Constant firing at low voltage in idle mode

[J-Ro (Julian Rojas)]

I’m having an issue with my 100W RF Laser, controlled by a Ruida RDC6445G.
When the machine is turned on, although there’s no job running, the tube constantly emits a very weak beam. Obviously it should not be lasing.
My electrician friend checked the wiring for damaged wires, but says it’s all good. He assumes that there’s a current inducted into the one of the wires that carries the signal for controlling the laser.
I don’t know, since I replaced the old leetro MPC6565 controller (it was broken) with the ruida i think maybe i’ve got one of the settings or wirings wrong.

Someone has an idea how to solve this?
Thanks in advance!

settings.lbset (14,3 KB)

[Kuth (Luis Jardim)]

I understand very little about this type of laser, however this seems to me to be a problem with the output to the tube or the controller itself. The ideal would be to measure the isolated output for the tube in order to understand whether with the “output in the air” (with nothing connected) there is any type of voltage.

[jkwilborn (Jack Wilborn)]

I’ve looked at lots of the Ruida manuals on how an dc excited machine is wired. You wiring looks fine.

Before you change any controller values, make a backup of your factory or original settings that it has.

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Not having one of these animals, I will give you what I do know about them and that might lead to an answer. We have a couple users here that might be able to help.

The dc excited co2 laser is wired a bit differently but an explanation might help you.

There are two control lines to the lps. PWM sets the current limit via the IN pin. This runs continuously anytime the machine is executing a layer.

The L-On or Laser Enable goes low causing the machine to lase at the IN current limit.

An RF excited laser is driver with only one control line, that is PWM from the controller, L-On is not used. This is RF mode selectable Edit → Machine Setting → Laser Settings

These have a pre-ignition value that is adjustable, this can be disabled in the settings.

It would seem these are driven like a ssl. Based on the fact that pwm period appears to make a big difference. I’ve looked but have never found much on the moudle itself.

All of this has only the pwm connection for control… That’s about my limit.

Everything following is an opinion, ensure you follow and the risk is yours.

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I’d suggest reading the voltage from the Ruida pwm terminal. This is the control line to the laser module. It will be a very small voltage. 20% power should generate about 1V. That would be near 10W on your machine, so I’d guess it’s a lot less, more like 1%… or about a tenth of a volt.

I’d try changing it to RF (no pre-ignition)… I don’t think there is any reason that this might damage your machine in any way. Just the resulting burn.

If this changes it, I’m not exactly sure what it tells us, but it’s information we may be able to piece together.

Good luck

[J-Ro (Julian Rojas)]

Thank you for the quick response. I will definitely try to measure the output - at this time I think the most probable cause is a constant voltage where there shouldn’t be one.

[J-Ro (Julian Rojas)]

Thank you for your response!

@jkwilborn

I’d suggest reading the voltage from the Ruida pwm terminal. This is the control line to the laser module. It will be a very small voltage. 20% power should generate about 1V. That would be near 10W on your machine, so I’d guess it’s a lot less, more like 1%… or about a tenth of a volt.

You mean measuring the voltage on the wiring (the wire plugged into the the LPWM1 slot)? Or any other specific wire?

Changing the Tube Type to “no pre-ignition” didn’t change anything.

I’ve found this in the Ruida manual:

Unfortunately, i couldn’t find nor access this menu on my controller. Maybe it could have helped.

[cggorman (Chris)]

It says effectively configured on PC software…reading between the lines…maybe like when configuring a router, you connect directly to the IP address?

[jkwilborn (Jack Wilborn)]

Thinking about this, I’d unplug CN5 and see if it still showed these symptoms. This is all the control lines to the laser module.

Most of these have the inputs setup so there is no lasing without the control lines being active. This would isolate the controller from the laser module. If it still had an output, I’d suspect the laser module. Conversely suspicion falls on the Ruida, and I’d think it’s probably some type of configuration issue. Most of the time, it isn’t a hardware problem just a configuration issue. I’m hoping that’s the problem here.

@J-Ro

voltage on the wiring

On the Ruida, measure from the PWM pin to ground.

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Sorry changing to no pre-ignition had no effect. I don’t know what this actually does since this is really only one control line to the laser module. Thought it was easy to check and can be changed back quickly.

@J-Ro

Ruida manual

This is likely screens from the RDWorks software… You can run it, it’s rather unpredictable and you usually need multiple copies of it. Some versions have options not included on all versions. It doesn’t run natively on my Ubuntu box, so I have virtually no experience with it.

All of this is supposed to be accessible via the machine console. You might need a password. There is a bunch of them… similar to RD8888. Some things can only be changed via the console.

@cggorman

configured on PC software … you connect directly to the IP address

This is probably likely, with their software. I connect to mine via the Ethernet port.

There are some things that you must do via the console. The only way to set the user origin, is via the consoles origin button.

[Explosive_Apparel (Richard Neath)]

Image 1. Is that wire intentionally just left out of any connector with no shielding etc ?

or does it just look that way ?

[J-Ro (Julian Rojas)]

Yeah, that is I think the Z-axis limiter. I had issues setting it up correctly, when it didn’t work out I just left it there and I live with it. i tried plugging it in now, changed nothing.

[J-Ro (Julian Rojas)]

@jkwilborn

Thinking about this, I’d unplug CN5 and see if it still showed these symptoms. This is all the control lines to the laser module.

Most of these have the inputs setup so there is no lasing without the control lines being active. This would isolate the controller from the laser module. If it still had an output, I’d suspect the laser module. Conversely suspicion falls on the Ruida, and I’d think it’s probably some type of configuration issue. Most of the time, it isn’t a hardware problem just a configuration issue. I’m hoping that’s the problem here.

I did as you suggested. Unplugged the CN5. Still having the same issue But at least I think we are narrowing the problem down.

[J-Ro (Julian Rojas)]

When looking at the Laser tube itself, it is firing in Idle mode and the red lasing LED is flashing (in a weak an irregular way, just like the emitted beam). This happens when CN5 is connected.

When i unplug CN5, it still lases the same way, but the red lasing light is off. Very weird behaviour.

When I unplug the circuit board from the tube, it stops lasing. Still, the tube has the power wires connected. So I guess it has to do something with the circuit board?

[jkwilborn (Jack Wilborn)]

@J-Ro

unplug CN5, it still lases the same way, but the red lasing light is off

Sounds like it’s the laser module… The red lasing light is probably the pwm from the Ruida…