Monroematic problems

[belgian]

I have been lurking for quite some time on this nice forum, and decided finally to join following a real technical issue I experienced on my Kubota Bulltra B1-15.

This tractor is equipped with the infamous electronic hitch control Monroematic, and gave me fits recently since the hitch suddenly decided to quit on me. The balancing piston on the right side still functions with the Monroematic, but the normal lifting on the hitch doesn't work anymore. I can lift the arms by hand, but they don't move an inch upwards.

The dealer I purchased the tractor from doesn't have a clue either how the system works, and I couldn" find any info about the wiring systems so far.

So, being stuck with this problem, I was wondering if anyone had some info or knowledge about the system and its components.


here's the control panel




The balancing piston at the rear



the hydraulic hoses and valve that feed the balancing piston



there' a little sensor or potentiometer fitted to the left lifting arm. What is the function of this item ?




Below the seat is this magic black box. What is its function ?



and this is the hitch main control handle (note the wiring mess)




I know this is a bit much to ask as a newbee, but if you folks could give me a some clues about the cause of the problem and some advice would really be appreciated.

looking forward to your comments. Thanks

 

[lsmurphy]

Could be the sensor, or the panel, or the solenoids at the valve. Have you go anyway to check for electrical current? Has it got power?
In your last pic you have two solenoids that actuate the valve that controls the fluid flow either to the lift arms or to the tilt cylinder........test for current when you manipulate the panel......if you have current but no action it will the solenoid that is bad......if you have no current trace it back to something else.

Does the panel have in internal fuse? have you checked the fuses?

 

[belgian]

Could be the sensor, or the panel, or the solenoids at the valve. Have you go anyway to check for electrical current? Has it got power?
In your last pic you have two solenoids that actuate the valve that controls the fluid flow either to the lift arms or to the tilt cylinder........test for current when you manipulate the panel......if you have current but no action it will the solenoid that is bad......if you have no current trace it back to something else.

Does the panel have in internal fuse? have you checked the fuses?

Thanks for your reply.

1. I checked both solenoids and they get power, but no action. What I didn't quite understand that they got power both at the same time. Is this normal ? How can you check if the solenoid is bad ? Is there a specific Ohm value to look for , or is there a firm movement you can hear when actuated ?

2. the tractor has 2 fuses in the front (15A and 30A) but both are still ok. I don't know if there's a fuse in the panel, think I will dismantle the panel later today or tomorrow.



I'll

 

[belgian]

I did dismantle the control panel today and found that the electronics are completely sealed and not fused. I doubt the board is defective since the balancing piston control is still working. Not much we can do here anyway




Checked both solenoids on the main valves and they are still operating. You can hear them work when powering them.

My suspect is finally the potentiometer hooked to the hitch control handle.
Measured the resistance and no value when rotating the handle.

here it is.




I have been thinking of getting rid of the whole electronic system and just mounting a dip switch to control the valves directly. anyone done this before ?





does anyone know if this can be purchased as Original part ? It does 5kOhm but it has a particular mounting notch that won't be easy to find a replacement.
I have been thinking of dumping the whole control system and use a switch to control the valves directly. anyone have done this before ?

 

[lsmurphy]

I have no experience with it personally, just using common sense as you are. That pot cannot be all that expensive.........maybe try to replace that first?



Should be a common part at any electronic store............don't guess you have a Radio Shack in Belgium? .......LOL

 

[helomech]

Just because you have power on a meter does not mean it will work. You can have voltage, but no amps. Test all your hot wires with a light bulb, if it will light up the light bulb the power is good. Had my ass kicked on many helicopters because of this. Meters are not great for trouble shooting IMO

 

[lsmurphy]

http://www.tractorbynet.com/forums/...38-monroematic-auto-3-point-controller-3.html


http://www.orangetractortalks.com/forums/showthread.php?t=464

 

[belgian]

Well, I checked all potentiometers thoroughly by an electrician at work and all seem to work properly.

1. potentiometer of handle position
2. Potentiometer of hitch position

I also get power on the hydraulic valve solenoids when testing the system, so I am now back to where I started.

Now my focus is on the hydraulic system, inlcuding the valves.

There should be oil pressure since the balancing piston (controlled by the shifting valve located on top) is working.

I hope you guys can give me a procedure about the hydraulic system and how to check it. Now where do I start ...

 

[lsmurphy]

Well, I checked all potentiometers thoroughly by an electrician at work and all seem to work properly.

1. potentiometer of handle position
2. Potentiometer of hitch position

I also get power on the hydraulic valve solenoids when testing the system, so I am now back to where I started.

Now my focus is on the hydraulic system, inlcuding the valves.

There should be oil pressure since the balancing piston (controlled to the shifting valve located on top) is working.

I hope you guys can give me a procedure about the hydraulic system and how to check it. Now where do I start ...

Read the discussions I linked to above........what I got out of it was that the tiller needed to be plugged into the system.

See if you come to the same conclusion.

 

[belgian]

Read the discussions I linked to above........what I got out of it was that the tiller needed to be plugged into the system.

See if you come to the same conclusion.

Lsmurphy, I read through that discussion before starting this thread, I have been researching quite a bit.

I understood that the swing sensors located on the the Original tiller were used for automatic depth control controlled by the monroematic. If you remove the tiller, you don't have the automatic depth control any longer, but that does not prevent you from operating the balancing piston manually on the panel, nor does it prevent you from operating the hitch normally with the handle.

Please note that the tractor has been working fine during a few weeks before I suddenly couldn't lift the hitch any longer (and that was without the famous tiller which was originally used in Japan)

I think i must have a valve problem somewhere.

 

[olthumpa]

Just a thought. This is the short version.
I had a motorcycle that would not start with the key. There was power going to the solenoid. Using an old battery cable I jumped the solenoid and the motorcycle started. I replaced the solenoid and my problem was solved. I then tore apart the old one and found that the high amperage contacts were burnt out.

Is it possible to remove the solenoid, disconnect the hydraulic lines and see if compressed air will be allowed to either pass through or not pass through the solenoid when it is activated.
(I do not know it is supposed to be open or closed when power is applied)

Just my two cents worth - GOOD luck

 

[belgian]

Here's some update on the situation.

I dismantled the valves today and checked the solenoids again to see if they really operated. And they did. Checked with air pressure as suggested, all working.

So :
Monroematic ; OK
valves and solenoids : OK
main oil pump : OK (balancing piston works with high pressure)
Oil level and Oil filter : OK, clean as a whistle


So the only item remaining is the main piston for the hitch inside the main frame I guess. Anyone experienced a sudden failure of that piston ? This problem really has me stumped. Come on guys.....

 

[belgian]

Final update : the hitch is runnin ...!!!!!

I decided finally to dismantle the valve block and the block located on top of the hitch piston.

I opened the valve block and found that one tiny spring loaded valve was a bit sticky. After cleaning and polishing and reassembly, the hitch finally was working again.

Put a lot of work and patience in this one to get the problem solved, and am still a worried that this problem may reoccur.

I think I deserve an icy cold belgian style beer today.

 

[Noto]

I know its a long shot to boost a topic thats years old. but im kinda desperate to get my hitch up and running again.
The valve you cleaned is that the black magic box from the first post?
Or maybe anyone else can tell me what he did so i can try that as well.