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Monday, 27 March 2017

Aquarium Chiller Resun CL650- Erratic Temperature Readings

27 March 2017

The chiller  controller has erratic temperature readings.  It fluctuated between 3 to 4 degrees C erratically.  As a result,  the chiller did not start and stop properly.  Otherwise,  the Chiller worked normally.

What Could Go Wrong?

 1.  Dry Joints -  They are often responsible for erratic performance and often give erroneous readings;

 2.  Faulty Capacitors - They will lost the filtering and cause voltages to fluctuate;  thereby,  giving erroneous temperature readings.

How to Dismantle and Remove the Controller?

The controller is flushed mounted with a dust protective plastic cover in the inside of the chiller casing.  The cover is secured to the chiller casing by four clips evenly distributed around the peripheral of the plastic cover.

To remove the cover,  one will need to push the clip inwards using one finger and pull the cover down at the same time using another hand.  Releasing the clips will need some care and patients,  releasing the clips one at a time.  Some reported that there might be four screws securing the plastic cover and they must be removed first.

Once the plastic cover is removed,  one can pull up the controller from the top of the chiller casing.  Observe and make notes on how the wirings are connected.

What Went Wrong?

Bench inspection suspected that there are a few dry joints.  However,  resoldered those joints did stabliise the readings and prevent much voltage fluctuations in the supply line but the controller continued to give erratic readings.

Finally,  bench testing proved that one of the two capacitors shown below had a deteriorated capacitance giving only 15 uf instead of the 400 uf.  Replacing the 400 uf capacitor fixed the erratic reading.

Degree of Difficulty

It was  not difficult to replace the capacitors but the 2 tier circuit board arrangement made de-soldering and soldering pretty difficult to carry out to test and replace those capacitors.

What to get a Replacement?

For those who need a replacement for the controller,  they should be able to find it on TaoBao (link) for about RMB200.  Write to them make an enquiry at this website.  Alternatively,  one could replace the controller.  

 Other Relevant Sites
tinyurl :


  1. Hi! i have the CL450 and come into this problem, i remove everything and the capacitor seems in good shape, presumably i need to change it, where can i find one that does for me, im not good in soldiering. Which Particular in SLT can i find this? i can't use my chiller since 2days ago and desperately need it done. many thanks!!

    1. I suggest you comb through TaoBao or Aliexpress searching using the ratings written on the capacitor..If you want to try your luck, you could go to a basement shop at SLT.. the last I checked, the capacitor costed me twice as much compare to buying it online.


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