View Full Version : More problems, Shenhui Laser

Brent Ramsay-Boyd
08-20-2014, 7:28 AM
I have had a shenhui laser for about 7 months now, and have battled with it from the get go.

I finally narrowed down the problem to the tube, and have been sent a new one which will arrive in the next few days, hopefully intact.

I had a spare tube, which after making sure I covered all my bases with regards to voltage regulation, making sure there were no bubbles in the tube etc,I got the machine back up and running on Monday. I ran the machine for about 30 minutes, with no issues, happy that it was back up running as it should.

This morning I came to cut again, I started everything up, checked to make sure the tube was free of any bubbles, lined up the laser and pulsed the laser to check my focus was right and what I think was the tube, made a sharp hissing sound, louder and different to the sound of the laser firing. I pulsedthe laser once more, and it made the same sound. I then turned off the machine, checked everything was connected properly, and it was, water was flowing, air was flowing, everything was as it was when I ran it on Monday, the machine had not been touched since then, am I am the only one with access to the room, so nobody else could have been in there.

I turned the machine back on, and tried to pulse the laser again, and this time nothing. The tube is not firing at all. As it was cutting fine the last time, I cannot figure out what might be wrong. All I hope is that the tube is not destroyed, but I am not optomistic.

Anybody, had a similar problem. This was supposed to be my opportunity to have my own business, but it has been nothing but hassles since the get go and I am running low on patience.



Matt McCoy
08-20-2014, 10:13 AM
Have you checked your power supply?

walter hofmann
08-20-2014, 10:28 AM
check your tube connection wires and if you got a big green resistor check them too and also the black or blue wire which comes from the tube then goes to the amp meter.
the hissing sound is mostly coming from a jumping spark.

Mike Null
08-20-2014, 10:51 AM

Did you read the Shenhui thread started by Rodney Gold. It has an encyclopedia of info and may hold your answer.

Brent Ramsay-Boyd
08-21-2014, 6:18 AM
I have read through the shenhui thread, and cannot find anything. I tried again this morning, when I pulse the laser I get a very small hissing sound from the tube, like it sounds when it is firing, but nothing is showing on the ammeter, and there is no sign of life in the tube.

My next step is to replace the power supply, but I am weary, as I am worried that there is something I have done that may be causing the issue, and I do not want to blow a tube, or power supply, as it can get very costly.

I have recently added a voltage regulator to the machine, but I cannot see that this would be the cause of the problem.

Bill George
08-21-2014, 8:06 AM
Are you sure its from the Tube not a high voltage wire shorting somewhere. Carefully remove the cover for the tube and make sure you can see the HV wire all the way back to the power supply. Darken the room and have someone press the button while you watch. Could be HV arcing to ground somewhere. I have never heard my tube hissing when fired, but I am hard of hearing....

Brent Ramsay-Boyd
08-22-2014, 6:03 AM
The tube only hissed twice. Now the tube is not firing at all. I have had a technician come and look at the machine. There is no sparking anywhere, we have swapped power supplies and still not even a glimpse of life in the tube. There is a very slight sound of it trying to fire and that is about it.

The only thing we can think of is that the tube has sprung a leak, and the hissing was the tube forcing out the last of the gases as it pulsed. There are no visible cracks on the tube, but I did find a small piece of the epoxy sealant in the machine directly below the tube. My only guess is that the gases have leak from there. My follow up question would be, is there anything that would cause a tube to leak like this (ie something I could have done wrong), Or is it likely just down to a flaw in the tube?