"I have a model with the orange sump, two years old. I noticed a very small hole in the transducer disk and after reading many of the messages on here I decided to try and change the 20mm disk before ordering a new transducer. ............... The replacement of the disk didn't work straight away. I had to open the transducer up again and make sure the disk was well centered and I also pulled the small spring up a little in the middle of the transducer to make sure that there is good contact with the disk . "
kd-bay >> First-time poster here. I've read many of these threads but the last few align closely with the success I recently found. Here's my take on what I think the important bits are.
- the ceramic transducer does have a lifespan so does wear out. Not sure how to test for this 'end of life'. But other factors may mask this.
- good contact is essential BUT as the transducer works at 2-3 MHz then DC resistance is not the enemy - ac impedance is. (IMPORTANT) i.e. ANY form of corrosion, limescale build-up etc will reduce the power into the element/transducer.
On my 3rd attempt to get a disk working, SUCCESS!. I did the following:
- disassemble and lay out all parts for cleaning (main unit with 'spring', slotted 'nut' (element retainer) with thin washer, element (transducer), main washer (under the element)
- using limescale remover / bathroom cleaner and a toothbrush, give the disc a gentle clean on both sides. Check for any limescale etc around the top side of the disc's edges. I used a flat bladed screwdriver to gently scrape around the perimeter of the disc. Then a final clean with the toothbrush. Then rinsed in water to make sure no deposits were left.
- using limescale remover / bathroom cleaner and a toothbrush, give the inside of the main unit a good clean - around the threaded parts where the 'nut' makes its contact with the body. The chrome came up really shiny !! A good sign there were deposits forming there, and that something had been removed. Rinse with water / toothbrush, dry with soft paper.
- dry the washers with tissue.
- I didn't pull the spring to increase pressure on the disc, but worth considering. Not sure I remembered to clean the END of the spring, but is WELL WORTH doing.
- Place all the parts in a warm place for 1/2 hr+ to ensure everything is dry.
- Place all the parts in a COOL place for ~1/2 hr to ensure everything is cool.
- Re-assemble whilst cool, so that when assembled and immersed into the water bath of the fire, it gets WARMED UP and creates a small positive pressure inside the unit, rather than cooling down and inducing a negative pressure hence pulling in water. Not sure if this is necessary, but gives it the best chance !
- Re-assembled, and placed in position in the water. Test with fingers crossed !!
Remember, I think combating limescale deposits etc is needed for the element to work correctly at ~2MHz. For EVERY point of contact from spring end, through the element, to the main unit housing. No deposits = clean & shiny metal. All food for thought really.
My 2nd attempt had been using the above process, but with a new element "JYD 7321" £2.50 from fleabay/UK which gave no joy !!! 2 discs for £1 now ordered from China. Just to be ready.
I'm indebted to those successful posters before me, in finding a path through this and reporting their findings. Time, and other success stories, will tell just what makes a 'correct fix'. Further info on replacement technique (details) and part numbers/URLs would be useful.
-kd-bay-
