Le Maitre Neutron PRO (Star) hazer gubbins

[Nicktaylor]

I have couple of these. The main issue is the feed pipe getting clogged I think. They actually became too unreliable for hire stock, I am a little hire business so resource backup is not really there. I suspect over time, and I bought them second hand they have not been cleaned after use so have just got bunged up. In my case the other issue is they are a little different in age so warm up times are different anyway. I know just sub in from a friend who has a couple of Showtec units which cost relative peanuts and do a satisfactory job for shows the Neutron would be used for. However as others have said we all have time on our hands so maybe I should try and refurb them!

[bigclive]

From the smell of the liquid I think most of the short-heater and air pump style hazers work with glycerol based liquid. Between the use of glycerol and occasional inadvertent use of oil based haze fluid by well meaning crew it does mean that the heater pipes should be considered a disposable item.

 

I've never really had a chance to explore a neutron hazer. Is it the type that uses the pipe itself as a heater by passing high current at low voltage through it?

 

If it is, then theoretically the ultimate service for these units would be to replace the tube with a new one if it was clogged and make sure the electrical connections onto the pipe were clean and solid, as any resistance at all would impact the current flow and heating ability greatly. The pipe would also have to be the correct gauge and material for optimum results.

 

The liquid and air pump are also cheap and disposable items in my book.

[KevinE]

yes, directly heated. The later ones use a straight tube around 4 or 5 inches long and a small rodding drill is stowed inside the cover for convenience.

These have a strict controlled shut down like the Unique if blockages or spitting is to be avoided. There's also controlled start-up which is supposed to gently heat and eject any stray fluid before entering normal running mode. I suppose it's designed to prevent burning and coagulation.

 

Of course this is all academic when the thing is installed under some stage and turned on and off by switching the mains socket in the DJ box.

[bigclive]

I can guess that the shutdown is simply stopping the fluid pump and keeping the air one running for a while to try and get any residual fluid through.

 

These things never get shutdown properly in an event environment.

 

Are the pipes in the direct heating system made of stainless steel?

[J Pearce]

The pipe is quite malleable, so I'd guess copper or brass. As far as I can work out the shutdown just clears the pipes as you suggest.

[bigclive]

Brass and copper are quite conductive, so it must be relying on very high current at low voltage for such a short length. That makes even a slightly oxidised connection an issue.

 

What would you guess is the rough diameter of the tube?

[J Pearce]

Going from memory 4-6mm, not particularly thick wall either. There’s a coil of wire at the end involved too, which can sometimes gets as far as glowing red (usually at startup). I wonder if the outside of the tube is one conductor the other feeds off an internal wire/bushing - been too long since I had one apart to remember.

[Brian]

The Neutrom XS manual sayas that the tube is Stainless Steel.

[J Pearce]

I stand corrected. Thanks Brian :)

[Brian]

The manual is on the LM website and has a description of how it works.

[KevinE]

here's an excerpt from the manual describing 'autocleanse'. Certainly the XS versions go through this at shut down as well.

 

Circuit Action -

At switch on, initial readings will be taken and the circuit allowed to settle.

A cleaning phase will always be entered. This involves the air pump, the fan, and

current control to the tube. The tube will be taken to a much higher temperature than the

normal running temperature.

The air fan will pulse, and a reduced current flow will be issued to the tubing. At

around 300C the main fan will stop, whilst current flow will continue. At a higher

temperature level, current flow will cease, and the tube allowed to cool. Again at

around 300C the fan will start pulsing, to cool the tube. The current will be re-applied at a lower temperature, and the process repeated several times until, finally, the fan will be

lower temperature, and the process repeated several times until, finally, the fan will be

switched to full flow, the temperature switch points changed to normal operation and the

main routine entered.

This is a simple heat up -cool down -fluid pump -heat up -cool down etc.

Software fail sensing is continuous and is present in both cleaning and operational

modes.

Edited May 12, 2020 by KevinE

[bigclive]

The stainless steel makes sense as it has a relatively high resistance and makes direct heating more practical. That also applies to the thinner wall size.

 

The cleaning cycle suggests that it might be trying to dry out, dislodge and then blow out any residue as dust. It suggests it might pay for a hired unit to be run through several cleaning cycles occasionally, to try and compensate for the complete lack of proper shutdown that usually happens on a hire. Clever that they do one at startup to guarantee a self cleaning cycle.

[KevinE]

certainly more clever than the unique, maybe why they have a slight reputation for being temperamental.

For example the heater triac going short will not lead to overheating, just a flash code. I saw a unique overheat such that the glass wool insulation became incandescent. This was due to a bodged repair where the thermocouple had been connected backwards.

 

The fluid pump is also short protected so it can't continuously pump under fault conditions. The punp has an undersized supply fuse, and the triac keeps the current lower than the rupture current. If the triac goes short, the fuse blows and it fails safe.

 

The tube heating current is 30A.

[bigclive]

I wonder what voltage drop there is across the tube. 30A is lower than I expected.

[KevinE]

I've just measured an XS 'straight' tube and its 2.3mm OD. Very thin wall. The manual recommends deep cleaning with dilute hydrogen peroxide. I dont have a curly one to check.