fix faulty non working Maytronics Dolphin M500 pool robot complete diagnosis and repair

in part 2 of my Maytronics Dolphin robot fixing series, I repair a M500 top of that the customer was quoted by his pool shop as needing a complete motor block unit . This shows that with some diagnosis and fault finding skills , you can work out the problem.
The robot is repaired enough to be working again but in an upcoming episode we take the impeller drive motor apart looking for a problem that causes the robot to stop. This is solved by changing the roller bearing inside the main drive motor.

[@TonyTony-by2vr]

One of the best do it yourself, disassembly and reassembly videos I’ve ever seen in my life. Mic drop.

[@Dentinvent]

After that nice comment, I have to watch it again myself. Many thanks . I am planning to make more videos with some other models ( starting from a broken machine to complete diagnosis ).

[@alexvengerovsky2812]

@dentinvent - thank you for the detailed and thorough explanation! Very useful. On my M5 with tracks and rollers removed, the dry test goes well on one side (~10 sec) but on another side the motor stops after 3 sec. Before opening the motor I wanted to ask the expert - thoughts?

[@Dentinvent]

I always thought both sides operate for the same time . I’ve taken many of the motors apart and I’m making videos on current draw and bearing changes. The robot in the video ended up stopping all the time . I took it apart and compared the two sides and one drew more current . I changed the bearing on the high craw motor and … it works like normal . Still working on that video of you want me to make it . I did note high draw current does make the robot stop completely.

[@Dentinvent]

If you open the motor it usually seals back well and you get a chance to check moisture inside it so that’s a bonus .

[@pattiyohe4196]

I have an M500 cleaner. One of the climbing pads broke so we replaced all 4 of them. Now, the cleaner will move left, right, and rotate, but will only go forward about 2 feet. It shuts off after 5 minutes of rotating around. What can I do to fix it? Out of water test appears fine. Could it be the bearings? We are not sure which parts to order. Thank you.

[@Dentinvent]

If it worked when the climbing pads were old and worn, it possibly could be that the new ones are too tight . Are the pads genuine Maytronics ones ? In my video , this cleaner kept stopping afterwards and it was the bearings . I’m still making that video . I’d try swapping the climbing pads ( rings ) back and let me know if that works again.

[@pattiyohe4196]

I was hoping this video would help me fix my M500's bearings. You started out fixing an M500, but during the final out of water test, you are showing an M400.

[@Dentinvent]

That out of water test was actually a M500 set into the body of a M5 Liberty ( has no active brush in the middle of the robot body ). I’ll still make a video on the bearings. Did a heap of tests on current draw with old bearings and new bearings and strangely , seems like the new bearings were drawing MORE current ? Didn’t understand that but the new bearings on a machine which kept stopping would actually fix it. Stay tuned and I’ll make that video soon.

[@justfun-ij5xn]

What controls direction - the board in the motor or the board in the Power Supply? Replaced corroded board in motor housing now it starts impeller and drive motor right up and only goes in one direction - no self test happening????

[@Dentinvent]

The direction is controlled by the board in the motor . The power supply mainly just gives power and timer functions and can send signals to the motor to stay on floor etc. I think your problem is still in your motor box. Did you check the actual drive motors for current draw? I have found the actual current draw can affect start / stop of the robot . If only one of your drive motors is running, it will affect direction.

[@justfun-ij5xn]

@@Dentinvent it is an M4 so only one drive motor. Board must not be proper one as from eBay seller.......ugh.

[@Dentinvent]

@@justfun-ij5xn Best way to get a replacement board is wait for a broken robot to come up that does not work but assess to make sure it has no water into the motor housing (work this out by the seller's description of how the robot died). Don't buy one off ebay as the seller makes ten times the price of a broken robot.

[@mannycancel120]

Mine works in Manual Mode but when i run it in Auto it runs for a few feet and then stops. I did the upside down test and it runs and then stops like its suppose to. What can be the problem?

[@Dentinvent]

Do you have the motor out ? If it runs with motor in the water but still stops, it will most likely be the drive bearing of the motor . Let me know and I’ll guide you .

[@Dentinvent]

Do you have the motor out ? If it runs with motor in the water but still stops, it will most likely be the drive bearing of the motor . Let me know and I’ll guide you .

[@mannycancel120]

@@Dentinvent thank you. Ill check it out tmw. I appreciate it.