Problem with Iwata Neo

[macsporran]

Anyone here expert on troubleshooting a Neo CN?

This one is doing my head in. Mt Neo CN used to work perfectly but now will not supply air to the nozzle.
I recall last using it successfully then stripping down to clean as usual by extracting needle etc then re-assembling. I have been using other brushes for a few weeks but when I try to use Neo again I get no air through it!

Specifically the brush is attached to compressor hose via a water trap at the Neo's air valve body and when I depress trigger nothing happens. There is full pressure at the trap (it has a release valve to check) so full pressure is entering the Neo air valve, but not beyond it. The air valve on inspection appears fine with spring, rod and O rings in place and, when I push trigger down I can feel the spring resistance in the air valve, but as I depress trigger against spring, where I expect to feel airflow, nothing happens.
Apparently something must be wrong with the air valve, but I cannot see what.
Any thoughts?
Help?

Thanks, Sandy

[pepperman42]

Don't own one but sounds like the pin in part N-020-1 isn't lined up with the the trigger so when you push down for air it's either passing the pin or the pin jammed. I'm looking at the parts diagram. Is the little red seal N-150-2 there?

Steve

[macsporran]

Thanks Steve - the pin is moving when I depress the trigger. When I look at the unattached airbrush from below I can see the piston pin moving towards me as I actuate the trigger against the spring.
It's got me beat. I can only assume some blockage in the valve such that even when the pin goes down air cannot pass - but I can't see where it's occurring.
I have never dis-assembled the air valve itself so I don't see how it could have become internally mis-aligned, but this is the only thing I can think of. I don't think I have the right tools to get into the air valve anyway.

The only parts diagrams I have just show the whole air valve as item 15. Do you have a detailed exploded diagram of this you could post - that might help.
Thanks for any and all help
Sandy

[kensar]

Are you sure the blockage is in the air valve and not 'downstream' of it?
A possible test would be to connect the air valve alone to a low pressure air source and press down on the pin?

Just offering an idea.

[macsporran]

Excellent thought, Ken, thanks I'll give that a try.
(Certainly air hose, trap, etc is fine as it works perfectly with other airbrushes.)
Sandy

[macsporran]

Tried attaching only the air valve as Ken suggested - and this works perfectly: depressing the piston rod gives a satisfying blast of air.
But, when reattached to Neo the trigger does not produce same effect. I can feel the resistance of the air valve spring, so it is engaging, which presumably means air can leave the hose - but is not doing so. The air valve chamber must be blocked then? I have never dis-assembled this part so cannot see how it might have changed.

I need to investigate that chamber more fully - but it probably needs rather a specialized tool to unscrew the internal brass widget. hmmm.
Sandy

[macsporran]

Hah! Problem solved.

This really arose from me not thinking about how an airbrush works. I had assumed the air from the hose/valve mixed with the paint in the body of the tool. (I am ashamed to say I have a degree in Physics (from way way back) so I should really have known better!)

This is simple stuff but it caught me out so maybe worth repeating here in case anybody else has had problems.

The air from the hose enters the air valve and occupies a chamber in which is a piston connected to the bottom of the trigger. Depressing trigger allows air from the hose into the chamber and, I had assumed, up into the brush - but no, entry to the brush is still airtight.
Instead there is a fine conduit from the valve chamber to the nozzle, opening into the nozzle chamber interface with the needle/cone assembly. Presumably the Bernoulli effect of the air passing through this chamber lowers pressure and fires the paint mixture through the nozzle.

This conduit was blocked in my Neo and careful cleaning with wire brush and solvent allowed the pressurized air to pass again, producing a stream of paint once more.

I've been airbrushing for thirty-odd years but this has never happened to me before: you live and learn. In future I will clean out this little tunnel in all my airbrushes when I clean the needle pipe.
Stupid me.
Hopefully though, may help somebody else in future.
Sandy

[kensar]

Glad to hear you got that sorted out.  I've never heard of that problem before either.  First time for everything.

[pepperman42]

Glad you resolved it.

Steve

[WD]

Good to hear this Sandy, glad it's all sorted out now.

Warren