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Old Oct 16, 2009, 02:11 AM
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Originally Posted by jj604
Just watch the safety issue. I posted some stuff on this earlier in reply to Charles (Everydayflyer). It DOES work but you have to remember:

1) The cases of these supplies and the -ve rail are normally connected together and are connected to ground (and thus with 2 in series to work, one case is connected to the charger input -ve and the other is floating) so you must make sure they don't touch if you use them in series. Otherwise: very high current dead short across one supply.
2) Because you can't use a 3 pin mains ground connection on both supplies (otherwise you have a short through the earth/ground pin), there is a POSSIBILITY that one case can become live at 110/240V if there is a failure in the supply and hence mains live potential appear on the (now unearthed) case - small probability but hey it's your life.

It IS possible to safely connect two of these in series but you need to fully insulate them.

Your call.

Regards, John
Yes you are a real expert.

I do notice this before getting started. I open the adaptors' cases and reconnected one of the neg outputs, that is, desolder the Ground wire from the board(which connects Main power GND and Neg output), insert a 1uF50V capacitor and solder the wire to the capacitor. This makes the neg out DC floating. This one is the upper unit of the two, the other one's output stage was left unchanged. Drill a hole to let the series connecting wire go through. Mount a red banana outlet on the upper one and a black on the lower one.

Then I removed one of the power inlet sockets and connect the input to the other socket, all 3 input wires L, N and G are soldered together using teflon wires and shrink tube, that required to drill three more holes on both cases. Now I got the two adaptors stacked and double-sided taped. A 430W power supply was done, reliably.

The beauty of this DIYed thing is it's so quite, no fan to disturb my sleeping daugher (the 0720 is noisy though ).
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