Hardi sprayer control valve

Farmer mk1

Member
Arable Farmer
Location
Sheffield
Hello.

Has anyone had any problems with the section control valves on the LY sprayer. It's only a 12m but 2 of the sections have stopped working. They work but once turned off they won't turn on again. The main shut off for the full machine works but not the sections. The nsts man said that it might be them switches but just wondering if anyone else had seen this problem before and found a cheap way of repairing it. I've seen the full unit for £280 but considering the machine needs 2 of these and when you take the cover off these units there is only 3 small electrical parts I thought it was abit too expensive for what it costs.
Anyone any clues or known fixes? Thanks
 

Farmer mk1

Member
Arable Farmer
Location
Sheffield
@quattro can these be swapped. I think 2 sections turn off but not on. And the pressure increase/decrease won't work at all? Any idea on this? Any ideas where you can get these micro switches from?
 

Dave W

Member
Location
chesterfield
Pop the black plastic front off the valve. As said there are 2 micro switches and it will almost certainty be the plunger stuck in in one.
You should be able to flick it out with a screwdriver and get some wd40 in. I’ve had loads like that and never had one that couldn’t get going
 

deere66

Member
Location
York
The junction box on the sprayer has a circuit board to split the wires off to the separate valves, this can fail over time. Just re wire with a block connector(y)
 

Bramble

Member
Could also be the cable between the control box and the micro switches. Check it for any signs of breaks/rubbing. Could check the continuity of the cabling or swap one of the ones that works for one that doesn't.

Most likely to be a fuse or stuck micro switch/plunger though.
 

deere66

Member
Location
York
Is it easy to see how the circuit board is wired to rewire it with block connectors?
Image0410.jpg

Very easy to see.
 

Mursal

Member
So you have no power to turn them ON?
But have power to turn them back off

Can you disconnect the working section and connect the wires to each dud valve in turn to see if the valve works?
That might narrow it down a bit for you. If it doesn't work with good wiring its the valve. If it starts to work, its the wiring / switch. Can you take a picture with the cover off the two dud valves, please.
Strange that the two went down together they might have a common earth.
 

Dave W

Member
Location
chesterfield
The system doesn’t actually work on/off. There are 2 wires to a motor. The switch is a double pole double throw setup. It effectively turns pos to neg and vice versa.
The motor in the valve turns until the cam triggers the switch and cuts the power supply. Switch power the opposite way and the same happens in opposite direction.

If it’s working in 1 direction then it’s not a wiring problem (other than possibly the switch)

I always think it’s worth turning the valves manually to the mid point with power off when parking up for winter. That way both plungers in the switches will be out.
 

David.

Member
Mixed Farmer
Location
J11 M40
It is likely to be one of the micro-switches that the cam contacts with.
It is also worth really properly cleaning the contacts in the plug and socket to the control box.
 
Last edited:

e3120

Member
Mixed Farmer
Location
Northumberland
The way those diodes are arranged will mean that the switches are only in play when the current flows 'up' them. So the LH switch is only needed when the LH input is live and vice versa with the right. If you try to open the valve and then check which side is live, you'll know which switch to doubt. Then bypass it and try again. If this works, it won't stop so go steady so as to not drop off the end of that cam.

Alternatively, and this might make sense with your 'goes once then not 2nd time' observation, a diode could be shot. If this is the case it'll be on the side that isn't live. Again can be shorted, but should only be needed to get it moving, then the switch on that side should close again anyway.
 
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