I have a gate opener system that is powered by a small circuit board, shown in the accompanying photos. The board uses a 12-volt battery backup, and it receives an 18-volt DC current to keep the battery charged. Right now, the board runs exactly as it should when only the battery is connected. The problem is that, for some reason, when I connect the 18-volt power-in from the manufacturer-specified transformer, it blows the thermofuse in the transformer (which cannot be replaced). The first time this happened, I figured it was just a bad transformer. However, the board blew a second transformer, so there is something going on.
While I had the 18v power connected, the green LED in the lower right-hand corner came on, the way it is supposed to, to indicate that the board has external power. Again, everything on the board works just fine when only the battery is connected.
I don’t see anything on the front or back of the board that looks like it could be shorting out the board, resulting in a blown transformer. I would welcome any suggestions about things that I could look at as possible faults. Also, if anyone is interested in trying to repair this for a fee, I would be interested in talking to you.
These boards cost $200 new and can be had for $80 used but I hate to throw it away if there is a simple answer to the problem. Thanks for reading my post.