Author Topic: Pool controller  (Read 1730 times)

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Offline rthorntn

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Pool controller
« on: April 05, 2018, 12:18:18 am »
Hi,

I'm trying to work out if this issue is feasible.

A four year old pool controller starts acting weird, it has a pH sensor and a peristaltic pump for acid delivery, the pH readings are erratic, I think today I finally figured it out, the pH climbs past the set point (7.5) then the pump motor starts up to deliver acid, the motor (maybe because it has aged) is putting out interference which is messing with the pH readings, so the pH reads 7.6, I see the pump move for a few seconds and all of a sudden the pH is 5.8 which is stopping the pump?

Thanks for looking.

Richard
 

Offline 0xfede

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Re: Pool controller
« Reply #1 on: April 05, 2018, 06:00:12 am »
Hello rthorntn,

the pool controller is 4 years old but how old is the pH sensor? Generally the lifespan of a pH sensor is 1 year or 2 at best.

Are you using pH buffer solution to obtain a known pH read? After being opened a bottle of buffer will start to degrade in 6 months and is no more accurate after an year.

Hope that this help you.

Best,
0xfede

EDIT: while researching a bit more on the topic I found this nice PDF concerning the pH sensor life and calibration. It is of course marketing material but still contains lot of useful information.
« Last Edit: April 05, 2018, 06:17:17 am by 0xfede »
Semel in anno licet insanire.
 
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Offline rthorntn

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Re: Pool controller
« Reply #2 on: April 05, 2018, 08:16:52 am »
Thanks.

The pH sensor is brand new as is the calibration fluid.

I have narrowed this down over months.

I use Taylor test chemicals.

It's pretty much an issue with motor switching on affecting the pH measurements.
 

Offline 0xfede

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Re: Pool controller
« Reply #3 on: April 05, 2018, 09:25:30 am »
Thanks.

The pH sensor is brand new as is the calibration fluid.

I have narrowed this down over months.

I use Taylor test chemicals.

It's pretty much an issue with motor switching on affecting the pH measurements.

My controller after 10 years or so had almost all caps dried out and a bit of corrosion on it. I replaced the caps and cleaned it with IPA and it started working again. In my case the fault code was 'probe error'.

Maybe this can help?

Best,
0xfede
Semel in anno licet insanire.
 
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Offline wasyoungonce

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Re: Pool controller
« Reply #4 on: April 05, 2018, 10:29:13 am »
Richard...does your pool controller name start with a "Z" and and with a "C"...Zodiac?

If so then your only best option is to change the PH bulb for a better quality one.  The OEM drift too much.  Why...cheap!  These probes cost quite a bit they ent cheap. 

Also PH calibration even for a Lab is quite a procedure with expensive equipment.  Here you are doing it at home with cheap equipment and large environment variables.  I actually gave up on my Zodiac pertalistic pump it was a cluster of a system and having the acid too close to the controller corrodes everything.

I add acid by a hundred or so mil every week and use test strips.

Would love to hear what controller you have.  Have been in contact with some others in repairing Zodiac units.
Brendan
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Offline SMdude

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Re: Pool controller
« Reply #5 on: April 05, 2018, 12:39:58 pm »
I would measure the voltage going to the probe with and without the pump running.
Also check that all connections are good, no voltage drops, and check that ground is not floating.
Can you power the pump from a different source and just trigger a relay with the controller?

Can you post pictures of the setup/ board?
 
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Offline rthorntn

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Re: Pool controller
« Reply #6 on: April 05, 2018, 10:38:39 pm »
HI All,

Thanks all.

FYI I'm just a hobbyist, a perpetual beginner with no formal training.

The probe connects to the controller with a BNC cable, what's going to be the best way to measure that, with a multimeter, any idea what I'm looking to see in terms of normal voltage?

Where would I look for voltage drops?

Floating ground, the pH measuring and acid delivery system worked well for years and I don't think anything has changed power wise?

The acid motor/pump is internal to the controller.

Correct, its a Zodiac Tri, I love(d) it for years, it doesn't have the Chlorine measuring capability.  You can get replacement motors for them online.

Thanks again.

Richard

 

Offline wasyoungonce

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Re: Pool controller
« Reply #7 on: April 05, 2018, 11:38:59 pm »
Richard

the Zodiac tri uses a peristaltic pump to pump acid to the pool and measures pool acidity with PH probe.  Problem is dispensing acid and measuring it.  The pump flex tube gets squashed (it parks the tube flex rollers on the tube) and it dispenses less and less till it gives "PH" errors.  Then you really need to calibrate the probe often. 

Then you need to have the acid container close to pump and acid fumes corrode everything...and I mean everything.  I barley managed to resurrect my controller PCB from said corrosion.  I had transistors corroded legs  :-//...some sort of electrolysis gone mad (the PSU stby pwr causing fume attraction).

Oh also the PH probe coax and BNC...often get very loose I've seen the centre pin of the BNC corroded and disconnected or poor connection to the controller.  Inside the controller the BNC connects by pigtail to a sub PCB (part of the Tri add on) and this connects via main PCB with IDC type cables.  These IDC get corroded out from fumes as well...this I know :--

Anyway to cut to the chase I and many others have given up on acid dispensing and do it manually now.  Its was to complicated for the controller to do this with cheapest parts available the manufacturer used.   I had PH errors pretty much from the start...as others did.  Zodiac tri is notorious for this issue.

Usually your acid pump fail is not the pump just the squeeze tube or pump head.  The pump head  plastic degrades & it breaks.  By now you would also have seen backup battery fails and replaced this?

I've been discussing the Zodiac system with a few others for some time on the whirlpool forum, thread with quite a few repairs:
https://forums.whirlpool.net.au/forum-replies.cfm?t=1389867&p=-1&#bottom

Worth a laff of a read.  If you need more info happy to assist, I'll not be giving up on mine because I'm way too stubborn! |O
Brendan

« Last Edit: April 06, 2018, 12:03:47 am by wasyoungonce »
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Offline rthorntn

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Re: Pool controller
« Reply #8 on: April 06, 2018, 12:35:24 am »
Thanks, I posted to the whirlpool thread.
 

Offline wasyoungonce

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Re: Pool controller
« Reply #9 on: April 06, 2018, 03:02:23 am »
Oi...sorry didn't want to chase you away to another forum..sorry If I cam across that way :-//...your good to discuss here!  The link was to show background info over the years.

Brendan
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Offline rthorntn

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Re: Pool controller
« Reply #10 on: April 06, 2018, 03:04:19 am »
All good, I'm just putting it out there, seems to be a few TRi hackers on there :)
 

Offline rthorntn

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Re: Pool controller
« Reply #11 on: April 07, 2018, 01:45:18 am »
pH just goes round in a loop (7.4, 7.5, 7.6 [motor starts], 5.8, 5.9...) and acid is not delivered. So the peristaltic pump motor or circuitry connected with it is messing up the pH readings, anyone got any ideas?
« Last Edit: April 07, 2018, 01:47:04 am by rthorntn »
 

Offline wasyoungonce

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Re: Pool controller
« Reply #12 on: April 07, 2018, 10:51:24 am »
Ph probes work by producing a small DC voltage that represents ions in the water or PH.  This is a very low voltage output this is why they use coax & BNC.  You couldn't measure it at the probe as a meter
s internal resistance would probably throw readings out.

Although you may be able to do so and look for changes.

Best bet is to take apart the PH unit and look to set up a measurement on the output of an OP amp that represents PH probe output.   I'll go back look at my images I took of my PH unit but what you are experiencing is exactly the same  sort of fail all others have seen.  On spec i'd replace the probe but without looking at the PCB for corrosion or inspecting the squeeze tube that would be futile atm.

How is the squeeze tube?  Is it delivering acid..can you see it pump acid ...you will see bubbles flowing thru the tube?

Have you cleaned the probe and changed cal fluid and cal'd it?

From what your saying your PH measuring circuitry is playing up all over the place.  I saw the same on mine could not determine it and gave up went to manual dose.  Look for corrosion on the connectors PCB and IDC flex etc.
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Offline drussell

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Re: Pool controller
« Reply #13 on: April 07, 2018, 07:18:24 pm »
...
On spec i'd replace the probe but without looking at the PCB for corrosion or inspecting the squeeze tube that would be futile atm.
...
Have you cleaned the probe and changed cal fluid and cal'd it?

He already stated that it was a new probe and reference fluid for calibration:

The pH sensor is brand new as is the calibration fluid.

... and says that he's quite certain that the issue is with the motor switching on affecting the pH measurements.

I would check to be certain that the power rails are nice and clean and stiff if this seems to be the case.  Watching the power on a scope when the motor cycles could be instructive and informative.
 
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Offline wasyoungonce

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Re: Pool controller
« Reply #14 on: April 08, 2018, 12:45:37 am »
... and says that he's quite certain that the issue is with the motor switching on affecting the pH measurements.

I would check to be certain that the power rails are nice and clean and stiff if this seems to be the case.  Watching the power on a scope when the motor cycles could be instructive and informative.

Good onya mate only pointing out a progression of event I'd do when checking.  Also he hasn't replied with information about the pump actually dispensing acid or corrosion.  He also hasn't told us if acid container is actually decreasing in liquid.

 
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Offline rthorntn

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Re: Pool controller
« Reply #15 on: April 08, 2018, 01:06:43 am »
Thanks.

I replaced the pump section of acid tube (it was knackered) a month or so ago.

If I use the test acid function it all works.

In general the acid bottle does not seem to be depleting.

The controller is attached to a wall in a very tight and dark space so I haven't figured out how to check for corrosion.

Also scope was mentioned, are we talking oscilloscope, how would I hook that up to the controller (I do have a Rigol but I'm an electronics beginner)?

Are we advocating that I just disconnect everything and take it apart, or try to test in-situ?

If I disconnect and move I will probably have to leave the acid pump in-situ.
 

Offline wasyoungonce

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Re: Pool controller
« Reply #16 on: April 08, 2018, 05:23:46 am »
Richard

When you did an acid test...did you pull the acid hose from the injector and check flow into a cup?  You mention the acid does not appear to be depleting is this over days or weeks or ?   Its possible the injector is clogged or peristaltic pump is not dispensing.  I have seen a clogged injector stopping flow broken pump rollers and cracked pump head shaft (plastic part).  Also, I did note on mine it had issues pumping acid when the Acid container was much lower than the pump...called "Head distance".   Others reckon that its fine with theirs but just say'in.  Easy enough to test...watch for moving bubbles in the acid tube if testing.

The controller is usually secured by 2 small screw heads holding it to the wall, you just lift up and out to move it.  You'll need to move it to open it.  You can drop the "tri acid" part of the system on the base easily but there are some hidden screws.  The controller can run fine without the "PH unit"...it was designed this way with the PH being an add-on "tri".

Yes, disconnecting it, that's the ticket....just take the acid  peristaltic head part off, 2 screws secure the head and pop off the pump head and 3 countersunk screws secure the motor (leave motor on if removing the whole PH unit).  The motor is inside the PH unit, it has a shaft with a flat land to align the pump head.  Lining this up can be a pain when re-assembling.  The motor is geared down so moving the gear shaft and motor is "difficult".

Take it apart...inspect for corrosion.  I suspect you have had your acid near the system...just like I did...and fumes permeate everywhere into everything.  I really should have tossed mine from said damage and I suspect I'll get strange faults from corrosion in the future.
« Last Edit: April 08, 2018, 05:26:57 am by wasyoungonce »
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Offline rthorntn

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Re: Pool controller
« Reply #17 on: April 09, 2018, 12:41:36 am »
Somebody asked me if the water flow is left-to-right, is my acid injection point to the left of the pH sensor, it is!!!

I can't see that stated in the manual but it seems obvious to me now.

I turned the sensor pod 180 degrees and it all appears to be working, pH is 7.1 because we manual dosed but I calibrated so that the acid pump came on and it kept running so fingers crossed that it's fixed.

Just wanted to let people know, in case they have the same issue.

Basically the plumber changed the configuration of the pipes and when he did that we should have switched the injection point, the readings were probably haywire because I was measuring the pH of a small pool of water that had just been injected with acid.
 
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Offline wasyoungonce

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Re: Pool controller
« Reply #18 on: April 09, 2018, 03:51:03 am »
Hmm the manual is specific about having the injector upstream of the sensor...but I wasn't sure on mine a way back and checked it.  if the injector is downstream...you you can get PH readings that are way off.   I have to ask...was this changed recently and upset the sensing? We are kinda not getting a full picture of events which makes it neigh impossible to follow.

Anyway just to be sure is acid flowing ok...can you see bubbles?

Well done, but I kinda get the feeling, just from experience myself and others, that this is not over yet!   ! :-//
« Last Edit: April 09, 2018, 04:09:11 am by wasyoungonce »
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