First, I'm extremely inexperienced in hydraulic repairs beyond rebuilding rams. I have a Hurricane Ian issue. I have a Komatsu PC228 on my barge and during the storm, It broke loose and went partially over the side. I've recovered it and the engine has been brought fully back to life. No water entered the tanks, cab or the compartment with the electric solenoids and valving. The machine crawls and swings. The arm and bucket work. The boom will only go down and not up, which is my question. In the course of recovery, the boom was tugged on which resulted in it being pulled down from it's raised position in a non running state. When the machine is running, the boom will lower without any noticeable load on the hydraulics and when trying to lift, no nothing. Where should I start my troubleshooting? I need to get the machine going enough to pull my anchoring spuds so I can get to the beach and drive it off for whatever else lays ahead.
There are a multitude of pc228 over the generations. On my PC228UU-1 (and my PC128UU-2), it has a cab protection system that prevents boom rise, and stick in, to prevent cab/ bucket interference, that can be overridden by holding up the momentary toggle switch under the seat cushion, below your right leg when seated. Holding that toggle in the up position disables the cab protection system, and will allow boom rise, in the event of sensor(s) failure. Does your machine have a sensor at the boom base, visible though the cab window? If so, start there.
I have a PC223US-3, so it's not exceptionally modern. There is supposed to be a boom angle potentiometer according to the shop manual but I haven't found that yet. I will check for that toggle somewhere.
The potentiometer is on one side or the other of the main boom pin. On mine, they are on cab side. Looking on web, some are on opposite site, in compartment. When any of the potentiometers are open or shorted, the boom will not rise, until the system override is held on.
After your idea about the cab protection system, I have started looking in that direction. I hope I'm on to something. Thanks