Hot tub sensor swap

As I mentioned on the May Long weekend post I had to change the sensors on the hot tub.  I wanted to break this post out just so that people can find it in the future for those that are interested. I have a Polar Spa hot tub that is over 6 years old.  The name plate is wore a little and the model and dates are no longer present.  It is controlled by a Balboa M-series controller.

On the Friday of the May long weekend I opened up the hot tub to see a sensor error (code Sn).  This means that there is an error between the Sensor A (the inflow sensor) and Sensor B (the outflow sensor).  I called my hot tub guy up to find out what I could do about this.  Kyle over at J&J Service Tech in Calgary is a fantastic guy and answers my questions whenever I have them.  Kyle told me to shut the power off for 30mins to see if it would reset.  After the alotted time was over I turned the power back on and I got a Sensor B error (code Sb).  This code states that there is a malfunction with that sensor.  With another quick chat with Kyle and I found out that he did not have any sensors left as it is a busy time of year for getting hot tubs operational.  He suggested a few places that I try that I might find them.  He told me the part that I was looking for was the M7 Sensor.

Armed with my knowledge I set out to find the sensors.  After a quick google search and some waiting for stock checks I found some.  I figured if I was going to change one I might as well change both.  I drained the hot tub to below the heating tube.  You do not need to completely drain the hot tub, just make sure the water line is below where you are working.  I pulled the cover off of the controller and traced the lines from the sensors to their connection points on the board.  The circuit diagram is printed on the inside of the controller cover, and I always double check what I am working on is what the diagram says it is. 

Here are where the two sensors are located at.

Change the sensors was easy, just unthread and unplug them .  Then thread in the new one and plug it in the correct spot on the board.  I tucked the wires out of the way and put the cover back on.  I refilled it and turned the power back on.  It takes a minute for it to initialize then it indicated that it was operating correctly.

If you have any comments or questions please share below. You can also follow me on twitter at https://twitter.com/@bjshideler

S is for Solder vs Crimp

S is for Solder vs Crimp

In the amateur radio world there is a great debate over which is better to solder or to crimp, this goes into coaxial cable as well.  For the old timers they like the strength of solder in that there is a fused connection between the two pieces of wire or the connector.  This connection will provide the electrical continuity that is being looked for.  The downside to these connections is that with the hard connection that repetitive motion of the wire at the joint could also make the joint break at that location over time.  Another weakness of solder is that if there is enough heat either due to resistance (too much current) it will melt the solder and you will lose the connection.

The alternative to soldering is crimping.  Crimping provides a connection that relies on friction to keep it together.  Crimping is really easy and quick, also it is a lot more portable than trying to take a soldering iron to wherever you want to make a connection.  For example I was on the roof last fall installing an antenna and I needed to put an end on it.  It would have been very awkward to pull up the extension cord and my soldering iron up there and waited for it to heat up and shield it from the wind as it is only a cheap 30W iron and hope that it would have worked.  Instead I pulled out my crimpers and made the connection in less than a minute.  People are afraid that if you got water in the connection it would cause it to corrode and not be as electrically sound or that it will pull out no longer being connected.  To alleviate the corrosion issue you can put some dielectric grease which is used in car spark plug wires to make sure it makes the connection.  By covering the joint in grease it will keep the water out of there.  The best way that I have found to make sure that you get a good connection is to have a set of purpose built crimpers, not the all in ones from Radio Shack.  I have found some pairs for a really good price and then make sure that the crimp is on all sides and that there is not a place for the wire to wiggle out of. 

From my experience at work in both high and low voltage there is no soldering, neither in automotive, I am also told that it is forbidden in the aviation world.  NASA will use solder in their lineman’s splice which because of the single use nature of a mission build there is not a lot of repetitive strain loading on the wires for it to fatigue.  Now back when the linesman would use that splice on telegraph wire they did not use solder.  The only place I have come across solder is in electronics, which is too small for crimping.

Anyways, there is some background on the age old debate.  Share with the group whether you prefer to crimp or solder. 

If you like what you have read, please subscribe to the blog, or follow me on twitter at @bjshideler. Also, share this post with your friends on your favorite social media sites.