An air condition technician brought this board to my shop for repair. He usually comes into my shop and start to explain the problem. He has a high tone of voice and the whole area could hear him talking about that board. Anyways, he is a good guy and he always brings tones of things to fix. Check out the board.

This is the second board I have repaired that comes from the same air condition model. This has a different problem and with that comes different repair techniques. This board was dead.

Plug in power and I could hear a faint click of a relay clicking but nothing happens. The lights on the board come on but flickering and when I checked the board that has all the LED lights, look what I found.

It was dirty and corroded and later on I found out that water came on that board and was not cleaned. I have to clean that board and re solder all the soldering joints. I plugged it in power and all the light come on and steady this time. That is a one step further to fixing this board. Here is the board from the other side.

Now that I am done with this board, my focus shifted to the main board. As I said before, I could hear a relay clicking but nothing is happening. I started checking for water damage on that board and I found something. Look at this

It was a 3.15 fuse and it was intact but I went the extra mile and replaced that fuse. I also cleaned the fuse holder on that board. I am pretty sure that was not the issue with this board because it was doing its job in delivering power.

Look at this dirty fuse holder. It was nasty and corroded. I replaced that holder with a brand new one.

Since I have repaired this kind of air condition boards before, and the main relay was not clicking. The relay needs 24 volts to come on to transfer 220 AC volts to the main pump. I traced that voltage source and it was coming from these two integrated circuits.

As you can see, it is TD62003AF. They were also corroded and needed re soldering.

These  IC’s were giving output of 15 volts each that go directly to the coil pins on that main relay. But for some reason these voltages were not reaching the coil pins. Once I cleaning and re soldered all the pins of both IC’s I could read 30 DC volts total output to the pin of the relay. I clicked with the remote control and guess what, the relay clicked and 220 AC volts came out. Sorry I could not take a photo of that because the board was hanging down from the AC unit in the customer’s house. The Air conditioned came on and it was cool and breezy.

Mission Accomplished.

This article was prepared for you by Waleed Rishmawi, one of our ‘Master Authors’ and currently working in the Bethlehem area of Palestine repairing electrical and electronic equipment.

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Note: You can check his previous repair articles in the link below:

https://www.electronicsrepairfaq.com/no-display-in-mini-lcd-screen-repaired