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Dimplex Opti-Myst fires

Discussion in 'Electrics UK' started by Neil B, 13 Feb 2010.

  1. JohnW2

    JohnW2

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    Am I the only person who wonders why, of the thousands of threads in this forum, this one seems unique in having been repeatedly revived, over a period of over 7 years, every time someone has had a question or observation relating to the same product as did that original post, 7 years ago?!

    Kind Regards, John
     
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  3. SimonH2

    SimonH2

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    Perhaps the Optimyst is (almost ?) unique in having been made for that length of time and the manufacturer doesn't seem to care about the problems with it ?
    Normally I'd expect a manufacturer with such a problem to have "fixed" the issue and over the 7 years the old ones would have gone and been replaced with something that works.
     
  4. JohnW2

    JohnW2

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    I agree with all that, but I was not thinking about the product or its manufacturer but, rather, the seemingly unique behaviour of forum members in relation to this one issue.

    Every week we see threads started which relate to very similar (or identical!) matters that have been the subject of countless previous threads - but, nearly always, an OP will start a new thread, rather than tagging onto one that has been around for years.

    It's of no importance, but I was just a little intrigued by this member behaviour. In terms of mechanics, I think one thing which allows this situation to persist is that posting a new message appears to 'reset the clock' which would otherwise warn attempted posters that "this thread is X years old". In other words, after someone has resurrected a thread, subsequent people attempting to post do not see something like...

    upload_2017-12-6_21-51-8.png

    Kind Regards, John
     
  5. ban-all-sheds

    ban-all-sheds

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    After someone has resurrected a thread it isn't old any more.

    "We may not bring them back to life, but we do bring them back from the dead".
     
  6. JohnW2

    JohnW2

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    That is true (in some senses), but I doubt that it would be beyond the capabilities of those in charge to change "This thread is more than 5 years old" to something like "This thread was started more than 5 years ago", and probably not beyond the capabilities of the software to make the message pop up at a time appropriate to the revised wording.

    Kind Regards, John
     
  7. ban-all-sheds

    ban-all-sheds

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    I'd rather they fixed the search and the weserv image mangling problems first.
     
  8. JohnW2

    JohnW2

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    Me too, but why not all three issues!

    Kind Regards, John
     
  9. kd-bay

    kd-bay

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    "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-
     
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  11. Lefthanded Pete

    Lefthanded Pete

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    I have a blue sump fire which I bought new in 2012 (at the cost of over £700 (yes they saw me coming) because my wife had seen a great review in her Saga magazine and wanted one - I stress that it was 'her' Saga magazine and not mine) which stopped smoking after two weeks. Dimplex took it back and sent a complete new fire (which is the one that I have now). It has only been used occasionally since then and not at all for the last two years. I only used distilled water but I never emptied it (I know) although I did regularly give it a good brushing around the seals (?) and the surface of the single disc in the sump. Fast forward to now, Wifey decided that she wants the fire going again so I switched it on and everything worked fine apart from the smoke which worked half heartedly for about 10 seconds after which the smoke faded away to nothing. If I take the top off the sump the disc thing is squirting the water a good 2" to 3" above the surface with splashes going much higher (so I assumed that that part is working correctly). I decided that maybe the fan was faulty so I bought (from Dymplex - £20) and installed a new one. The result - it smoked slightly more than half heartedly for a few seconds and then nothing, nowt, zilch, **** all! Wifey is quite upset that her 'lovely fire' has stopped working but I'm not prepared to spend nearly £200 for new guts which may or may not cure the problem. Does anyone have any ideas that may get it working again or is my best option to take the whole pile of **** to the tip when Wifey isn't looking?
     
  12. Sordids

    Sordids

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    Hello
    I have a dimplex BBK20 electric fire the bulb light up but no mist but after about 20 secs roughly the lamps turns off
    Is this the transducer at fault ?

    Thanks
     
    Last edited: 8 May 2018
  13. AlastairE

    AlastairE

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    Hmm--Sordids, Is that you from badcaps....?
     
  14. Sordids

    Sordids

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    Oh god it's a small world :)
    Hello mate
     
  15. AlastairE

    AlastairE

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    Ha! gotcha!

    It'll be the driver itself, the transistor goes short. Depends on which type you have, orange water-tank, (mister is not repairable, sealed potted thing)

    Or Blue tank, that is repairable, (TDK mist-maker board running 2.3MHz) On that board there's a shunt boost inverter from 12 to 24V ( this stage seldom goes unless water gets in through the really ****ty plastic dimplex used, this stage based on a JRC chip and MOSFET) and a single transistor power oscillator where the discs are the resonator, tuned by a open wound coil. Dodgy discs often cause the transistor to fail and take out a film cap as well....
     
  16. Sordids

    Sordids

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    It's the orange water tank one
    so are you saying it's the 24volt power supply transistor has shorted and also taken out the transducer mate ?
     
  17. AlastairE

    AlastairE

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    Unfortunately, Your type mister is the sealed/potted variety that cannot be repaired. You can buy a generic mist-maker/fogger for reptiles to replace your mister with, cost about £15, just measure the size of yours first, get one much the same to fit....
    Bit like this thing--
    https://www.ebay.co.uk/itm/Reptile-...203244?hash=item3f94315f2c:g:ob0AAOSwXsBahCd4

    The 24V supply in yours comes from the fire, the blue water-tank type generates it from a 12V supply, the orange and the blue tank fires are quite a bit different
     
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