Errmm ... but by your description you've just described I'm right ...
I think we have an apparent "difference" of opinion due to duct location relative to airflow, but are visualising the correct picture.
You have just confirmed what I suspected Pif was alluding to - namely the starter duct is isolated from it's respective main (L/R) manifold by its respective ENG BLEED valve for the -200's whereas the same duct on the later variants can be "considered" to branch off the respective pneumatic manifold directly. Are we in agreement now?
Pretty please?
Yeah you're right, I remember now - ta - the ISOL valve is tucked away between the packs in the A/C bay. It can be gotten to, but it's a bit of a chore.