Maytronics refurbing and reselling to new/old owners

by Steve Hobrecht
(Los Altos, CA)

I have a seldom used but older Maytronics Dolphin Diagnostic cleaner. I have had the unit since 2006 (rev 03 PCB) but only used it occasionally such that it probably has 50-100 cycles of operation. The unit now only runs for the first few minutes and then shuts off.
I have been investigating this unit on the internet and have found out that my problems are very common and much to the disappointment of existing owners, Maytronics is not coming up to the bar to address these issues. I took the motor unit out and found that only half of the positions for screws securing the case had been used and looking at the motor cover, these screw positions had never been used and that the plastic motor cover hole positions were still intact, filled with the grey cover plastic.
Removing the motor cover, I found that the paper dessicant packet was moistened with water and had broken open spilling it's caustic contents throughout the case. The circuit board was still intact and clean. After cleaning up the PC board and case, I reassembled the unit and put it back in the water. It worked for about 45 minutes and then stopped. Since then, the unit has gne further downhill, to the commonly witnessed problem of working for just a short, less than 2 minute period.

Being a retired Electrical Engineer (35 years) in the Analog Design field, I had to dig deeper only to find that the Atmel Microcontroller used does an initial check when first turned on of each of the motors by measuring the current drawn through sensing resistors, R14 and R43. These resistors themselves are under designed for the approximate 1 Watt they need to dissipate during normal operation. If the microcontroller decides during the initiation phase that there is a problem, it can turn on a Siliconix dual DMOS fet, M3, pulling a large current through R31 from the external power supply that has it's own failsafe overcurrent latchoff. The external power supply will hold this state while AC powered and even after because of stored charge in it's included storage capacitors. This is why even after you turn off the unit under latchoff conditions, that you have to wait a couple of minutes before restoring power for the system to reset itself.

Maytronics has been NO HELP! They are now refurbishing these units (with updated and hopefully more reliable electronics) and reselling them in some cases, like me, for only around $450-$800!!!!!

I emailed Maytronics and asked if I could do the repair but was told NOOOOOO!!! I have to send it to a repair center that will replace the motor unit for $$$$$$.

Why can't Maytronics come up to the bar and replace their early faulty electronic designs for a nominal charge or at least provide updated electronics for a nominal charge to those of us who can repair the unit ourselves.

One more thing. The plastic motor housing can start to have stress cracks in the housing around the track motor and begin to leak water. This can been repaired for a short time I suppose with GE 50 year silicone sealer on the side of the case.