Pentair prowler 920 / Dolphin /Matronics troubleshooting help

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R

rhosch

Well-known member
May 20, 2018
49
Jackson, MS
Pool Size
31000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Been searching internet and TFP.

2.5 years on robot, it spends most life underwater. Impellar seems to spin free and it churns water above on startup so I think that's good.

The robot will move a foot or two, stop for ~10 seconds, move another foot or two, stop. After a few cycles of that it shuts down.

Out of pool on back it runs continuously at slow speed for a minute or two then stops.

Is this typical drive motor failure I read so much about here? I'm not afraid to replace brushes, but I wasn't sure ify symptoms were pointing that direction or somewhere else since I couldn't find that particular problem description. Probably just bad at searching.

If it matters, I have a new controll box / power supply, and both old and new ones act the same so I assume problem is in the bot.
 
Drive motor most likely. Open up the motor assembly and inspect for water incursion. You can try to rebuild the drive motor but there’s a fair bit of disassembly involved. If you have the right tools you can do it. Might buy you another season or so.

While you’re at it, you should disassemble the impeller motor and clean that up as well. If the bearings are still good you’ll want to clean out all the carbon dust and repack the bearing with grease.
 
r,

When the robot first starts up, it runs a self test That is when it moves a couple feet, one way and then the other and when it blows water out the top. If it fails its self tests, it just shuts down.

Sound like a drive motor failure to me.. We have certainly seen a number of these fail recently. :(

That said, I'd want to check to make sure there is nothing wrapped around the suction impeller shaft. It can still work, yet fail the self test for needing excessive current. You have to actually take impeller off.

Thanks,

Jim R.
 
OK guys, I opened up motor box, pump and drive motors. No water intrusion. Everything surprisingly clean.

Took the back plate off drive motors, brushes are not completely warn down. Look pretty decent to my eye. Some carbon dust present, which I cleaned out well with compressed air and vacuum, and reassembled.

Pump impeller did not have much on it, just a little hair that wasn't impeding motion. I can spin the impellar by finger somewhat easily. There is resistance, but it feels more like magnet than anything, has definitive notched feeling positions that resist at each stop and turn more easily in between. Took off back plate. The back bearing spins freely and smoothly. Brushes look only modestly worm to me. Cleaned out carbon dust and reassembled.

Put everything back together, same problem.

It never tries to move backwards... only forward, both in the water and when dry on upside down self test. I can hear the impellar spin at times in the dry self test, and when in 4ft water it churns the water at the surface pretty good at times while it's trying to decide if it will go or not.

Any suggestion? With the lack of backwards movement, I still wonder if this is a drive motor issue? Has anyone had the control board itself fail?
 

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Did you inspect the printed circuit board in the motor assembly? That is the brains of the unit. The power supply is just a power supply, nothing special. The PCB inside the motor assembly is where all the action is.

Take a look at with a magnifier. Look for swollen capacitors, scorched PCB, or burned traces. Inspect around the power FETs as those are what the motors get their power from.
 
Yeah that's what I was referring to by control board. I did not see any evidence of component failure but didn't look with a magnifying glass either. I was wondering if that is a known failure mode or not. I've read a lot about motor failures.
 
r,

When the robot starts up it goes through a self test. When it is moving back and forth, it is measuring the amount of current it takes to turn the motors. If it sees too much current it will shut off. So, even through the motors appear to work, if it does not pass the self test, it will not run,

Thanks,

Jim R.
 
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So... drive motor still most likely? Brushes don't look bad to me. Anyone think it's worth replacing them anyway, or have any other idea short of the whole $450 assembly?
 
Actually, in that second picture, the carbon brushes are completely worn down. Ona new motor, the copper wire in the block is all the way to the back of the carriage holder. So my guess is that you are getting intermittent contact.

I would replace the carbon brushes. They are cheap. You can get a bag full of them for like $10 on Amazon. Just measure the dimensions and order the closest size. You’ll have to use sand paper to shape them if you can’t find an exact match.
 

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Oh, awesome, I'll give that a shot. Cheap so no harm done if it doesn't help. I guess I thought since the current brushes have to spring back a couple of mm for the motor to fit between they were still good.

Here's hoping for a cheap win.
 
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Well, big bummer. Replaced the impellar motor brushes, pretty easy job. But no dice.

Behavior both on back and in water is identical as before. To eliminate any other variable I removed extension cord I was using and plugged directly to outlet. Same.

The one thing I'm seeing that seems consistent and wrong is that it never attempts to move backwards. Not on back, not in water. On back it just runs continuously forward, ramping speed up and down. In water it moves a few feet forward, stops. Almost like it shuts off (light stops flashing for several seconds). Back in and repeats a few cycles of that.

Drive motor brushes seemed to make good contact and that doesn't really explain why it won't move backwards. Maybe failure of PCB in the motor assembly?

Well, unless someone has another great insight, this is looking like it will turn out to be a much more expensive repair or replacement.
 
rhosch said:
Well, big bummer. Replaced the impellar motor brushes, pretty easy job. But no dice.

Behavior both on back and in water is identical as before. To eliminate any other variable I removed extension cord I was using and plugged directly to outlet. Same.

The one thing I'm seeing that seems consistent and wrong is that it never attempts to move backwards. Not on back, not in water. On back it just runs continuously forward, ramping speed up and down. In water it moves a few feet forward, stops. Almost like it shuts off (light stops flashing for several seconds). Back in and repeats a few cycles of that.

Drive motor brushes seemed to make good contact and that doesn't really explain why it won't move backwards. Maybe failure of PCB in the motor assembly?

Well, unless someone has another great insight, this is looking like it will turn out to be a much more expensive repair or replacement.
Click to expand...

Could be a failure in the PCB.

Only other failure would be to take apart the transmission that sits on the drive motor and look to see if the gears in there are damaged. Hard to believe it would go forward but not backwards in that case.

You really can’t repair the motor assemblies on your own. Even a pro is probably going to have to charge you a significant amount of money to get it working. Probably best to scrap it and put those funds into a new robot.

Outside of the warranty period, it’s not financially sensible to fix them.
 
Yeah, and I'm not seeing a replacement motor assembly (part 360365 for this model I think) for under $600.

I hate that but spare parts looks like where this one is headed.
 
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rhosch said:
Yeah, and I'm not seeing a replacement motor assembly (part 360365 for this model I think) for under $600.

I hate that but spare parts looks like where this one is headed.
Click to expand...

I’m out of the robot game after I spent a good month trying to resurrect my old S300i. In the end, it wasn’t worth it and, long term, I went back to using a suction side cleaner. Works fine in my pool and I can rebuild it as-needed for a lot less cost. I no longer recommend robots to folks that ask, they are expensive toys designed to suck money from your wallet and, when working, leaves from your pool …
 
Hmm... well I see the 9995388-EX assembly says it's for the prowler 920. They both look the same visually but this one is just $450. Being half the price of replacing the whole thing (and since the control box is already brand new) I guess that makes more sense.
 
I've thought about suction side cleaner but the way our pool is plumbed and setup that isn't ideal. We have an infinity edge and smaller catch pool. The skimmers on upper pool don't really do anything since the flow is all away from them and over the infinity edge. There is a single skimmer on lower pool but because of the requirements for varying water line and height of the walls there, that basket is like 3 feet below the coping and a real pain to reach into and take the basket out. So it's set up to pull 100% from the 4 floor drains in the lower catch pool. The infinity edge functions as a giant skimmer, collecting everything in catch pool.

All that to say... we have no real ability to use suction side cleaners. I have an unused plugged port that I could plb for separate pressure side pump but then just easier to use robot I think.

No great solution.
 
I'll suggest a different direction than everyone else.... Take apart the moving parts. The wheels and cleaning brushes. Look at the bearing surfaces. Mine had completly roughed up all of the bearing surfaces over the last two years of service to the point that it could not move much at all. A replacement motor under warranty did not help much. Only after last season did I really dig in to find this. I have had all of the wheels and brushes on order and just received most, except for the wheel kits are on backorder. The best part is that all of these parts add up to only $140
 
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