Current dropping off, end of life RECI tube, how best to manage.

[john banks]

We have a 2012 Shenhui 1280 with Reci V4 100W.

I hardly ever need to fix it and my wife runs it. It doesn't run full time but must have lots of hours on it so far, will see if there is a menu to bring it up. Amazed the tube has lasted this long.

She has noticed that the cutting performance has dropped off so that something she might cut at 20mm/s maybe needs 16mm/s.

The ammeter is showing only 22mA and was 26mA originally. I have checked all the connections and they are good.

I changed the max power on the controller from 90 to 95% and it now runs just over 24mA and I will hear about the related performance.

Question is whether I get the spare tube out that has been stored since 2012. This was the original tube that came in the machine, I swapped them after about a month to check something and then put it in the cupboard. So it did work.

Is gas loss (which this presumably is due to the current drop, unless the PSU is going off) equal for a glass tube in use or in storage all other things being equal? Or is it related to use?

I improved the earths on the machine when we got it, but don't really want the downtime or potential explosion if the tube fails suddenly. Is it more likely to just gradually lose power?

[Kev Williams]

What's the water temperature? I don't have an actual chiller for my 80w RECI, just a 'cooler' I've always noticed as water temp goes up, the meter starts reading lower mA and cutting ability decreases. The difference between 21c and 24c water temp is quite noticeable...

[john banks]

Ages since I setup the CW5000 but I changed it from being linked to ambient and I think it is 16C all year round.

[John Noell]

I have not heard anything positive about tubes stored for years so please let us all know if that stored tube works for you.

In my limited experience, a dying tube just slowly fades. I don't think there is any way for the tube to do anything more dramatic.

[Matt McCoy]

After four years, probably time for a new tube. No penalty but effort and hours in goosing the usual checklist before resigning to a new tube or PS, so why not give that a go.The Conventional wisdom is that stored DC tubes off-gas and don't have a long shelf life.

[john banks]

Changed the tube to the stored one and it was slightly better. Tried the other power supply and better still but 24 hours later there was sound "like a filament in a light bulb blowing" and the laser power was lost. When I got back and investigated the laser power supply fuse was blown. Replacing it produced a loud pop from the power supply. Back to the original power supply and all seems reasonable enough with 24mA at 90% power and decent cutting speed. Will see how it goes. Perhaps a capacitor blew on the power supply, will strip it and check.