by Steve Hobrecht
(Los Altos, CA)
I have rev 3 electronics in my seldom used but now broken Dolphin Diagnostic. The electronics have been modified by Maytronics over the years, I assume because of cost and reliability issues. They went from using DMOS motor switches to a NSM LMD18200 (I was part of a design team that designed these early IC power controllers) and I do not know what they are using now. Unfortunately, they are or were using a supply voltage that is too high for most common inexpensive drive electronics solutions. If they kept their power supply to a more normal 24-28V instead of 32-37V, they would have had more options on the electronic design.
There is a very common problem being experienced through the use of underrated power resistors used for the current sensing of the drive motors in addition to water leakage into the motor control box.
I was initially very impressed with the Dolphin performance but now am beginning to see the cracks in the overall design work being put into the units. The designs look to be done by a microcontroller expert without the expertise of an Analog/Power management design engineer.
I have been working in that field for over 20 years and would love to help them with their motor drive electronics.
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