Is my tube dead

[avalonman]

Can anyone answer the following.

Ive been loosing power for ages and have checked the alignment which seems to be OK over most of the work surface, I then decided to cover the mirror that is closest to the tube and this is what i saw.

When the beam hit the paper it created an arc shape like a cresent moon and not a full filled circle as was expected

I then held down the laser button for a count of 5 and no burn at all on a fresh sheet of paper.

I then sent a piece of work through the system and it did partially engrave at slow speeds but not fast.

anyone any clues

[Spooky]

It does sound like it's on it's way out ,to be honest though I would call HPC and ask Chris as there can be other reasons for what you describe and you don't want to be buying a £300 tube if it's not knackered

best wishes

Dave

[avalonman]

Thanks for that.

fortunately I have a spare tube i bought when i got the machine so if it is dead then it will just be a swapout and setup job. HAHA i bet its not that simple

[Spooky]

Tube swapouts are usualy pretty problem free, just ensure you don't over ighten the clamp screws or you can warp the tube or crack it

usual method,leave the machine off for 12 hours before removing the red wire (or even touching it)

best wishes

Dave

[tweakie]

Just a though but I have read about a crescent shaped beam before, on another forum. They found that cleaning the output-coupler (lens / mirror or whatever you call it) recessed within the water jacket at the business end of the tube cured the problem. They didn't say just how they cleaned it because there is a more than good chance that anything touching at that point will be burned-on. Worth a try perhaps ??

Tweakie.

[Spooky]

As usual a very valid point from Tweaks the 6840 tube isn't enclosed very well so dust and dirt can get to the coupler, I remember having the same issues on my 6840 come to think of it

best wishes

Dave

[avalonman]

Ok

I took you advise spooky and talked with Chris about the tube and went ahead with a swapout.

i started at 10 am and was up and running again at 1:30pm, wow what a difference.

After the job was completed i decided to look at the old tube and as was suggested the end was thick with smoke residue, I have managed to clean the mirrored section with good old baby wipes and cotton buds and have put it on one side just in case it wasnt faulty but just filthy.

By the way is there a way of testing tubes outside of the machine ?

[Spooky]

I don't know of one(electronics isn't something I'm good with) but a good clean up and keep the tube as a spare is a good idea. Dirt and muck cause quite a few problems especially if they are on the coupler end.

The 6840 is a bit of a bugger for that as the tube isn't fully enclosed like it is on the 1200 series.

Tube swap outs aren't usually too bad a job, main thing is DON'T move the actual tube mount unless you REALLY must, it can make realigning a pain in the butt

best wishes

Dave

[avalonman]

One idea ive had whilst changine the tube was to enclose the tube compartment by fixing some clear acrylic to the metal panel that supports the light.

that way i know only a small hole would be made by the laser when first installed it would help keep the smoke off the laser and first mirror and with a simple wipe down when doing the weekly cleanup i would maintain a visible inspection on the tube.

by the way does water flow through the coiled glass tube inside as i cant see bubbles in it?

[tweakie]

by the way does water flow through the coiled glass tube inside as i cant see bubbles in it?

Water does not flow through the coiled glass tube. If you can see bubbles in it then lets hope they are bubbles in the glass.

Tweakie.