Friday, 2 April 2021

Energenie MIHO109 - Converting to Tasmota

 


The MIHO109 smart plug is different from most Energenie devices because it communicates directly with their cloud service via WiFi. Although the Energenie service has an API, I wanted to see if I could integrate these plugs directly with Home Assistant. I took one apart to take a look...

I found they come apart easily as there's no glue or clips to pry apart, just 3 T8 safety screws. Inside there's an ESP8285 on a separate module (essentially an ESP8266 but with the flash memory included). I traced the pads to the various pins on the ESP chip and luckily the RX/TX pins are exposed the edge connector.


By temporarily soldering some jumper wires to the RX/TX/3.3v/GND pins it's not necessary to remove the module to flash new firmware. I use a FT232 USB to TTL adapter for this as it also supplies 3.3v to the ESP chip (higher voltages can kill it). I use Tasmotizer as the flashing tool as it has a Windows GUI interface.

 


Once the new firmware has been flashed and the plug reassembled, setup is just like any other Tasmota device.

Template:

{"NAME":"MIHO109","GPIO":[32,1,1,1,1,1,288,224,1,1,1,1,1,1],"FLAG":0,"BASE":18}

⚠ Safety warning
These plugs operate at mains voltage and there are exposed terminals inside. If are are unsure of the necessary safety precautions then do not attempt this. Never attempt to flash the ESP chip when it's connected to the mains.

Samsung 27" LCD TV BN44-00506A power supply repair

This 27" LCD TV is around 10 years old and suddenly stopped working with a pop. Given it's age there was nothing to lose by seeing if it could be fixed. With the power supply out it was clear the fuse had blown along with the blue ceramic capacitor next to it.

Fuses usually blow for a reason so I inspected the rest of the board for shorted or damaged components.

I found the main bridge rectifier D2SB60 was shorted along with the regulator IC STRW6053S.


The faulty components were common parts and easily sourced online. Testing with a load lamp showed the short circuit had been cleared by the new parts and the 5v standby voltage was now present. When the power supply was put back in the TV everything worked OK.

  Safety warning - These power supplies operate at mains voltage and some components may retain a high voltage even with the power disconnected.



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