Pool Solar Controller not working what part is this

[Uncle Fester]

there are 2 sensors pool and roof when I go to work I turn it on and during the day it starts if pool temp is under 28 but turns off when it gets 28 otherwise it could
be 32 by the time I get home.

Quote* Another idea is to also measure the voltage across the sensor input just when the motor switches on with the pot.
Lets assume the motor just switches on when the pot has a value of 2kΩ and you measure 0.7V across it.
Grab another pnp transistor and use 2k2 as the emitter resistor across the input. The collector of this transitor using a resistor of 2k2 to the negative of the capacitor with the blue resistor on the shown image posted below.
Now you can use pretty much any old NTC from Jaycar, I suggest 10k and connect it to base and +, NOT ground!
Then solder a 10k trim-pot between the base and ground and adjust until you get 0.7V over the emitter resistor.
You have now inverted the function of the sensor input. If the NTC gets lower the voltage on the input will get higher.

Sorry mate remember u are talking to a retired mechanic, most of this stuff goes straight over my head

When I did the measurement I dropped the end in a cup of water that was 50c , I will try it again using a lighter perhaps

thanks

OK so you just want it to switch off when the pool water reaches 28˚ but it won't always switch on because the roof sensor is faulty.

Aftter viewing the image more closely I can see that modification I suggested above will not work because the two sensors work in a bridge and the polarity swaps around. So you are relieved of that ordeal

I assume both sensors are the same.
Please measure now the resistance of the pool water sensor. First cold, then dip it in a cup of hot water like you did before. Do NOT hold a flame towards it.

My new plan is to connect a potentiometer(that roughly matches the value you measured) from Jaycar on the input of the roof sensor and find the point when it switches on while the pool water is cold.
The pump should stay running until the water reaches 28˚, you can use a cup of hot water(maybe higher than 28˚) and dip the pool sensor to confirm it switches off, may take a few moments for the sensor to respond. Also test if if stays running if the cup of water is a little less than 28˚ otherwise adjust the pot until it switches on again.

When that works and you have found the right pot setting all you have to do is get that thermostat switch:
and plug your controller through it into your power point. Place the sensor of the theromostat under your roof rubber and set it to switch on above 30˚.

Alternatively just switch on the system manually in the morning when it is sunny and you know somebody might want want to swim but don't forget to switch it off in the evening otherwise the pump will start running all night when the pool temperature drops.

Better use the thermostat.

[RedXT]

h8 dont worry about your lack of knowledge thats what we are here for its a question and answer site so even the silliest are answered so long as we are not getting jerked off we are happy to extend our minds even if they are old and a little forgetful results are what counts you should have realised that , please dont let it go over your head ,just ask and be honest we dont think of anyone as stupid by the questions . we manage to take a broad mind to problems dont be frightened to have a try to build your fault away to save a buck or two as we have all done it nomeat said he would modify his circuit so wait for him no worries ???

Thanks mate I can afford to buy a new one for around $300 but I hate throwing things out if they can be fixed
The information from u guys has turned a USLESS BOX back to a functioning device for about $2 and I have enjoyed the banter and advice probably more
than anything and was surprised that I got this far, I just dont want to waste peoples time.

I have got tomorrow off so I will test the other good sensor (pool) and see what I get as nomeat said and see what happens

Once again thanks everyone for the help

[hinekadon]

hi h8 we are glad to be of help your not wasting anyones time cheers don

[RedXT]

Tested the pool sensor today at 24C it reads 1.900k and at 50c it reads 2.320k so I guess both are the same just one screws in the pipe (pool)

[hinekadon]

take a look at this h8 so you need one of these on the roof , got the idea

heres where to buy

then we gotta work out which one suits your circuit ok progress
this will help

what was the reading on the existing roof one ???? cheers don
suspect its this one
/www.murata.com/products/productdetail?partno=PTFM04BH222Q2N34B0

[RedXT]

take a look at this h8 so you need one of these on the roof , got the idea

heres where to buy

then we gotta work out which one suits your circuit ok progress
this will help

what was the reading on the existing roof one ???? cheers don
suspect its this one
/www.murata.com/products/productdetail?partno=PTFM04BH222Q2N34B0

WOW looks like you have been working overtime
Great video I actually read some info from youre link to resistorsguide.com this morning
the roof sensor At 26C it reads 1.834k and at 46c it reads 2.220k

is this the same one

thanks thomo

[hinekadon]

yeah i think so? Thommo but Im a old fart so just wait for nomeat to confirm then we will be sure! .cant waste $2 now can we ? lol sometimes i can make a major fvkup and not realise it so some one to check is a good idea but i think im right,I havent been in this field for years ??? and things change over time and it does my old brain good to be worked again , on tuesday I was taken to a transmitter site where there are 3 fm stations on the one antenna and there was a problem with them interfering with each other had to scratch the nogging over that one as well but got it sorted so compliments were flying after that lol
ok lets wait for nomeat to arrive cheers don

[Uncle Fester]

Are you 100% sure? That is bad. None of the stores I am aware of have this. Element14 (Farnell) I keep getting access denied.

That actually included Ebay, my first choice of 'stores'.

The problem with all those PTCs is their switching character. They have a fairly constant start resistance until a certain temperature and then the resistance shoots up logarithmically.
I couldn't find a linear type like it seems to be used with this controller.

At first glance this one might look close:


but the problem is that it is 330Ω at 25˚C and roughly double that at 40˚C.
At 50˚C it actually reaches the 2kΩ we need but you miss out on all that hot water you could have got before.
You want it to switch on already at 30˚C and this PTC is way off.
Also a big problem is the sudden dramatic change it makes, especially if you would use several in series to make it respond better below 40˚C. This throws off the balance with the pool sensor.
That said it would be interesting if the system could work if both sensors were swapped with the PTFM04BH222Q2N34B0
but I am fairly certain that other components of the bridge would need to replaced, probably with a lot of trial and error and the logarithic behavior of these PTCs could end up saturating the input transistor. I think that would exceed h8fg4's scope somewhat

So sorry, I have to press the NO button here

I still think connecting a 5k pot or just a 2k2 or 2k7 resistor instead of the roof sensor to make sure the pump is switched on
and using a simple timer for your power point to make sure it doesn't run in the night or better that thermostat I mentioned above, would do the job.



PS: can you guys get past "access denied" when trying element14's Australian site?
https://au.element14.com/
A search for PTCs might still be interesting there.

[hinekadon]

yep i can get in there ? search for ptc ?

[hinekadon]

this is element 14 link but its 3kohms

[hinekadon]

link to mouser

[Uncle Fester]

link to mouser

No that link is to the one we already discussed. It has 330Ω.

I can't see any links to element14 >> access denied. I am a satanist

If it really has 3kΩ at 25˚C and shows a reasonable increase in the 30-35˚ we can work with it with a 10K trimmer parallel.
Could you post a screenshot?
or the actual part number

...and check the minimum order. Farnell have sometimes 100pcs minimum order

[hinekadon]

ttps://au.mouser.com/datasheet/2/281/datasheet_prfseries-1485179.pdf this has part nos on it and graphs "don

[Uncle Fester]

Well there is one with 1kΩ.
Two in series might work and from the graph at 35˚ it looks like we would then get at least 2.2k instead of 2k at 25˚, pretty good
but +/-50% tolerance and soldering SMD components might not be h8's cup of tea.

So using the selection guide I would determine the part number:
PRF21BG102XXXXX
The five X's are irrelevant for us, probably RB6RC or whatever is available.
BG102 is the important number.
It might be PRF15 instead of PRF21 but that would be like soldering a grain of sand.

So does element14 have this ?
I assume minimum order is 100 though but they may be only few cents each and you can fish out the ones with the closest tolerance to 1kΩ, ideally you might find two with 0.9kΩ at 25˚ room temperature.
It is actually not that hard to solder SMD. Just a tiny bit of veroboard with copper dots and solder each one between two dots. You would have plenty to try out and mess up until you get it right, it is fun

[hinekadon]

we have nothing to lose then . hey thommo get out your soldering iron hahaha see if you can get the afore mentioned PRF15BG102XXXXX from mouser then we are away with a cure by the looks of it , the idea is to join two together in place of the existing ptc so solder the two end on end then the wires to the ptcs and dunk in araldite and you have made the sensor . you will need about a 30/40w solder iron and some fine resin core solder hows that , a bit fiddly but im sure you can do it . What do you reckon don ????

[Uncle Fester]

They charge $9 just to cut off the reel ? and then postage?
10 for $3.44 is OK.

I can not guarantee this will work because i don't know how the system behaves when the temperature reaches Curie Point and the resistance runs away which is 50˚.
Then again the water in the heating rubber may never reach 50˚.

The cost of the theromstat and a resistor might be the same or less and will work.

[RedXT]

we have nothing to lose then . hey thommo get out your soldering iron hahaha see if you can get the afore mentioned PRF15BG102XXXXX from mouser then we are away with a cure by the looks of it , the idea is to join two together in place of the existing ptc so solder the two end on end then the wires to the ptcs and dunk in araldite and you have made the sensor . you will need about a 30/40w solder iron and some fine resin core solder hows that , a bit fiddly but im sure you can do it . What do you reckon don ????

as the saying goes "this is getting bigger than Ben Hur"
I have a soldering and magnifing glass , what have I got to loose ?
So I need the PRF15BG102XXXXX ?
Something like this ?

thanks thomo

[hinekadon]

thats a hell of a price hahaha yep 16 gives you a few to stuff up how do you feel about the project don

[RedXT]

thats a hell of a price hahaha yep 16 gives you a few to stuff up how do you feel about the project don

Correct me if Im wrong but reading this data sheet
tells me these things are about 1mm x o.5mm, to be soldered onto some tape as nomeat explained earlier, which I think might be beyond me.
How to solder SMD

I did find one solution this morning though
will see how the auction goes.
I might just have to bite the bullet and spend the cash on a new one, after all the old one lasted 18 years

Not Sure Thomo

[Uncle Fester]

as the saying goes "this is getting bigger than Ben Hur"
I have a soldering and magnifing glass , what have I got to loose ?

Only $25 but I give this a better than 90% chance it will work and you might not only gain a working controller but SMD soldering skills, priceless
16 should be enough to find a pair or two that add up to 1,8kΩ.

Correct me if Im wrong but reading this data sheet
tells me these things are about 1mm x o.5mm, to be soldered onto some tape as nomeat explained earlier, which I think might be beyond me.

Do not despair. Grab one of these as well:


As said, unlike the 21 pitch SMDs the 15er size is like a grain of sand. There is no way you can solder anything directly to them. The second you touch it with your soldering tip(even the smallest you can find) it will get sucked up, never to be seen again.
They are also very brittle. So we really need to do this on a Veroboard and it can be done.
Hopefully you got the good old lead/tin solder for electronics lying around. Do not use lead free solder.
Cut or snap the Veroboard to a smaller strip and solder in the wire bridges shown in black(you can use cut-offs from resistors) and pre-tin all the dots as shown in the image:






Try to place the thermistor between the solder dots so it is touching the edge of the dots and hold in place pressing it lightly down with the smallest watchmaker screwdriver you can find. Those cheap Chinese $2.95 sets you find in dollar shops are perfect.
Put a tiny bit of fresh solder on the soldering tip and quickly melt a dot next to the part without moving the screwdriver. Repeat for the other end.
The solder should flow smoothly into the component but you need to do this quickly before the rosin burns out on the tip.

Practice makes perfect. Try this out first on a bit of board with the out of range ones.
If you are shaky have a beer first

Use a cable ties to strap the Veroboard strip to your cable and cover it with epoxy.


...Of course you can chicken out and hope that other bidder didn't go to high