Dometic SinePower DSP 1812T Inverter

[smilgy]

Hey All,

I have a Dometic DSP 1812T 1800W inverter which has no 230V output. Previous owner said they plugged in a 2300W kettle and then it stopped working. Initial symptoms were no 230V output, however the unit would turn on, and internally some relays clicked.

I've taken it apart and found a manufacturing fault where the manufacturer forgot to put in some screws to attach the input DC side mosfets to their heatsinks. Naturally, these failed. I have replaced these along with some nearby SMD 22R1 resistors. I've replaced all 12 of these mosftets and resistors. Putting it back together, the inverter shows a little more life, there is now an output on the AC side, but after about 10s, a relay clicks and the output is turned off. Measuring the output, it measures about 145V on a true RMS meter, or 270V on a cheap DMM.

When the output is turned off after approx 10s, you can very faintly hear a sort of clicking or ticking noise (but not a relay!) from around the step up transformer area. I've marked it red on one of the photos.

I've done a reasonably thorough check of most components for shorts, but cant find anything obvious. I have a thermal camera, some basic meters, but unfortunately no oscilloscope.

Any thoughts on where to go next? Apart from this fault, the unit is reasonably new and wouldn't have had much use.

[indeterminate]

Replace the gate drive ic's

[smilgy]

Replace the gate drive ic's

I've had a look at the gate drive IC, and I'm not 100% sure that it is malfunctioning/bad. Its a TI UCC27324DR cirlced red on the photo attached.
https://www.ti.com/lit/ds/symlink/ucc27324.pdf?ts=1727981526281&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FUCC27324%252Fpart-details%252FUCC27324DR

There doesn't appear to be any shorts on it, and thermal image doesn't show it heating out of the ordinary. However, I may order one and replace just to see.