Puppythumpr
New member
Tank you for figuring this out!I just got a second hand Softub 220 (C-2013 board) with this same issue. Tub would do initial heat up fine but when it's around target temperature, it would turn on for a short time, then off, and repeat maybe every 15-30 minutes. The digital temperature indicator on the controller would fluctuate every second within a range of about 6 degrees. The temperature probes and control panel were replaced by the previous owner to try and solve this issue (which it didn't). I did some troubleshooting with a multimeter and noticed voltage fluctuations across the temperature sensor terminals (red/black). I added a 10uF capacitor on both temperature sensors and that solved the issue instantly. Temperature readings are now stable and correct, tub doesn't turn on/off constantly anymore. Perhaps this can help someone else. I didn't even solder in the capacitors but just shoved them into the holders, so far so good but something more permanent might be a good idea. I'm not sure what is causing these voltage fluctuations, perhaps it's interference from the motor that's not fully accounted for in the board design.
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I already replaced one board ($350) and it was doing it again within two years….
You fix cost me under $1….. Canadian!….. haha