Thread: tool imports

Originally Posted by BobL

We also bought a dual voltage PC monitor back from the US - turn it on screen went all funny colours, spent $50 getting it looked at - nothing. Finally we were told that monitors have to be made specifically for northern and southern hemispheres

This is correct. CRT units use a magnetic sweep system to move the beams across and up/down the screen to trace out the picture. The earths magnetic field affects the sweep magnetics to a degree, and the field in the northern hemisphere is opposite to that in the southern hemisphere.

In a black and white tube, the net effect of relocating the set would be that the entire picture would move diagonally maybe .5mm at most, and would not be noticable.

However with a colour set, there are 3 beams sweeping simultaneously, each one intended to light phosphors of a particular colour on the screen, so that the light produced by the group of 3 phosphors mix to produce the required colour and intensity. Controlling the sweeps so that everything works properly can be difficult in the first place, as the beams have to come from different locations, and the phosphor dots are smaller so that a group (1 of each colour) is approx the same size as a white phosphor dot for a B/W TV of the same screen size.

To aid in ensuring that things match up, each beam has to travel through a mask which blocks the beam at points where it might land on the wrong coloured phosphor. In positioning the mask in the tube during manufacture, the earths magnetic field is taken into account, and the masks are offset accordingly. Use the set at the opposite end of the world to that which it was for and you are in the lap of the gods in regard to colour.

There is usually a degree of adjusment capability designed into the set to cope with whether it might be used near the equator or much further away, but it would not cope with changes as a result of moving from Northern Britain to Southern Australia.

Luckily, flat panel screens like LCDs and plasmas don't have the problem.

I recently bought 4 Dewalt hammer drills (925) model and 4 batteries for $920 including postage from America and a dewalt flash/flood light for $20.

So drill/battery and light cost me $250 each delivered. I've also figured i mite as well spend the extra $$ and buy an Australian charger rather than mess around with step down transformers and i'll still be in front.