[sli21]

hi all
i have a 60w Chinese LE with a TopWisdom TL-403C controller board. It has a current potentiometer on the control surface which help[s fine tune current output from the laser but thi seems to act independently of any power settings made in LaserCarve (Corel plugin). Is anyone familiar with this controller? I would appreciate some advice. Many thanks and wishes!!
cheers scott

[robertk925]

sli21:

I don't have this machine/controller so this is kind of a shot in the dark, but typically machineswith potentiometers (usually the 40W variety that are controlled by MoshiDraw) use dumb controllers that can't vary the laser power via software control. So the potentiometer is the only way to control the laser power. It sounds like your machine has a smart (DSP) controller AND a potentiometer. In this case I would assume that both work to control the laser power. The potentiometer controls the max amperage that the laser power supply can provide, and the software tells the controller what percentage of that the amperage it should use to power the laser. Do you have an ammeter (amp meter) on your machine as well to tell you at what amperage the potentiometer is setting the power supply?

-robertk925

[sli21]

Hi Robert
Thanks for the post. I did some work today and gained a better understanding. The control surface also has a switch that switches between the potentiometer and software control - ie. When switched to potentiometer, any adjustments is thru the pot and seems to ignore any settings in The software. Viva- versa seems also to be true - when switched to the non-potentiometer path all control seems to be out of the software.
Does this seem sensible to you
Cheers scot

[robertk925]

Hey Scot:

Sounds strange to me. I am not an electrical engineer, but I would think a potentiometer would be hard-wired in the laser power circuit to always be active. Do you have an ammeter on your machine?

-robertk925

[sli21]

Hey Scot:

Sounds strange to me. I am not an electrical engineer, but I would think a potentiometer would be hard-wired in the laser power circuit to always be active. Do you have an ammeter on your machine?

-robertk925

Hi Robert
Yes there is an ammeter on the machine and if u set the sw.itch to potentiometer control then u can vary the power from 0-30ma. I set it at 24ma max if I need full power. In this case it seems to respond to the speed set in the software job.
If I switch the pot out then it seems to respond to the power set in the software. In thus case the pot makes no duff and if I I set the power to 100% in the software it onlys draws about 10ma max and struggles to cut. Seems strange to me.

There is a setting on the control surface where I can set pwm (Hz), min power, max power, tube type etc. the power setting is explained as tube duty cycle in the hard to understand manual. If I lower the max power to say 60% the power seems to increase.

I have the pwm set to 5000hz, seems from what ive read that with co2 tube it doesn't make much difference what pwm is.

I'm confused I must admit.
I think I have managed to find a contact from the company who makes them so I will see how I go.

Any thoughts on any if that? I appreciate your input
Cheers scott

[robertk925]

Hi Scott:

Ah, I think I understand better. So there is a physical switch that bypasses the potentiometer, sorry I didn't understand that from your previous email.

That's very strange that bypassing the potentiometer and setting max power to 100% in the software only gives you 10ma. Again, not an EE, but I would expect the potentiometer would only be able attenuate the power. Sounds like the software settings must be screwing something up, perhaps overtaxing the power supply?

I found this article that might help explain the interaction of PWM, power, etc. It sounds like he is having a very similar experience to you.
DIY Laser: Laser Power Settings Via PWM Can Fool You

-robertk925