These supplies are awful. I fixed one myself.
The failure mode is that the primary cap goes bad (leaking electrolyte etches one of the connections away). The supply has PFC, which is a step-up converter outputting 400V into that cap. If the capacitor is suddenly disconnected from the circuit, the PFC coil discharges into, well, there is nothing to discharge into, so it kills the primary switching mosfet. The MOSFET fails by shorting all terminals, thus shorting the primary side. The 0.22Ohm resistor is a fusible resistor (which doubles as low-side current shunt), which blows and opens the circuit to, err, not really prevent any damage. As soon as the 0.22Ohm resistor is blown, the gate of the FET is connected to the unloaded full-wave rectified mains input. The PFC controller IC (an LT6561) is not very fond of getting fed +300V on its gate driver and blows, too.
Further collateral damage usually is created by shorts inside the PFC controller IC that apply high voltage to some SMD resistors and transistors (In my case, a 1k 0805 resistor and a SMD PNP transistor, which has been replaced by an MMBT3906). It is said on forums that sometimes a zener diode fails, too. A lot about fixing these supplies (also used in th Dell 2407, and if there is a 2406, in that one most likely, too) can be found in different forums, for example the badcaps forum.
After swapping these parts and applying power, nothing happened, because the input fuse was blown too. Fixing the fuse made the primary bridge rectifier go boom (likely it already had one diode shorted). After swapping that one too, the supply worked again.
The desing of that supply is quite interesting: Because of European Union regulations, devices consuming more than 75W need to have a good power factor which can be obtained by big chokes or active PFC, on the other hand, a PFC circuit increases quiescent current and thus may greatly reduce standby effectivity. This supply bypasses PFC in standby, and enables it in usual operation. As there is a diode (check that one, too...) from the bridge recitifier output to the main filter cap that conducts if the spontaneous rectified mains voltage exceeds the cap voltage, the PFC can be bypassed by just disabling the PFC controller chip. If I remember correctly, that's what the blown transistor was for.
I think the output of the supply is 19V only, so replacing it with a cheap laptop supply might be an option. There are hacks on the internet about modifying the supply to allow external power input on the speaker bar supply jack.
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