Not sure if I'm following you, p1,p2 & p3 come straight off the pump and go directly to the main control valve. I did loosen the hoses from the bucket cylinder, cranked it up and got fluid poring out of one side like it was under pressure (with out touching any controls) i cut it ok, hooked that line back up to the cylinder, cranked it agin and this time fluid pored out of the other line without touching the controls. I thought that there shouldn't be any fluid moving at all from these lines until I moved the appropriate joy stick.
So I don’t have exactly yours diagram at hand, and I don’t work for Kobelco for 20
years to remember it.
i worked on some mini excavators, and they are similar and different at the same time.
The pumps set ups pretty much the same , but combination of the controls and control valve set ups are different!
This one have trochoidal pump just for the pilot, most of them combining branches flow from two or all three pumps to create pilot.
All 4 of your pumps, including piston ones, are fixed displacement, that’s why all parts of you control valve is open center!
Many of these machines combine flow
from two different parts of control valve to run high flow for auxiliary attachments.
If your P1 and P2 combining the flow for auxiliary, and something is connected wrong or got stuck - it may dump all your flow from both parts of control valve back to tank without building up the pressure.
By auxiliary connections, do you mean the lines at the end of the boom near the bucket for like a thumb?
Yes.