Dolphin Vacuum Starts Then Stops

[mculik5]

I have a Doheny Dolphin Discovery; I believe it's equivalent to the Maytronics S200. This will be its 6th summer. It worked fine last summer and was stored in my garage over the winter. I built my own power supply for it that has worked flawlessly for a few years and is outputting the required DC voltage, so my issue is not related to the power supply.

Basically, when I turn it on, the unit starts like normal - the blue light starts blinking and the unit moves back/forth and then starts its cleaning cycle. However, VERY shortly into its cleaning cycle, it stops completely and the blue light goes out. Initially, it would stop after about 30 seconds, but each time I restarted it, it would run progressively longer and has now maxed out at about 2 minutes.

During the time it does run, it seems to be working. It's definitely vacuuming and the tracks and sweeper spin. I haven't been able to get it to climb a wall and move sideways yet, so I'm not sure if the deflector is moving, but it does move easily enough by hand, so I know it's not jammed. I also confirmed that the impeller turns easily enough by hand, and again, it is definitely vacuuming.

Anyone have any idea what would cause it to shut off so quickly? Are there any sensors within the unit itself that shut it down if it:

- Overheats
- Jams
- Isn't generating enough suction
- Overload (see power supply note below)
- Over-/under-voltage (see power supply note below; I don't think this is really the issue, but could be a bad sensor)
- Has some sort of "navigation" or position sensing error
- Etc., etc.

Lastly, regarding the power supply, I have it outputting 29.6 volts at the power supply (multimeter verified), which is the same setting I've used since I built the power supply a few years ago. It's a 480 W power supply, and the wi-fi switch I have connected to it, which also monitors watts used, hasn't gone above ~140 W, although the update frequency is only about 15 Hz, so it theoretically could spike an overload that I wouldn't be able to detect. The total DC wire length is longer than just the cord to the unit because I have the power supply remote mounted and run a poolside connection under my patio. Again, the 29.6 volts has worked fine with this setup for a few years, but thinking maybe I had some wire degradation over the winter, I bumped the voltage to 32 volts and got the exact same result - starts then stops.

Also, what's the typical lifespan of these things? Again, if I can get it going, this will be my unit's 6th season. It's in the pool (SWG, vinyl) 24/7 during the season and I set it up to run 2 hours daily. At the end of the season, I clean it thoroughly and store it dry in my garage. I'm in NJ, so our season is about 5 months long, which equates to about 280 hours per season.

Thanks!

 

[JoyfulNoise]

My signature has a link to my thread on my journey with robots. Go to the end where I take apart the motor assembly. It’s very likely your motor case has water in it and/or the drive motor is shot. Also, if it’s sluggish when it moves or turns, it’s very likely the water pump motor is dying. These are cheap, brushed DC motors that will fail after about 5 years of use. You got 6 years, that’s about the life of these things. Don’t bother trying to rebuild the motor assembly, you won’t be able to unless you can scavenge spares off of eBay or some dead unit you find. Maytronics does not sell any of the critical internal components. You have to buy an entir motor assembly for $450 if you want to replace it. At that price you might as well just buy a new robot.

 

[gingrbredman]

One other thing you can check is to see if there is anything stuck inside. I had a Pentair version (Maytronics, Dolphin like) and a stupid little diving gem was stuck in the brushes that prevented it from operating correctly. It would start its diagnostics check when powered up, move a little back and forth, then stop. Took out some screws, and there it was. After 6 years of life, probably not that, but worth opening it up and checking. No need to get into the motor for this check, just a few screws and you should be in.

 

[Jimrahbe]

Mc,

When the robot powers on, it runs some self-tests. It moves forward, backward and the, blows water up through the suction motor. If any of those tests fail, then robot will just turn off. The tests look at the current the drive motor and suction motor use.

There are only two things that you can really do much about. The suction motor can suck up hair and string and it can get wrapped around the suction impeller. I've had this happen a couple of times and removed the debris has fixed the problem for me.

If your robot has a swivel on the power cord, they can get corroded and fail. I have seen people here that have taken them apart and cleaned them, but that is something I have yet to do.

Personally, I look at my robots as consumables, just like I do my saltwater chlorine generators. Other that simple things like the tracks, I would not spend the money to replace any major parts.

Thanks,

Jim R.

 

[mculik5]

Thanks for the feedback. Going to open it up today and see what I can find.

@Jimrahbe - I don't have a swivel cord. I'm familiar with the startup process you described, and my vac is getting passed that (it hasn't stopped before or during the startup yet) and THEN stopping. That's what I find bizarre. No debris on the impeller that I can see, but I haven't taken it apart yet.

Will keep everyone posted. I'm guessing @JoyfulNoise is probably on the money. Preemptively posted this thread to get thoughts on an alternative approach for chapter 2 of my pool maintenance experience - Dolphin Probably Dead - What Next?. Would love your thoughts.

Thanks!

 

[wireform]

Dolphin also has a motor block reset which would mean unscrewing a few screws and
re-seating it carefully. This being done soon after shipment if the box got jostled too much but who's to say it couldn't happen during ownership at some point. I'd give it a shot.

 

[JoyfulNoise]

Dolphin also has a motor block reset which would mean unscrewing a few screws and
re-seating it carefully. This being done soon after shipment if the box got jostled too much but who's to say it couldn't happen during ownership at some point. I'd give it a shot.

Different problem but similar concept is the fact that the plastic bushings on my robot had become warped after 5 seasons and I had to replace them. The non-circular bushing was causing the treads to skip out of the drive wheel gear teeth and this would make it harder for the robot to move. The motor assembly is only held in with two screws and there's very little in the way of positioning or clamping of the motor assembly to keep it lined up so that the drive gear properly engages the wheel. Once you look at it a bit, it's very easy to see how jostling it too much could cause the motor to not be seated properly thus causing the gears to jam up.

I think there's a lot to be desired with their internal designs...

 

[ride525]

I've had two Dolphins. Both exhibited the symptoms you describe. And were similar to symptoms that JoyFulNoise wrote about. Both my motor assemblies leaked and a motor failed. Only solution Maytronics offered was a replacing the whole assembly at a cost of $450. And they were out of stock a year ago. I'll bet if you pop off the top of the motor assembly, there will be a small amount of water in there. Maybe not a lot, but it only took a bit to make the motor fail.

 

[mculik5]

Thanks everyone! Boy do I feel dumb...

Took it apart today and found a piece of plastic on the impeller. I could still turn the impeller by hand, but I removed the plastic and decided to try it again before taking it apart further. Wouldn't you know...it worked...

I am interested to see if there's water in the motor, but I'm going to use it while it's working and mess with it AFTER I get the pool cleaned up.

Interestingly, the wattage meter I have hooked up registered between 94 and 105 watts when it was working today, vs. 120 - 136 yesterday, when it was starting and stopping. I remember it running at ~100+ watts last year, and figured the extra 20 watts or so was from a bearing that rusted over the winter or something like that and not a big deal. However, I'm now thinking the overcurrent protection on the unit is more sensitive than I originally thought. I guess that makes sense if they're using thin wire and thin PCB traces at the max of their rated ampacity because they're cheap but want to give the appearance of quality and don't want to have to replace parts under warranty because hair got tangled on the impeller and the unit was running an extra 2 amps for an extended period of time.

Will see how long she lasts and will check for water in the motor AFTER I get things cleaned up. Thanks for all the help, and thanks for the comments in my other thread, as I now have a plan for when I do need do buy some new stuff.

 

[wireform]

The over current protection is to save the motors.

 

[mculik5]

Boy is this a roller coaster...

I verified on my wattage tracker that it actually ran the full two hours yesterday, which is what I had it programmed for. Cleaned it out this morning, put it back in and....

Now it's failing the startup checks. Moves about 10" in one direction and stops... So, off to the pool store I go this afternoon...

Will take it apart and report back as soon as I can.

 

[mculik5]

@JoyfulNoise - Tagging you because you seem to have knowledge of electric motors and stuff.

Apologies for the delay in posting. Been crazy-busy, but finally had some time to poke at the robot vac. I took the whole thing apart and opened the motor case. It wasn't wet, but there was some water vapor and a surprising amount of gunk and rust considering everything was in such a sealed area. The board and the track motor looked good. I took the pump motor apart, cleaned it and shined up the commutator bars. Brushes had plenty of life left and slid smoothly in their housings. Bearings felt decent.

So, I cleaned and lubed the O-rings and put the whole thing back together.

Good news first - the unit turned on and attempted to clean for a long time, and my power monitor showed ~100W vs. ~130W or so before! So, my guess is all the gunk and stuff was becoming a problem for the pump motor, and cleaning things fixed that, although I have no idea yet whether it will be a long-term fix or not.

Now for the bad - and hyper-confusing - news...

The pump motor appears to be spinning backwards. When I put the robot in the pool, it kept doing wheelies and wouldn't climb the walls, but it kept running at ~100W. Confused, I pulled it up and held onto it while it ran just below the surface. Interestingly, it's SUCKING through the OUTLET ports.

This is hyper-confusing to me because I didn't take the brushes out, and the motor connection on the board is unidirectional, so I'm not sure how I would have reversed the polarity. I did spray the brushes and board that are underneath the motor cap with motor cleaner (https://www.amazon.com/CRC-05018-Lectra-Motive-Electric-Cleaner/dp/B000BXHWCA) and blew everything off. The only thing I can think of is that I assembled it with the motor cap turned 180 degrees. Would that cause reverse running in a permanent magnet, brushed DC motor?

Thanks!

 

[JoyfulNoise]

Did you unscrew any of the wires that connect to the brushes? These are DC motors and so the polarity matters as to which wire is connected to which brush. On my motor, there was a yellow brush of paint on the underside of the rear cap on the side with the red wire. So when I reassembled it, I was sure to put it together so that the red wire and yellow marking matched.

 

[look30]

Oh boy … my 3.5 year old S200 is doing the same thing , starts moving for a few seconds back and forth then stopped . It did the same a month ago when I swapped the main wheels because the one on motor side was obviously used a lot and got some more life out of it but now is back to not cleaning . Looks like only fix is to buy a new one.

 

[JoyfulNoise]

Oh boy … my 3.5 year old S200 is doing the same thing , starts moving for a few seconds back and forth then stopped . It did the same a month ago when I swapped the main wheels because the one on motor side was obviously used a lot and got some more life out of it but now is back to not cleaning . Looks like only fix is to buy a new one.

Sadly, yes. They are not designed to be repairable in any meaningful way. You either replace expensive components or buy new. Buying new almost always makes the most sense. It’s the nature of the beast. 3-1/2 years os the low end of what’s been posted on TFP. 5 years is more typical. You just got a more “lemmoney” one unfortunately. Maybe see if you can find a online sales version like the ones on Amazon and then buy the Extended Warranty with it. Try to get yourself a bit more coverage than the basic 24 month warranty from Maytronics.

 

[look30]

What robot and store you guys recommend? I got this one from Marina Pools and Spa. BTW I’m in San Jose CA area.

 

[mculik5]

@look30 - For what it's worth, as I said in my post above, cleaning the pump motor seemed to do the trick for me. No way to know whether yours is having the same problem, but if you're at all handy, it's really not a bad job. Just a few screws to get the motor unit out, then pop the waterproof housing open, pull the pump motor, clean it, lube the O-rings and reassemble. Working slowly and methodically because I'd never done it before, the whole job took me maybe an hour, give or take. Plus, if it's already broken, you're not going to break it any more.

Regarding the backwards running that I posted about above, my only guess is I put the motor cap back on 180 degrees from where I should have, so if you take your time on that step, unlike me, you probably won't have a problem. Unfortunately, while messing with it a second time to fix that issue, I accidentally bumped the voltage knob on my custom power supply and burned out a component on the board. Picture below... I Googled and posted on an electronics group on Reddit to identify the component, but no luck so far finding a match. All I know is it's a diode of some kind.

Before I decided to mess with my broken robot, I ordered a suction-side vac. I decided to try a suction-side vac because they are simpler and therefore should last longer, and because I bought a Betta solar skimmer and didn't want the floating robot power cord messing up the skimmer (suction-side vac uses a hose that is underwater, connected to my sidewall suction port). But the vac got lost in the mail. While I waited, I had success cleaning the motor and held off re-ordering the suction-side vac. I've been quite impressed with the Betta so far (only had it about a week), and am now thinking my vacuuming needs will be reduced, since the Betta skimmer will get most things before they sink to the bottom. So, I'm now considering an Aiper 1500 cordless vac because it eliminates the floating cord issue, doesn't require any fancy plumbing for convenience like the suction-side vac would have and, because it needs to be removed from the pool to be charged, I'll actually take it out vs. leaving it in the entire season like I did with my Dolphin, so maybe...maybe...it will last longer.

The lousy part about these robots is that they are dead simple from a parts and repairs perspective, with only a handful of "wear parts" (although they wouldn't wear nearly as fast if Maytronics weren't so cheap), yet no real parts are available. Maytronics (and I'm sure all the other players, too) charge you ridiculous money for something that could last a long time with a $50 (and that's giving them a generous margin) motor replacement every five years. Instead, we're all spending $800 every five years (or less) and sending perfectly good parts to the landfill.

Anyway...