Repairing zodiac cx20 pool robot

Thread Starter

smallsam

Joined May 4, 2020
4
I have a zodiac cx20 pool robot, which has started malfunctioning. By my knowledge of it's algorithm, effectively one of the 2 motors in the unit, the drive motor which drives it forward and backwards on its tracks now only appears to operate driving forwards. Notably it also appears to drive forwards when I would expect it to reverse direction.

Any advice on where to start looking? I only have access to a soldering station and basic multimeter.
The motor output going to the drive motor is bottom right of the board, viewed from the IC top side.

IMG_20200504_141258158.jpgIMG_20200504_142429354_HDR.jpgIMG_20200504_142216628_HDR.jpg
 

Thread Starter

smallsam

Joined May 4, 2020
4
Here are some clearer photos of the board. I did pay some attention to the FETs and the electrolytics when I dismantled it earlier but didn't see any obvious bulging or burnt parts. That said I've had very little experience of seeing failures in real life so could easily have missed something.

IMG_20200504_142216628_HDR.jpgIMG_20200504_141411287.jpgIMG_20200504_141333731.jpg
 

Thread Starter

smallsam

Joined May 4, 2020
4
Hi Duke,
Not yet, I'm suspicious of a few things but haven't had time to get it onto the bench and work on it. I'll update the thread if I find anything.
 

dukejensen

Joined Jul 8, 2020
2
I've check the FET's and the transistors the drive the FET's and they seem ok. What are your suspicions? As I have it on the bench at work, but not sure what else to check.
 

Thread Starter

smallsam

Joined May 4, 2020
4
That's where I was going to go first. As the behaviour is that the motor drives all the times I expect it to but only fails to change direction, my belief is that assuming it's an H-bridge or similar setup that there's a failure in there somewhere.

My hope is that the microcontroller is still providing the output to switch the direction but the power stage (motor driver) isn't responding. Rather than invest lots of time trying to reverse engineer the board or attempt to get it into some sort of test rig, my first though was to order the $15-20 of parts to replace the electrolytics and FETs and blindly give it a try.
However if you've gone through the FETs and transisitors that might be a waste of time.

I'd be keen to power it up on the bench to see if you can get it to drive the motor and somehow work out how to force the direction switch (maybe through tilting the board), I assume there's a tilt sensor on there somewhere.

Worst case scenario would be that the firmware is corrupt and it's simply no longer doing the right thing. To prove this point (because fixing that is way outside of my ability), would be to locate the logic level direction coming from the microcontroller and see if it changes direction. The pre-req for proving this out I think is to somehow rig it up and power it on the bench.
 

gingerbeer

Joined Jan 19, 2022
1
Gents. Same problem here (only one direction then blinking red light) - did anyone get any further?

I also tried switching around the plugs so the drive motor runs off the impeller source and vice versa - again it runs for a while but instead of two pulses of the light (drive) the controller gives three pulses (impeller). Makes me wonder if it is something with the motor rather than the circuit board?

(for the search eninges etc: the zodiac cx20 (as sold in Australia) is the same as the Polaris p825 sold in the US
 

Edward0

Joined Jan 29, 2022
1
Hi all,
also having the same problems.
I’ve checked the voltage from supply to the motor pcb and seems fine.
I’ve also checked the resistance on the motors and seem fine around 2.5ohms.
swapping the motor connectors shows the drive motor is working, therefore and issue getting power to drive motor connector.
Issue does seem temperamental as it did work this morning then stopped again.
Any ideas what to check next?
 

Baste903

Joined Dec 9, 2022
2
Hi All,
Don't know if anyone has more information or circuit diagrams for the zodiac cx20. Mine has a problem where the power randomly turns off with no error signals. Sometimes it runs fine for 20 minutes or so and other times only a few seconds. Even without the robot connected, the 28VDC from the power supply will just suddenly sink away to zero.
Any ideas or documentation which might help would be greatly appreciated.
Thanks, Ted
 

Baste903

Joined Dec 9, 2022
2
Hello All. I have the same symptoms as Baste903. Watching with interest.

Cheers Fletchafloat
Hi. I gave up on trying to sort out the power supply and ended up buying a new control box. My concern had been that the robot had actually overloaded the power supply causing it to fail and the same thing might happen to a new control box. I ended up testing the robot by using a couple of 12V car batteries connected in series, each with a battery charger connected. This gave me a voltage of 27V which was close enough to the nominal 28VDC that the robot needs. After running it successfully for close to 2 hours, I was then prepared to spend the money on a new control box and its now working fine. Would still like to see diagrams for the power supply so that I can fix it, though. Best of luck with your problem and happy new year, Ted
 
Hi. I gave up on trying to sort out the power supply and ended up buying a new control box. My concern had been that the robot had actually overloaded the power supply causing it to fail and the same thing might happen to a new control box. I ended up testing the robot by using a couple of 12V car batteries connected in series, each with a battery charger connected. This gave me a voltage of 27V which was close enough to the nominal 28VDC that the robot needs. After running it successfully for close to 2 hours, I was then prepared to spend the money on a new control box and its now working fine. Would still like to see diagrams for the power supply so that I can fix it, though. Best of luck with your problem and happy new year, Ted
 
I have a zodiac cx20 pool robot, which has started malfunctioning. By my knowledge of it's algorithm, effectively one of the 2 motors in the unit, the drive motor which drives it forward and backwards on its tracks now only appears to operate driving forwards. Notably it also appears to drive forwards when I would expect it to reverse direction.

Any advice on where to start looking? I only have access to a soldering station and basic multimeter.
The motor output going to the drive motor is bottom right of the board, viewed from the IC top side.

View attachment 206280View attachment 206281View attachment 206283
Hi , did you eventually resolve your problem? I have the same situation.
 

TerryCMW

Joined Sep 26, 2023
1
Hello everyone trying to repair a Zodiac CX20. I have been searching for clues as to the cause or causes of a similar problem to the one posted by Bacon Sandwich and it seems he is not alone.I have nearly exhausted all of my avenues and was thinking of sending my Motor PCB to a repairerthis week in the absense of replacement parts from Zodiac,and be stuffed if I will be held to ransom by having to buy a complete Motor Box for the sake of a pissey PCB board.Then out of the shadows I came upon this forum and thought "This might be a new avenue " andthen "WHERE ARE YOU Bacon Sandwich ...Dont keep us all in suspense ...Did you find a cure....Its been months ,or,have I missed something here. I and am certain many others would love to know how it all worked out or are you still working on it .I will keep watching ..Good Luck .
 
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