m500- partially running- impeller problem

May 24, 2010
200
Dallas, TX
My just-over-3-year-old (aka out of warranty) Dolphin m500 is having some issues.

The lights on the control unit behave like I'd expect them to- just turning it on, or cycling through the three programs, everything looks correct. But the cleaner won't move (that's not exactly true- every few times after an unplug/reset, he'll move a few inches then stop). Even after unplugging and resetting the control unit multiple times. Both filters (the winter/mesh ones, not the pleated filter ones) have been thoroughly cleaned. I brought out the remote, and can get him to drive backwards, forwards, and spin in both directions- but it's on the slower side and he veers when trying to go in a straight line, and now that I'm thinking about it, need to verify, but I think he slides in a downhill direction when he's not on absolutely flat floor). Which brings me to the next point- the impeller isn't turning. Or, if it is, it's not nearly what it usually is because there's absolutely no plume of water above him (I still need to hold him near the surface so I can visually inspect but my bet is it's not spinning at all). I thoroughly checked the impeller housing and there's nothing in the way. It spins by hand the way it always has.

Let's assume all the control electronics are working. I'm assuming there are three motors- one for each track, and the impeller motor. So maybe the impeller motor is shot. Maybe there's a safety mechanism that won't allow it to run if the impeller isn't spinning (which provides traction, especially going up a wall). If the motor itself isn't shot, maybe a connector in the cleaner came apart. I have yet to look up the pin diagram of the line that runs from the control unit to the cleaner, but I can't imagine each motor has it's own line. So I'm getting voltage to the cleaner as I should.

If we assume it is the controller, that's just not sending the correct signal, I need to take it in to be diagnosed. It's probably not a blown cap I can replace (although I'm not voiding a warranty by popping it open to check) :)

After discussing with myself, I'm going to take it in to be diagnosed (I've got a factory-approved reseller close by that I trust).

However, are there any other things I can check before doing that?

Thanks!
 
Remove it from the water, flip it upside down, turn it on and see if it test cycles. It should cycle the pump motor, then cycle both drive motors back and forth the same way, then back and for the opposite way. If it turns on at all you know you are getting power, so more than likely the motor has gone out or the computer board isn't sending power where it should.
 
OK- so I took it out, flipped it flat upside down, on top of my leaf vac base so I could leave my phone underneath to video the evidence. It whined but didn't spin the impeller. Then the left track went one direction and the right track in the opposite direction, but didn't reverse it. So I took off the impeller cover one more time, removed the impeller, completely clean, re-attached the impeller, and then, while in the past it had only spun by hand in the reverse direction, it wouldn't usually (at least since this post started) spin by hand in the direction it should be going (pushing water out). I used a screwdriver to assist and "broke it free" (no sound, just an expression) so that it would spin by hand in both directions. Popped it in the water, turned it on, and voila, runs like a charm. Plumes at the surface when it's 9 feet down in the deep end. Checked the impeller output flow by hand when it was up at the waterline and it was pushing a ton of water. I'll pull it out in the morning to check the upside down test cycle to ensure it's 100%. Wondering if something worked it's way into the motor compartment?

Anyway- thank you for the advice to test cycle it- that's what got me in there one more time!
 
Just for the thread record, it's consistently "locking" after each run- before each run, I twist the impeller a bit in each direction. It runs great, for 1 run, then won't run again until I repeat.

Is it worth opening it up and seeing if there's something sticking to the motor shaft or something I could lubricate? I'm mechanically adept so not worried about not getting it back together correctly (unless someone tells me 10 springs will launch in different directions upon opening!). Assuming it' straightforward and sealing up the box appropriately when putting it back together is probably the biggest concern.
 
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