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RZ3: SL32 Thermistor
Posted by hazmat on 5/20/2012 at 5:51 PM

hazmat
Doing some troubleshooting on my generator and found this site- unfortunately the simple fix didn't help - there were no burnt traces, the board looked fine. There was some browning of the PCB near RZ3, which is an NTC (Negative Temperature Constant) Thermistor- After removing, checking, and re-soldering the relays, finding nothing, I started looking elsewhere.  I measured the voltage across RZ3 and found it to be about 7V- according to the specs on the Ametherm website, this is *way* too much voltage across this component- I believe it has failed.
 
FYI: I am an electrical engineer and I work with high voltages/current everyday. THIS IS NOT FOR THE AVERAGE USER: I shorted RZ3 and the generating light came on. I believe that the thermistor has failed. On my board, this is labeled SR32 2R025.  I found this at Digi-Key: <http://search.digikey.com/scripts/DkSearch/dksus.dll?WT.z_header=search_go&lang=en&site=us&keywords=SL32+2R025&x=0&y=0> at $2.69 ea (qty 1).  After shorting this out, the current read about 4.25A (a little low, but my short isn't perfect).

This is a safety related component- BE VERY CAREFUL. In fact, if you find this problem, just replace the board. However, if you don't care about the safety (or lives) of those that swim in your pool, and want to save a few hundred dollars, this information might prove interesting.
Posted by Loni on 5/20/2012 at 7:34 PM

Loni
Shorting it, jumping it, whatever, IS a safety issue that I too would NOT recommend. As you are an electrical engineer I am confused why you chose NOT to replace the part. You had to have gotten some experience at component-level replacement in the early stages of your education, no? Is it the shipping/handling or minimums? I'll ship you one for 6.50, if that's the case! 
Posted by hazmat on 5/20/2012 at 10:29 PM

hazmat
The short was just a temporary kludge to diagnose the failed part- I ordered some of the parts- I had other things to get from Digi-Key. Thanks for the offer for the components- You ought to make your Ebay store easier to find- I was about to order a whole new board, wasn't sure which seller was you, then decided to do a bit more diagnosis! 
Posted by Loni on 5/21/2012 at 1:07 AM

Loni
Thanks for the advice! I don't have a store on eBay, and this is only my second listing. But I just set up a store (with more to come) on eBid.net. A fraction of the fees, but also a fraction of the traffic. Other benefits made this an attractive supplement/alternative to eBay; and I can link my sites to the stores and have an easy solution to my whole shopping cart and ordering problem. They allow you to do way more than eBay does. I've almost literally been chained to this computer (or another) for weeks doing research, reading, setting things up, and getting my other websites live and ready to make all of your ears ooze with new-found knowledge of your pool stuff ;-)

...I'm workin' on it, boss!
Posted by hazmat on 5/22/2012 at 5:08 PM

hazmat
An update on my problem... I fixed it!  My "power" light is on, and the "generating" light is on!  I removed the old thermistor and it reads about 27K Ohms- when it should read 2 Ohms (when cold)- About 10,000 times higher resistance than what it should be! After thinking about this, I'm not terribly surprised that the NTC thermistor failed- heat is the enemy of electronics, but this component runs hot *all the time*.

The thermistor is a cheap, easy way to control the inrush current, but considering just how much this board sells for, I think that we, as consumers, should have a better circuit. In bulk this component costs *way* less than $1.00- it is probably far from being the most expensive component on the board (the relays probably are the most costly). Unfortunately, considering how this part is operating, it is virtually guaranteed to fail eventually, but probably after the warranty has expired.

Good luck all. Be very careful when doing any circuit modifications. Looking at the circuit, I don't think RZ3 is any more (or less) safety related than other components on the board- but still, any changes run some risk.  You'll be safest if you just drain your pool and fill it full of potting soil and grow some flowers.
Posted by Loni on 5/22/2012 at 7:30 PM

Loni
There is a site that is just like this one, but for Aqua Rites - http://idoneitmyself.wordpress.com/2009/08/23/repairing-my-aqua-rite-that-was-damaged-by-lightning/. Actually it's a blog, and it doesn't get nearly the action that this site does. Still, I've tried to help out there a bit as well. This is the most common problem with the Aqua Rites. They use the varistor/inrush current limiter/whatever you want to call it to direct the heat generated away from the board. The tell tale sign is hairline cracks on it, that may not be readily seen with a magnifying glass, especially on the thin edge.

Starting with rev 1.50, they redesigned the board, and use a different varistor/inrush current limiter/whatever that is MUCH beefier. I'll be stocking those soon for those that INSIST on doing it themselves. Still, I have had to replace a couple of r1.50 or greater boards (at least one under warranty) for the same issue.

Naturally, being in the biz, I hear the "fill it in" a lot. Did you know that you can't just fill in your pool with anything other than concrete, without first having holes punched in the bottom for drainage (thousands of $). The EPA does not want any swamp-like breeding grounds, and without drainage into the ground and water table, that's exactly what you'd be creating.
Posted by johnastephens on 9/22/2013 at 11:18 AM

johnastephens
goldline aqua-rite diagnostic voltage 4v current 0. checked voltage across RZ3 high indicates RZ3 open. After taking a closer look at RZ3 I saw cracks on the component. Ordered RZ3 thermistor from Mouser. Will replace on Monday. I'm about 99 percent sure that this will have solved the problem.

I have seen many posts that indicate that making repairs yourself insinuate that you could endanger people in the pool. This is bullshit and someone trying to profit from your misfortune.

When removing the component try a solder sucker (can be purchased on ebay for a couple dollars) In my 50 years of  experience solder suckers work best. far better than braided copper. A solder sucker will last years and will be their when you need it again.

Go through the diagnostic's a couple time a week and get familiar with what readings you see. It only takes 30 seconds. That way you will catch problems before your pool turns green.
Posted by johnastephens on 9/22/2013 at 11:19 AM

johnastephens
goldline aqua-rite diagnostic voltage 4v current 0. checked voltage across RZ3 high indicates RZ3 open. After taking a closer look at RZ3 I saw cracks on the component. Ordered RZ3 thermistor from Mouser. Will replace on Monday. I'm about 99 percent sure that this will have solved the problem.

I have seen many posts that indicate that making repairs yourself insinuate that you could endanger people in the pool. This is bullshit and someone trying to profit from your misfortune.

When removing the component try a solder sucker (can be purchased on ebay for a couple dollars) In my 50 years of  experience solder suckers work best. far better than braided copper. A solder sucker will last years and will be their when you need it again.

Go through the diagnostic's a couple time a week and get familiar with what readings you see. It only takes 30 seconds. That way you will catch problems before your pool turns green.
Posted by johnastephens on 9/22/2013 at 11:26 AM

johnastephens
Soldering tip. If you have a pine tree in your area get some sap from the tree. That is rosin and does a good job in cleaning your soldering gun tip.
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