Hitachi EX75UR excavator.

[Tractortech]

Now Then..
I seem to have landed an excavator repair job.. It's a Hitachi EX75UR, imported and repainted orange from what I presume to be the purple colour of the Japanese ones. All the labels on the machine are in Japanese except the fuse box lid which is in English.
The dipper arm ram loads the engine to retract, however nothing when you try to extend it. The problem I'm sure is electrical in the 'Marccino control', a kind of auto depth control / guidance system. I've found 4 solenoids under the cab, one of which isn't energised, these have the pilot oil running through from the joystick. We now have a machine with the boom stuck right out and some.ground works to do!!
So, does anyone have any tech publications / info / ideas / experience as to what might be at fault??
I suspect this machine was built in the 1990s. It has the knuckle boom with 3 sensors mounted at the pivot pins..
Thanks in advance
Tt, & co

 

[joe soapy]

We have thae exact same machine, had the same problem with it
spoke to somebody that pointed me to where i could bypass the marconi..
Cant remember what i did , twas several years ago now..sorry i not much help.
the marconi was a clever bit of kit when working.
another clever bit was under the floor, a selector there allowed the controls to work in several different configurations

 

[Tractortech]

Now Then..
Maybe I need to join a construction forum with this one, eh.....

 

[joe soapy]

Now Then..
Maybe I need to join a construction forum with this one, eh.....

Good idea, if you find a source of good info please come back with a link.
we bought ours several years ago as a worn out ex hire machine, had to stick a bit of wire across something
to bypas the electronics, 1 track tensioner is a bit corroded,
only ongoing annoyance is having to grease it and top up the fuel
and off course the big bugbear, it wont quite fit into a standard tipper

 

[Mr Happy]

Try the British Construction Forum. Might help, but it takes a while to get excepted if you want to join.

 

[Mursal]

If you open the extend pipe, will it retract without loading?
If so, look for the dump solenoid on the extend circuit, see have you power when retracting?

 

[Timz79]

Hi Tractor tech. What ended up happening with this machine. I have the same machine and the boom used to stop at vertical instead of laying back. Hitachi adjusted it to go back further and now it get stuck when the boom is at its lowest point. Hitachi removeed most of teh auto marccino system. Shoots out error code 19 now. Sounds electrical Auto Marcinno to me. Did you end up bypassing??

 

[nick...]

Now Then..
Maybe I need to join a construction forum with this one, eh.....

Join www.heavyequipmentforums.com which is USA forum.plenty on there.the guy who runs ceforum does not accept anyone new which is why forum is dying.good luck
Nick...

 

[PAL SPC]

Now Then..
Maybe I need to join a construction forum with this one, eh.....

Evening did you ever get to the bottom of bypassing the system? We have one and we’re having various issues with the system and would like to bypass it TIA