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Steam Autoclave Board Repaired-Wax Applied To Microprocessor

By on March 23, 2021
Steam Autoclave Board Repaired

In this time I wanted to share with you this “Lessons Learned”. I have been “repairing” a cousin’s Steam autoclave 3 times… Same issue every time: Electronics get crazy caused by a water steam drop on a microprocessor. Which cleaned with a tooth brush and Isopropyl alcohol (IPA)… Then it works properly. The photo below is the autoclave (steam furnace to sterilize products).

steam autoclave repair

But 2 or 3 weeks ahead the issue is present again. I open the housing analyze and a white residue is again present on the bottom side of the microprocessor. Cleaned again and it works for 3 weeks approx. And again the same issue! This time I do something different.

Use the brush, clean with Isopropyl alcohol, let it dry… And light a candle!

light a candle

Light a candle to apply wax around the microprocessor IC.

This equipment will have always droplets or wet spots.

wax in microprocessor

apply wax to ic

Wax applied around the microprocessor pins and display’s pins. The idea is to avoid this to accumulate between microprocessor pins. Guess what…? It has been working for 2 months and no issues at all! I hope you like my shared experience!


This article was prepared for you by Francisco Maciel Barba from MacBar Re-Guadalajara, Jalisco, Mexico. Francisco is a Mechanical and Electrical Engineer and owns a shop in repairing SPA  Medical Equipment. He has been in this repair line for 15 years and love electronics since 12 years old.

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  1. B.R.Kobi

    March 23, 2021 at 7:16 pm

    Oh , very good idea. Out of the box thinking .

  2. Parasuraman S

    March 23, 2021 at 8:55 pm

    A good remedial fix!

  3. Albert van Bemmelen

    March 23, 2021 at 9:12 pm

    Very strange effect this steam drop of water has on the bottomside of the controller housing indeed! But did you remove the cpu from the board to see its bottom side that was covered with white calcium like residu? Since you covered only the top of the processor in wax it is confusing why you mentioned the bottom side of this cpu?

  4. Tayo

    March 23, 2021 at 9:33 pm

    Good solution. How did you figure out that it was steam/water on the MPU which was the root of the problem?

    • Francisco Maciel

      March 24, 2021 at 7:13 am

      First I analiyzed with a lupe and found the white residue on the lower pins of the IC.
      I fully cleaned with alcohol and check it worked OK.
      Then, apply wax all around to protect IC pins

  5. Andy Shiekh

    March 24, 2021 at 1:39 am

    I wonder if just using some silicone oil on the board would be enough, or perhaps some solder mask

  6. Francisco Maciel

    March 24, 2021 at 7:16 am

    Sorry for the translation issue. Pcb is always vertical. The white residue always were on lower pins (bottom side).

    • Albert van Bemmelen

      March 25, 2021 at 2:24 pm

      Understood Francisco! Thanks! Using "Below" instead of the word "Bottom" would probably have been better, as Bottom normally means the backside of a component. (like Top and Bottom view of for instance a transistor). Sorry for me asking the more obvious.

  7. moshe jacobsonqq

    March 24, 2021 at 11:23 am

    e x c e l l e n t solution...tha =nk you for sharing it.

  8. Yogesh Panchal

    March 24, 2021 at 3:45 pm

    Agree with Albert,Finding root cause and eliminate the problem is good for equipment's life.

  9. William Shaw

    March 24, 2021 at 10:32 pm

    That you were able to extend the period that it continues to operate was good, but I would think that no humidity should be getting to the electronics and it indicates a seal failure or design failure. What do you think?

  10. Lynn Blakely

    March 26, 2021 at 5:15 am

    Francisco Maciel: You did a good Job, thinking outside the box.

  11. ivan1

    March 27, 2021 at 10:37 am

    Existe un barniz spray .que además soporta alta tensión y temperatura, bien podría rociarse toda la placa con el ,pienso además incorporar unas bolsitas de silicato que viene en el embalaje de los electrodomésticos que viene precisamente para absorber la humedad en el interior de los aparatos
    There is a spray varnish that also supports high voltage and temperature, the entire plate could well be sprayed with it, I also intend to incorporate some silicate bags that come in the packaging of the appliances that comes precisely to absorb the humidity inside the appliances


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