Low cost repair of Dolphin
by Hans MEKEL
Hello. I am a Dutch electronics engineer, and live in the south of France. I have a Dolphin which worked well during eight years, but when I put it in the water this spring, it did what most of you describe, it stopped after one minute. As I analysed a bit what happened with other Dolphins, it must be a mechanical problem. I took it apart and changed a couple of ballbearings, but still it stopped after one minute. Then I decided to "fool" the microprocessor, by changing the value of the resistors which measure the current in the two motors. Those are the 1 Watt resistors next to the mosfets, the biggest on the PCB. I don't know the numbers of them. They are aproxx. 1 Ohm, and I soldered a 10 Ohms 1/4 Watt resistor parallel to them, to give them the value 0,9 Ohms. Now the microprocessor "sees" a lower current than before. Only 10% less, but that's enough to make it work properly again. During the conception of the PCB, they calculated the measurement to narrow, maybe as a programmed obsolescence. I hope that you can repair your Dolphin, with these very low costs (2 times 1 cent) and only an hour of work. Greetings Hans.