15-12-2016, 10:06 AM
I would expect the ±12V rails to be lightly loaded in comparison with the +5V supply and it is probably the current drawn by this that dictates that both secondaries in parallel are required to source it.
I find you earthing comment puzzling, Andy, as the drawing clearly shows the chassis as being the negative side of the +5V and +12V rails as normal. It is, of course, also the positive side of the -12V supply, as you would expect.
We can't see the entire circuit so, if the metalwork is bonded to one of the positive rails - which one? You don't say - at some point, all those earth symbols are very misleading!
I find you earthing comment puzzling, Andy, as the drawing clearly shows the chassis as being the negative side of the +5V and +12V rails as normal. It is, of course, also the positive side of the -12V supply, as you would expect.
We can't see the entire circuit so, if the metalwork is bonded to one of the positive rails - which one? You don't say - at some point, all those earth symbols are very misleading!
