Originally Posted by
notreallyy
Basically, what happened is this: the chain was scratching the inside part of the cage (on the highest crown) so I tryed to use the H screw but it didn't do anything; at some point while trying to make it works (I don't remember how) the derailleur and the chain got stucked so I had to remove the derailleur from the frame (the screw still weren't working).
While remounting it, adjusting the low crown with the L screw, it didn't do anything because as you can see the screw stops when it touch the pantograph: (the cable is not set yet)
http://oi57.tinypic.com/ao10y.jpg
For pantograph I mean that thing on which the L and H screws operate to move the cage (in the picture above is the black thing under the screw)
Is the screw actually bottoming out? I.E. is it too short? That would be very, very unlikely. Presuming it's not, the H and L screws ideally need to be adjusted when they're not under any tension, which means you may need to use your hand to back the cage off so that you can get enough travel distance on the screw to get it adjusted correctly.