How To Repair A Logix Controller - Replacing Back Up Capacitor on the Board
Last Updated: 05/27/2015
How To Repair A Logix Controller that Forgets the Time Of Day After Power Interruptions
The Logix Controller is designed to retain the correct time of day for up to eight hours after power interruptions. The time can be ‘remembered’ because the unit retains some backup power for the clock in a ‘supercapacitor’. These supercapacitors are like any other capacitor except that they have in very high values. After many years this capacitor may fail and your Logix controller time will reset towhenever power is removed.
One remedy for a ‘forgetful’ Logix controller is to replace the capacitor. This can be done by anyone who is handy with an X-acto knife and soldering iron.
Here are the step by step instructions:
1. Remove the Logix Controller from your softener. Removal is simple and covered in your softener manual.
2. Open the case...This part is a little tricky. The case of the controller is in two parts. The halves were glued together at the factory. Separating them takes a little work with an X-acto knife. Working on the back of the controller cut the seam all the way around the case. The knife is inserted vertically into the seam from the back of the controller. You have to cut all the way around the unit. Be careful not to insert the knife too deeply vertically into the seam so as to not damage the pc board inside.
3. The pc board can then be removed by taking out 4 small Phillips screws.
4. The ‘supercapacitor’ is the component marked “.047F” in the photo below. It is about 1/2 inch square.
5. The defective capacitor can be replaced by the one shown below. I purchased a package of 5 on Ebay for $10 including shipping! Be sure that you purchase one that is small enough to fit in the case. The one I used is .34 inches high and .5 inches in diameter (eBay description was: 5x 0.047F 5.5V Supercap; Memory Backup Battery Replacement Super Capacitor USA
6. With a fine tipped soldering iron, remove the old capacitor and replace with the new one. Get the polarity correct! On the capacitors shown here the double bars on the supercapacitor specify the case or negative side. The pc is marked with a + sign for the positive side of the capacitor. The round shape of this replacement required it to be mounted on an angle. It just has to be mounted such that it does not hit anything when the case is closed.
7. Parts are very close together on the back of the pc board. Be sure you don’t have any solder shorts...
8. Close the case and secure with something that will keep it closed. One method is to simply tape it shut with shipping tape as shown below.
9. Install the controller on your softener. Set the time correctly. Wait 10 minutes or so then remove power for a moment. The previous time setting should now be remembered despite the interruption.
* Special thanks to Mike M. for the instructions and photos he provided.
Tags: logix timer, logix timer program, power failure, time of day, power loss, memory, lines, 740, 742, 760, 762, valve type, model, reset, capacitor, super capacitor, back up
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