Laser intermittent firing

[Eric Adams]

I have a 90 watt 600mm x 1000mm C02 from Rose Graphix and a CW-5200 chiller with a flow sensor. I bought the system used from a local seller a couple years ago. I did not receive any manuals with the machine. It has been working fine with no noticeable reduction in power.

Today I started a job and the laser was not firing. I stopped the job, returned the head to Home, hit the pulse button a couple times and it fired fine. So, assuming the gremlin moved on to the neighbor's house, I started the job and it completed the job without further problems.

I immediately loaded up my second job and pressed start. It started engraving and ran fine for about 5 minutes, then the laser stopped firing. The temperature on the chiller is fine and I'm not getting any alarms.

Could it simply be the power supply for the tube? Or a bad connection somewhere? I'm not sure where the dangerous "sparky" areas are on the machine.

I tried to film it, so hopefully this will help diagnose possible problems.

https://youtu.be/g_E-lhAXW8Y
https://youtu.be/LFYnCOv_mek

[Dave Vigness]

Three things come to mind, all electrical. I would expect a tube to fade in and out, not cut on and off.

I would be tempted to pull and re-seat the connectors between the controller and laser PSU first, could just be an old / corroded / dirty connection.

1. A bad connection some where, Controller to laser PSU, or laser PSU to tube. I would rule the last one out if you don't hear any arcing.

2. Bad output from the controller. Pull the AC from the laser PSU, and run the controller at 100% and check your 5V from controller to laser PSU.

3. If that all checks out, then you are just about down to a bad laser PSU.

[Eric Adams]

Thank you Dave. I'll be honest and admit that everything you said went clear over my head since I don't know what any of the electronics are under the hood. But I found a video that showed how to use the test button on the laser PSU and when I disconnect the plug and hit the test button, the laser LED does not light up. When the laser is functioning correctly, the red LED flashes brightly with each pulse of the laser and the yellow LED is nice and bright. But when the laser is not firing or intermittently functioning, the yellow LED is very dim and flickers a bit and the red LED is off, aside from when it randomly fires successfully.

It seems strange that the laser PSU would still intermittently function. I tried running a job last night that calculated out at 10 minutes. After about 5+ minutes of engraving reliably, the laser pretty much stopped firing (looked like it was engraving braille). I canceled the job and went to bed. LOL

I think I'll call the laser manufacturer / reseller tomorrow and see if they can help confirm the laser PSU is the problem.

Thank you again for your help Dave.

[Dave Vigness]

Do you have any kind of a test meter?

The cable you are looking for is from the controller to the laser PSU. I don't have a diagram in front of me, but I believe it's CN5 or CN6, but don't hold me to it. They should be labeled as Laser 1 and Laser 2. The laser PSU end is the simplest. You have the line voltage on one connector, and the feed from the controller on the other. You can trace that wire back to the controller if necessary.

The controller puts out any where from 0 - 5V to the laser PSU as a control signal. The laser PSU takes that variable low voltage and puts out a variable power output to the laser tube, just at a MUCH higher voltage.

The simplest would be to 'hotwire' the laser PSU, it only takes two small gauge wires, and run that long program you were talking about. It will ruin full time, no stopping between lines and cuts and engraving, but it takes everything else out of the equation. If it still sputters and dies, then it's the laser PSU or the laser tube itself.

[Eric Adams]

Thank you again Dave for your help. I called the laser manufacturer and they are sending me a new power supply. I showed him my YouTube videos and his thoughts were either the tub or PSU. Their PSU price was lower than anything I found online so I'm a happy camper. Hopefully it resolves the issue.

[Eric Adams]

I ordered a new laser PSU from the manufacturer, but that sadly did not solve the problem. Is this the controller you're referring to Dave? If it turns out the controller is bad, do you have any suggestions on where to buy? Or is this something I need to get from the laser manufacturer?

https://drive.google.com/file/d/13GkqpU ... sp=sharing

[Gene Uselman]

That is the controller- probably a 6442 [Ruida]. I have never heard of a controller cutting in and out as described but anything is possible.My guess would be a bad connection... which can be hard to find. The terminations at the ends of wires would be prime suspects, or an internally broken [inside the insulation] wire. I would start with the wire from the controller to the HiVoltage PS- if it looks OK, replace it- nothing special about it.

[Dave Vigness]

I would second the termination problems. When I changed controllers I had many connections that the crimped ends just fell off.

[Eric Adams]

I was unable to find any loose terminations, though I did manage to shock myself twice... But on the plus side, I now know there's constant power at the back of the on/off button on the front control panel! LOL

My problems seemed to start after relocating the machine to a new spot in my shop, and I'm wondering if maybe the machine rolled/pinched the chiller's alarm cable. Can I simply disconnect the alarm cable wires from the Ruida controller to disable the laser cut-off feature? If it's a bad cable, the laser should resume firing correctly, right?

If it turns out the cable is bad, where can I buy a replacement? Or can I simply buy a suitable 2-wire and splice it into the existing plug on the current cable?

[Pete Cyr]

I was unable to find any loose terminations, though I did manage to shock myself twice... But on the plus side, I now know there's constant power at the back of the on/off button on the front control panel! LOL

My problems seemed to start after relocating the machine to a new spot in my shop, and I'm wondering if maybe the machine rolled/pinched the chiller's alarm cable. Can I simply disconnect the alarm cable wires from the Ruida controller to disable the laser cut-off feature? If it's a bad cable, the laser should resume firing correctly, right?

If it turns out the cable is bad, where can I buy a replacement? Or can I simply buy a suitable 2-wire and splice it into the existing plug on the current cable?

-Can I simply disconnect the alarm cable wires from the Ruida controller to disable the laser cut-off feature?
Yes
-can I simply buy a suitable 2-wire and splice it
Yes

If you have a meter check continuity in the cable - (remove the cable from the circuit)
If you don't have a meter you can still do a check with a flashlight bulb a AA battery and a couple of paper clips (just make a circuit with the cable battery and bulb - the cable works if you can light the bulb