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USN 52 Krautkramer Branson Flaw Detector Battery Charging Circuit Repair

By on November 7, 2017
Ultrasonic Thickness Meter circuit board fix and repair











A New customer brought this in today and he told me he heard that I repair these types of equipment. What this is, is an Ultrasonic Thickness Meter, also known as a Flaw Detector. It measures the thickness of Steel, Stainless Steel Etc. This piece of equipment is used mainly in the Oil and Industry to measure the thickness of Steel vessels and Oil Tank wall thickness etc.

The Customer said that the equipment works off the power adapter but it does not work of the battery power. So, he asks if I could repair it and calibrate it for him. I said I would have a look at it for him. The picture below is the front of the equipment.

USN 52 Krautkramer Branson Flaw Detector Battery Charging Circuit Repair

USN 52 Krautkramer Branson Flaw Detector Battery Charging Circuit fix

This is the Battery compartment for the batteries. The first thing I did was to test the equipment with the AC adapter and indeed it was powering on as he said. Since I did not have the batteries I used my power supply and feed an 8.6 V DC to the battery input and it did not work as he said. I first suspect the Charging circuit could be faulty

Ultrasonic Thickness Meter repair

I then open the unit by removing 10 Screws and the below picture is the circuit boards that were inside the unit. As you can see there are four Circuit boards in this unit. Starting from the bottom is the display board then the main processing board, then the power supply board. The last small board is a digital processing board.

Ultrasonic Thickness Meter circuit board repair

After looking around the boards and tracing the wires that feed from the battery compartment, I could see that the Battery was feeding the Jack on the left side of the board below which is the third board.

how to repair Ultrasonic Thickness meter

Looking at the board I could clearly see some burnt components on the board and my guess was right, it was the charging circuit that was faulty. Below is are the bad components indicated by the arrows. It was a two electrolytic caps 330uf – 16V and 100uf – 16V, two 100uf – 20V Tantalum caps and LT1070 which is a 5A High Efficiency Regulator.

how to fix Ultrasonic Thickness meter

This Tantalum capacitor was Crack badly.

What I think had happen was the owner used another type of batteries to power the unit and it immediately blew the circuit.

how to fix USN 52 Krautkramer Branson Flaw Detector

Here I removed all the bad components from the board and you can see the scorch marks on the board, I hoped that it did not burned the boards and I was lucky enough that it didn’t.

how to repair USN 52 Krautkramer Branson Flaw Detector

These are the Bad parts.

bad parts

I did not have Tantalum capacitors so I use 100uf – 50V Electrolytic Caps instead. Once the parts were replaced and I assembled the unit together for testing. Using my power supply again and powered the unit it came back to life.

fixing ultrasonic thickness meter

Then I used the power adapter to power the unit and check the output to the batteries and indeed it was working fine now. Check the below picture for the voltage that will be supplying the batteries.

gwinstek gdm-8251a meter

I then Calibrated the unit using a Step block which measured at 0.25 to 1.00 inches. Mission accomplished. The customer will be very happy.

This article was prepared for you by Andre Gopee from Calitech Limited Trinidad West Indies.

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By the way if you have any good repair article that you want me to publish in this blog please do contact me HERE.

Note: Please check out his previous repair article below:




  1. Andre

    November 7, 2017 at 9:21 pm

    Hi Andre

    Thank you very much for sharing the product repair. How do you calibrate this unit and what is a step block?


    • Andre

      November 7, 2017 at 10:16 pm

      Hi Andre, A Step block is a Piece of Steel or Stainless Steel which is cut out precisely to measurements like .025" to 10" or so, in a Step manner. You can get these block for any thickness you want and you use this block with a Probe which plugs inti the meter and the meter should read the exact measurement of the thickness of the block. If it does not you will have to go into the meter menu and perform a calibration.

    • D. Wilson

      November 8, 2017 at 4:32 am

      I thought that tantalum capacitors were non polarized and therefore would have to be replaced by a unit that is also non polarized. Thanks for sharing your experience. Be blessed.

      • Andre

        November 11, 2017 at 1:42 am

        Hi Wilson, Tantalum capacitors are polarized. If you look at a Tantalum cap you will see a positive marking on one side. some are indicated by a line and some with a positive sign.

        • Robert Calk

          November 11, 2017 at 7:57 am

          And some have the cathode marked with a line and some have a negative sign. You have to be careful with Tantalum caps and do a little research. If anyone is not sure what type they have then Wikipedia would be a good place to start investigating.

  2. Parasuraman

    November 7, 2017 at 10:46 pm

    Yes, I too had the same doubt. How did you calibrate it? Is there any pot?

    • Andre

      November 11, 2017 at 1:45 am

      Hi Parasuraman, no there are no pots to calibrate this meter, calibration is done via software built in the meter. When you apply the test probe to the Standard you will enter the value of the standard via the calibration program on the meter and save it to memory.

  3. M.Jais

    November 8, 2017 at 12:53 am

    Hi Andre
    This flaw detecter....
    The price rm15k to rm30k/unit....
    One of the type Non Destructive Testing....
    Thank you very much for sharing....

    • Andre

      November 11, 2017 at 1:50 am

      MJais, yes these meter are quite expensive and even shipping it back the manufacturer is also quite expensive.

  4. Jim Whalen

    November 8, 2017 at 3:59 am

    Nice going Andre,
    and a step block is a small metal square cut with small steps to be able to measure different thickness

    • Andre

      November 11, 2017 at 1:51 am

      Yes it is exactly that.

  5. mahmoud_tajpour

    November 8, 2017 at 4:19 am

    HI dear Andere very excellent repair.

  6. D. Wilson

    November 8, 2017 at 4:35 am

    Please let me have some details on the reasoning supporting the usage of the electrolytic in place of a tantalum. Thanks.

    • Andre

      November 11, 2017 at 1:54 am

      Wilson, the reason I use an Electrolytic Cap instead of the tantalum is just because I did not have a Tantalum at the moment and the customer was very eager to get back the equipment for a job he had. I have since ordered the tantalums and the next available time in comes back in for calibration I will replace the Electrolytic with the tantalum.

  7. Albert

    November 8, 2017 at 8:42 am

    Nice Job Andre, I wanted to ask the same questions as my previous reader(s) already did. Because calibrating in inches is not soemthing we engineers normally do.

    • Andre

      November 11, 2017 at 1:56 am

      Albert, in our country we use inches as well as mm. Its a preference of the customer requirements at the time. I have both inches and millimeter block for calibration.

      • Robert Calk

        November 11, 2017 at 8:01 am

        Here in the USA is the same way. When I was a mechanic I had to have tools for both SAE & Metric. I prefer the Metric system.

  8. Jai Etwaroo

    November 8, 2017 at 11:14 am

    Nice work Andre

  9. Robert Calk

    November 8, 2017 at 6:36 pm

    Nice job, Andre. I have never seen one of those before.

    • Andre

      November 11, 2017 at 1:59 am

      These type of equipment are mainly use in the oil and gas industries in our country. but most factories who has pipe lines and storage tank will also use this equipment to measure the wall thickness to ensure it meet a particular standard. It is a requirement by national standards.

  10. Yogesh Panchal

    November 10, 2017 at 11:19 pm

    Andre Gopee,

    Good work!

  11. Justice

    November 13, 2017 at 9:21 pm

    Thanks Andre great job.

  12. kevin

    September 20, 2018 at 1:17 pm

    I have exactly the same issue on exactly the same UT Flaw detector.
    Thanks very much for posting your experience and fix.

  13. Zvone

    June 1, 2022 at 4:25 pm

    On the power connector jack, what are those 7 pins used for?


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