Dometic SinePower DSP 1812T - No AC output

[smilgy]

Hey All,

I have a Dometic DSP 1812T 1800W inverter with no 230V output. Previous owner said they plugged in a 2300W kettle and then it stopped working.

I've taken it apart and found a manufacturing fault where the manufacturer forgot to put in some screws to attach the 12V DC side mosfets to their heatsinks. Naturally, these failed.. I can easily replace these, however want to know what else may have been damaged in the process?

The inverter still worked in the sense that it would power up, display ON light, and some relays clicked.


I may have damaged a couple of pads on the mosfets, but fairly sure they're salvageable, so not too worried about that for now.

Any thoughts? Not terribly familiar with inverters so would appreciate what to check next!

[CapLeaker]

Mosfets are toast, replace them all. Do not reuse an old one even if one survived. At least always replace them in pairs. Once the mosfet shorted it gave full power to the gate drive. Inspect all the components from the mosfet down to the (and including) the PWM.

[smilgy]

All mosfets replaced. Majority of them were gone. Also some 22R1 SMD resistors beside the mosfets were dead as well, so I replaced them too.

The unit now has more life than it did previously, which is good. It gives an AC output of 270V using a normal multi meter or 145V with a true rms meter for about 15 seconds or so, before the unit shuts down (you can hear a relay click).

I'd did then check some downstream components, but didn't find anything obvious? I have a thermal camera, but nothing obvious comes up either.

Any suggestions?

[CapLeaker]

Sounds like it can't regulate or is miss aligned somehow. Your DMM is off, since 270VAC on the oscilloscope does not equal 145VAC RMS should be like 170VAC RMS. It probably shuts down because the output voltage is incorrect.