Mysterious IC card electronic lock PM640, malfunction repair of unknown manufacturer

"It suddenly stopped working this morning, so I'd like to check it."

It was an electronic lock (IC card lock) that I had never seen.There is no engraved mark and no instruction manual. (Is it made in Korea?) I couldn't search on the Web.

In normal operation, press the button and hold the card key near the switch to move the motor and unlock it.

The big wheel on the front just spins, and there is a slit like KEDEN (KEIDEN) to insert something like a card, but it is not an electronic card key you have.That is, it is not normally used.

Even if the battery is replaced, the operation will be slow and there will be intermittent noise.It was thought that the battery box and cable had poor contact, but when I disassembled it, I found water!It's dripping.

It is a few cc of water.It was water, not the water of condensation.The submerged base is corroded.Part of the diode and resistance is white corrosion and red rust on the metal part.

I removed the board, wiped it as much as possible, cleaned the corroded part, and the operation was restored.

However, the root cause is to replace the corroded base, but when it comes to this point, the main body will be replaced.However, since it is a mysterious electronic lock, it cannot be obtained by us.

This time, it was the first electronic lock, and I was surprised at the cause, but I learned.

However, since there is no emergency power supply terminal, it is a little difficult to physically unlock it.That's pretty much it, so let's do our homework.

I found out later that the model number seems to be "PM640".