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Water Damaged Equipment Repaired

By on April 6, 2021
dental equipment repair

A dentist walked into my shop carrying an expensive dental device and wants it to get it fixed as soon as possible. It is a device that has to do with teeth planting. I have not worked on such machines before but I was willing to help the guy out.

how to fix dental equipment

As I took the top cover off I was able to see the inside of this machine.

There is another board that has the device controls on but it was not the main issue here because the main fault in the device is dead due to water damage. Let us find out.

fixing dental device

how to fix and repair dental device

The two previous photos show the big water damage that this device was exposed to. The first thing to do is to clean the board then look for faulty parts due to this water damage.

dental equipment circuit board

dental device repair

After the cleaning was done, I started looking for faulty parts and I started that by separating the power in board from the main board and connected it to a power source and to my surprise AC voltage were coming out.

dental device repair and fix

stp40n10l datasheet

Click here to access the STP40NF10L Datasheet

Since both fuses were open so I headed to the bridge rectifier and looked for faulty parts there.

The bridge rectifier was ok but the two Mosfets next to it were both shorted.

capacitor shorted

These are the two capacitors near that area of the damage. It was also cleaned and new capacitors were added there.

I looked for a replacement for these two shorted Mosfets but I could not locate them anywhere in my area but I was able to find them online. I informed the customer and he was not happy about it due to the fact it is going to take at least 25 days for the parts to get here for this device was urgently needed in his clinic but he had no choice.

dental equipment fix and repair

Finally, the parts were here and were soldered on board and tested (I cut the Mosfets pins later on).

Mission Accomplished.

This article was prepared for you by Waleed Rishmawi, one of our ‘Master Authors’ and currently working in the Bethlehem area of Palestine repairing electrical and electronic equipment.

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Note: You can check his previous repair articles in the link below:



  1. Albert van Bemmelen

    April 6, 2021 at 7:42 pm

    That was serious water damage you had to fix! Recently I noticed that I was easily able to clean corrosion of battery contacts in a Satellite remote controller by brushing the corroded springs clean with WD40. And after that I used some cleaning spirit (Dutch : Wasbenzine) to degrease the left residu of the WD40 liquid spray away from the board and the contacts.

    • Waleed Rishmawi

      April 6, 2021 at 9:06 pm

      Albert: yes, it was really bad. the device uses water when doing the drilling so the water was going inside the machine and that is how it got damaged by water. have a blessed day

  2. Parasuraman S

    April 6, 2021 at 11:43 pm

    Good job there on a new device! I was interested because it was a medical equipment! Many thanks for sharing!

    • Waleed Rishmawi

      April 7, 2021 at 1:08 pm

      Parasuraman: you are most welcome my friend. Have a blessed day

  3. Paul

    April 7, 2021 at 5:53 am

    What you used for the cleaning?

    • Waleed Rishmawi

      April 7, 2021 at 1:06 pm

      Paul: IPA alcohol and a fine steel brush. Have a good day

  4. Yogesh Panchal

    April 7, 2021 at 2:41 pm

    Good fix! waleed,
    I also returned some job to customers because of unavailability of spares.

  5. Waleed Rishmawi

    April 8, 2021 at 2:45 pm

    Yogesh: thanks man. The unavailability of parts is one of the most bad things in the repair field. You spent a lot of time on finding the issue but end up returning the device because there is not parts for the fix. in my shop right now, I am making a list of parts needed in the shop and I am ordering stuff like crazy and in quantities. you never know what comes your way and if you have the stuff available you go a long way. have a blessed day

  6. Humberto

    April 14, 2021 at 8:48 pm

    Medical sets are very expensive. The dentist must be very happy now.


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