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USN 52 Krautkramer Branson Flaw Detector Battery Charging Circuit 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.
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
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.
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.
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.
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.
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.
These are the 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.
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.
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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Note: Please check out his previous repair article below: