Nexa remote socket teardown

I have been fiddling with remote sockets for a couple of years now, especially Nexa branded ones. Yesterday, for the first time, I believe the relay has broken in one of the oldest ones -> Teardown time!

There are some kind of screws that I have never seen before holding the thing together. I tried to heat a pen to make a plastic “quick fix” screwdriver, but the screws were too tight and the “quick fix” screwdriver was not capable of delivering the required torque.
Nexa_back01

I used a utility knife, heated glowing hot with a blowtorch, to cut the enclosure. The result wasn’t pretty but it got the job done.
Nexa_front_opened01

Inside immediately visible relay and three caps: a yellow .22uF 275V, 100uF 50V electrolytic, 10uF 50v electrolytic. Down to the right looks like antenna.

2014-12-20 01.01.14

Under the plastic cap there is what looks very much like a bridge rectifier and a transformerless power supply. There are 2 zeners (ZD201 & ZD202), interesting…

The other side of the board has to house the logic and 433.92 MHz RX.

nexa_board_back_01

One of the chips seems to have no visible text, while the other one is clearly a serial EEPROM HT24LC02.

This does look quite interesting, will have to do some more poking another day 🙂

Update:
The relay is 24V, this has also been suggested as a good option for powering a relay an uC from a transformerless power supply that cannot provide much current (DESIGNER
CIRCUITS, LLC – DesignNote 001a)

2 thoughts on “Nexa remote socket teardown

  1. Hey!
    Did you manage to change the broken relay? I am also having the same issue, that the relay is not making any sound but the receiver seems to understand the remote.

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