I can tell the story now that it's reached a conclusion.
About ten days ago I was asked to set up a brand new Dell 3668 compact PC for a lady who'd brought it back from New York and clearly I was thinking it would be a walk in the park and I'd go away leaving another happy customer.
Having connected up the cables for the keyboard, mouse and monitor, I then inserted the power cable and was rather surprised by the sparks and smoke that suddenly appeared, all this in front of the customer too.
I'm so used to connecting up power supplies that I didn't look to see that Dell puts switches on theirs for 110/230v. Most are now auto switching.
Anyway, for the next week we explored possibilities of friends coming over from NY, availability at Dell and I even managed to get a price from a Dell dealer in Galeria Jardin which took the notion of being shafted Argentine style to a whole new level.
Then it dawned on me - you can get almost anything repaired here, which led me to Mercadolibre and a company, Trans Power in San Martin who agreed to look at it, much to my relief.
You have to bear in mind how excited the lady was, having got it through EZE customs in the first place and being an Intel i5, 8Gb Ram, SSD etc, it's (or potentially, was) one heck of a machine.
I was delighted to receive a message from Trans Power last Friday saying they could repair it by replacing the voltage regulator and a number of other components that had blown. My biggest worry at this stage was whether the motherboard had been damaged, but this being a Dell, there was no way to test it other than with this power supply.
After a few anxious days I picked up the PSU this afternoon from the boss of the company, raced home on my bike and gingerly connected everything up, willing it to come to life, which it did as if nothing had ever happened.
As you can imagine, I breathed a huge sigh of relief and will be taking it back to the customer tomorrow morning and double checking again that the tiny red switch is set to the correct position.
That's a valuable lesson learned and it's worth noting that a replacement PSU from Dell USA would have been around $150 and around $250 here. The cost of the repair was AR$800 (around US$30).
Naturally I'll be recommending Trans Power and using them again in the future as they were highly professional and helped me out of a very difficult situation.