Omega D6 with Ilfospeed Multigrade 400 HL

[MattKing]

If it changed the intensity it would change the exposure times!

That is how the speed matching built into the controller's "program" works.
Unlike a colour/variable contrast head with movable dichroic filters, the 400 head has two fixed filters - one yellow, and one magenta. It achieves contrast variation by varying the mix of magenta filtered (green) light and yellow filtered (blue) light.

 

[Sika]

FWIW, I was wrong in one part of my earlier posts - the D6 I had was the older, grey version with a double column, rather than the last version with the single black column.
Here is the operating manual for the MG400: https://www.ilfordphoto.com/wp/wp-content/uploads/2017/06/MG400_Operating-Manual.pdf
And here are the wiring diagrams:

Matt, by any chance, would you have the head schematics ?
Thanks in advance.