Transformer Rewinding for Ultrasonic Power Module

This week I worked on an Ultrasonic Power Module ( Artech Ultrasonic DGS35-200-T ). It is a 200 watt power module that produces frequencies in the range of 30 – 38Khz. It is coupled to 2 transducer heads that shakes very fine screens in order to filter ceramic dust.

Ultrasonic Power Supply

The unit came to us because it had blown up. The switchmode transformer was cooked and the power mosfets had been destroyed. I removed the blown tranformer and power mosfets, traced the power circuit and tried to locate replacements.

Burnt Transformer
The mosfets were not available in Australia and with the machine causing production issues I found other mosfets with similar ratings to do the job. The transformer had some numbers on it but no hits on the net apart from the core material.

Transformer core with chip

The E shaped core had a chip out of it so the core had to be replaced along with the coil former. I was able to locate the same size core and coil former from Radio Spares. I unwound the transformer and recorded the winding details. The windings had 30 strands of 0.1mm diameter wire. After many phone calls I was unable to locate Litz type wire to do the job, so I had to make my own. I could only get 0.15mm diameter, so used this with less strands to get the job done.

Power Module ultrasonics schematic

With the transformer rewound, mosfet drive circuit traced and repaired, soft charge resistors and soft charge bypass relay replaced it was time to test. I was unable to do a low voltage test on this unit so it was ‘go for broke’ full 240v ac test.

Rewound transformer

Hooray, testing was successful!