Trouble Shooting no Laser Beam

[pete00]

Wondering if I could get your comments about this problem.

Here is description of problem that seems to be repeating.
It’s a RECI 80w tube

After I turn on the laser I do a test fire, that’s ok
Next I run a test engraving.

The job starts to run then after maybe 10 -15 seconds the beam stopped.
The head was moving back and forth, air assist was coming out, and everything seemed ok except no laser beam.

I turned off the machine, and then turned machine back on, reset the display, water pump, exhaust were all running. I tried to do a test burn, no beam.

Turned on machine about a couple of hours later and was able to do test burn, started a job and 10 - 15 seconds into job beam stops.

I went a day of so without being able to test fire with a beam.
Then the next day I get a beam, that stops after 10 15 seconds into job.

Working with manufacture and voltage meter, I check voltage on laser power supply.
Check the voltage on power supply as job was running to make sure controller card was working.
We bypassed the water flow safety connection.

We configured the power supply to fire the laser manually when I touched two wires together.
Everything seemed to pass the tests except no laser beam.

The only thing we haven’t checked is the actually high voltage lead on the tube to see if we have current. Not sure I know how to do this SAFELY.

We’re not sure where the problem may be, tube or power supply.
There’s no issue in getting replacement parts, still under warranty.
I have another tube and power supply on the way, should be here in a week.

I should have order all my spare parts before as planned but I didn’t.
I will be ordering SOON.

Does this sound problem sound familiar to anyone ?
thanks..........pete

[pete00]

Im not sure I would to do this, could be dangerous but.

If my meter can handle the voltage, think it can go to 20,000v

Could we put the test meter on the high voltage lead on the tube to see if we have power there, when the job is running.

If we have power at the connection wouldn’t that mean the tube is bad.
If we have no power at the connection would that mean the power supply is bad.

Or is it not that simple because i don't understand the magic of electricity and the way it works with the tube.

pete

[curious]

Originally Posted by pete00 Im not sure I would to do this, could be dangerous but. If my meter can handle the voltage, think it can go to 20,000v Could we put the test meter on the high voltage lead on the tube to see if we have power there, when the job is running. If we have power at the connection wouldn’t that mean the tube is bad. If we have no power at the connection would that mean the power supply is bad. Or is it not that simple because i don't understand the magic of electricity and the way it works with the tube. pete

maybe !!!! you have problem with your cable ,so in a certain position it is like a broken cable. but if you put it in a other position or later ,or when it cools down its ok again.

just buy at the car shop a high voltage checker, it has a small light in it
you only hold it against the cable and see if the lightbullb is on.
it s the same to test spark plug
but be very carefull ,dont use near tube
only outside red cable near high voltage generator.
better use oscilloscope and measure pulse

[Exsecratio]

The last place on earth you want any part of your body is near that red line when it's under power. A loop across your chest to ground will almost certainly stop your heart so be very careful.

Check the flow control sensor in the input side of the water line, that often will stick and prevent the tube from firing. The bigger cabinet machines also have a heat detection system that stops the tube if it gets too hot.

A bubble in the tube (mirror end) can cause the problems you are having as the air bubble doesn't allow the heat to be taken away by the water.
Overheating due to lack of water or bubbles would be my first port of call followed by a check of the flow sensor and door interlocks if you have them.

If one of those then I'd suspect the tube or PSU, with the side door open look for a green light on the PSU, dead tubes usually cause an arc to ground when trying to find the path of least resistance so in the case of no arc and none of the above issues I'd then start thinking faulty Power supply.

Tube/supply can be tested but NOT at the red end of the lead. That is nasty voltage your dealing with that can jump quite a gap in air.

best wishes

Dave

[herby08]

Hi there
I have put a mA meter (20mA) between the ground wire ( usually black small wire on the tube ) this gives me a staedy controll about the output to the tube.
greetings
walt

Originally Posted by Exsecratio The last place on earth you want any part of your body is near that red line when it's under power. A loop across your chest to ground will almost certainly stop your heart so be very careful. Check the flow control sensor in the input side of the water line, that often will stick and prevent the tube from firing. The bigger cabinet machines also have a heat detection system that stops the tube if it gets too hot. A bubble in the tube (mirror end) can cause the problems you are having as the air bubble doesn't allow the heat to be taken away by the water. Overheating due to lack of water or bubbles would be my first port of call followed by a check of the flow sensor and door interlocks if you have them. If one of those then I'd suspect the tube or PSU, with the side door open look for a green light on the PSU, dead tubes usually cause an arc to ground when trying to find the path of least resistance so in the case of no arc and none of the above issues I'd then start thinking faulty Power supply. Tube/supply can be tested but NOT at the red end of the lead. That is nasty voltage your dealing with that can jump quite a gap in air. best wishes Dave

[Exsecratio]

Bang on Walt, that is indeed the correct way to test the power flow

I had this mental picture of people trying to stick a $5 meter into the input end of the system and the results would have been *less than fun* if they had

best wishes

Dave

[sukelaser]

Hi Peter:
I just see your post in cnc zone. Finally the laser machine have laser beam now and we find the real reason- reci power supply! It is so strange that the new reci power supply was broken without using,also first time we meet this problem! Anyway,the parts is under warranty and as we will send a new power supply for free!
Alice
sukelaser@hotmail.com
Jinan Suke Science & Technology Co., Ltd. - Laser engraving machines, engraving machines, laser cutting machines

[sukelaser]

Ordinary if there is no laser beam,there are a few reasons:
1. the laser tube is broken
2. laser power supply is broken
3.the control card don't have signal or broken
4. the machine have safty switch.if the upper cover is closed,the machine is working correctly.If the upper cover is open,machine have no beam or stop working in order to keep people safe.
5.The machine have water protection switch. If there is no water inside tube or water circulation is not good,there will be no laser beam.
Alice
sukelaser@hotmail.com
Jinan Suke Science & Technology Co.,LTD Jinan Suke Science & Technology Co., Ltd. - Laser engraving machines, engraving machines, laser cutting machines