how the lasts cents are shaped off of this product.
@Maico: Why does the name scheming sound like my variable names? ¯\_(ツ)_/¯ (this is no rant, just my unfiltered string of thoughts).
I have just googled economic news to Maico and have seen that the new generation has taken over with Mr. Müller & Mr. Beck in 2025 and that an NFC-App enabled version has been released? All the best! :)
*note to myself*: look into NFC-App / PCB
A kindly meant observation: If I look at the Maico HP, I feel not that I have a good guide to chose what I could use as a customer. If it was my product page, I would have a category product selector guide filtered by my special use cases via keyword filter. Then have some nice dynamic comparison overview of relevant products. I also had hard times finding spare part pages without a web search engine. It feels like a riddle to find out what is smart to chose - just my 2 cents. :)

On RC there is no optocoupler on the front side of PCB (is there one one the back side?). It is missing L1-light switch AC-input. How come cheaper versions have L1 light switch input, whereas RC does only have L+N? Is it motion sensor only? WT.. #note: check manual
There are three diodes around switching regulator(?IC label?), 680 µH inductor, the 4.7 400V cap, some minor parts and 4*100Ω next to the two fat caps (I wonder about).
One button, one LED, a pin-header for available sensors. TCM300 with wire antenna on RC version.
There are two large yellow 1.3µF 250VAC caps on the input(? or are they used with motor? Are that the new X-Class caps for EMI?)

The VZC (non-RC) version seems to be more similar to ECA100 ( - apparently there also is a RC(H) version for ECA100). Visually there seems to be an optocoupler and L1-light switch AC-input. It has two buttons, four LEDs and two jumpers.
It shares the two large yellow caps with RC-version though.

How do other fan/ventilator manufacturers do it? How do the PCBs of ebm-papst look like? Like a Bosch.?
Oh, and I have just learned that there is some NFC-app enabled product line by Maico?!