Intermittent ON/OFF Push Button Fault, Push Button Repair, Mini Square Chinese Flashlight

High power LED Mini flashlight, that stopped working after accidentally ending up in the washing machine. Stopped illuminating. Dried out, but did not respond properly to the ON / OFF button.

The flashlight does not have screws, so for disassembly requires prying on the sides with a cutter or knife .

The case is put together with glue, so it has to be forced to separate, by breaking the plastic inside a little, since it was heat-sealed at the factory.

View of the very simple internal composition; separated into 3 parts, rechargeable battery, PCB board with mini USB socket and push button, LED board.

After performing various tests, a fault was seen in the button, a jumper on the 2 terminals of the button makes the LED board light up correctly: the problem is located in the 2 internal contacts of the button.

I tried without success, just to rule out that possibility, re-soldering the 2 connections of the button, but there was no improvement.

Therefore, the 2nd repair option, (since I don't have a suitable replacement button) is to apply "ELECTRONIC CLEANER" contact cleaner copiously while simultaneously sliding the button from one side to the other to try to clean the interior contact.

Subsequently, canned air was applied (Air canister on the right for cleaning keyboards) by means of which the inside of the button and the PCB were dried.

Once the PCB and the switch were dry, it was repeatedly tested, responding perfectly, so the flashlight was reassembled.

BE CAREFUL WITH THE BATTERY the truth is, it gave me a scare, during assembly; it became very hot in a few seconds because one of its terminals was short-circuited with the aluminum sheet of the LED, so to protect the terminals I chose to place protective insulating tape (Orange) covering the 2 terminals.

In order not to apply force in the re-assembly. A piece of black rubber was cut from the LED plate. (blue arrow)

Since the two halves were fused together, during assembly and we forced it open; we must make sure that the lid is correctly positioned and apply a little silicone onto the lid before assembling it, so that it dries properly and remains perfectly closed.

END of the Guide.