Possible Failed Tube - AGAIN

Ok, I’m stumped. I’ve been fighting this all day and have decided that either a tube that I replaced in October has failed or it is power supply.

I doubt power supply as the current on my test run was 20 MA at 60% power and power supply voltage was 14.6 KV

History: I had a tube burn out in October from what I am sure was overheating. I purchased the new tube and a high quality chiller and have never run with water temperature above 25 and current above 70%. 70% is 22 MA.

All been working well until the last few days. Checked mirrors, all clean and shiny. Checked lens, all clean. Checked alignment, everything right on center. Did a test run with the following number:

60% power

Speed: 20 mm/sec

Power supply voltage: 14.6 KV

Current: 20.0 MA

Water Temp: 21 C

Beam color: Looks good, Pink


Will barely make a mark on plywood

Tube details:

Cloudray RECI

Model Parameter: W1

Power: 75W -90W

Length: 1080mm

Diameter: 80mm

Recommended current 22mA

Purchased October 19, 2023

Anybody got any ideas other than buying another new tube?

I’m not affiliated with Cloudray… so this is my opinion.

Check the tube at M1 to see if it’s in TEM00 resonance or mode.

  1. properly operating tube
  2. clean and aligned optics
  3. proper focus

If you have these three, they work…

Do you have a voltmeter on your lps? Most people do not, so I’m wondering how you know it’s 14.6kV?

If you speed is <= start speed in the Ruida, it will only deliver minimum layer power. Many are set to 20mm/s … suggest you check it.

Good luck



The Cloudray power supply has Control Voltage and Output Voltage display. I also have both digital and analog mA (see photo)

As I said, I changed out the tube with a new 60 watt that I keep as a backup spare. All alignment is good, checked all the way from the tube to the nozzle. When I tried to use the new tube, it produced a very nice line but not enough power to cut 3 mm plywood with multiple passes. That is when I noticed the Output power was 14.7 KV. Speed was set to 20 mm/sec. 60% max power produces the working current of 20 mA for this tube. The minimum was set to 50%. These are settings I have used for some time to cut 3 mm and it has always performed well.

This machine has been producing some great work until now and my diagnosis is a bad power supply. The 75 watt tube may also be bad because of the ghost spot that I was getting (not getting that now with the new 60 watt tube) but I will determine that when I have a new power supply. I also have a new 75 watt tube on order.

Takes a long time for anything to get to me here in Guatemala, that’s why I try to keep lots of spares. Just did not have a spare power supply and that failure caught me by surprise. That will be duplicated.

I am not a newbie at this. I am an electrical engineer and our business is yacht electrical systems. I built this machine from the ground up.

Thanks for your comments and assistance.

Captain John M. Brandes, AMS
On Behalf of Erwin Rivera

Erwin’s Yacht Service
Aldea Rio Dulce, Livingston
Izabal, Guatemala

Office Phone: +502 5732 0219 (English)
Cell & whatsapp: +502 3319 6939 (Spanish)
Erwin’s Yacht Service | Captain Johns Marina (riodulcemarina.com)