Hi,
  I'm trying to tweak the resistor values in an intensity/focus chain for a
CRT. The circuit ATM looks like this ('scuse the ascii art):

             47k     20k          82k     100k      940k (2x470k)
-600V <<<---/\/\/---/\/\/---*----/\/\/---/\/\/------/\/\/-----> 0V
              ^             |              ^
              |             |              |
              |             |              |
              |             |              |
          Vg1 (inten)   Vk (cathode)   Vg3 (focus)
          
Now, this looks to me like two potential dividers, which combine to make one
potential divider and two "sub-dividers" if that makes any sense. If I change
the total resistance on one side, the other side will be affected and vice
versa. So how do I pick resistor values for this thing?
          
Here's how I simplified/understood it:

            67k           1122k
-600V <<<---/\/\/----*----/\/\/-----> 0V
                     |
                     |
                    Vk

At the moment, this circuit's outputs are (assuming my maths is correct):
  Vg1: -600V to -574V
  Vk:  -564V fixed
  Vg3: -522V to -492V
  
What I need is:
  Vg1: -600V to -550V
  Vk:  -500V fixed
  Vg3: -500V to -380V
  
So how should I go about modifying this circuit? So far this is the best way
I've come up with:

1- Work out the values for the simplified circuit, so that Vk = -500V for
   R1+R2=1Meg2. New R1=x, new R2=y.
2- Split the circuit down into two dividers.
3- Calculate the component values required for the Vg1 divider, with R1+R2=x
4- Calculate the component values required for the Vg3 divider, with R1+R2=y

Does this sound like it'll work?

Thanks,
-- 
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