Many thanks, it is amazing that so many efforts are being put to help some unknown people on the forum, much appreciated, after carefully studying your post I can say that almost all my concerns regarding the connection are gone, just a few points to double-check:
should I just connect 5v to IN straight since my lps has power control via LAN port?
can I solder 2 LED pins together without removing the LED?
can I pull 5v and ground to opto coupler’s J2(1) and J2(3) from the lps 5v and G pins without connecting an external 5v power source?
PS: I have tried firing with IN to 5v, the max current shows 27-28 mA, recommended current for my tube is 22-24 mA
If you are referring to the remote meter function that can be connected via the cat5 cable it looks like switching the selector switch [see image below] to the right allows the remote control and the “IN” port values to work together. Not sure how they would work together so I would leave the switch in the right position and not connect anything to “IN”.
If you mean to put a wire across the LED1, yes
Yes you can get the 5v and gnd for the opto’s J2 from the LPS.
Firing with 5V on IN shows you what the max current the tube/supply is currently able to run at.
So when you complete the opto connection you should be able to get to that current.
Note: you do not want to run the tube very long outside the recommendations. BTW, I assume you have coolant running :)!
Switch to the right just enables the cat5 remote control, switch to the left ignores it, with the switch to the right you can use both - cat5 remote control and potentiometer between G IN 5v, cat5 remote control has a priority, if you set it to 50% you will control the power by potentiometer between 0 and 50%. But if there is nothing connected to IN, the laser will not fire, does not matter switch left or right. so there should be always something connected to IN. At least this is what I was able to discover by some testing. Will get the new opto and revert with results, thanks!
hi, so I finally got new opto unit and did everything according to your instructions, the lps responds more correctly now compared to direct (5v / IN) connection, while I was measuring the opto output there was no linear scale from 5v to 0 but after connecting to lps and making some tests everything seems to work as it should, I can use full power now as well as to go as low as 3.5%, on TTL laser did not work below 15% for some reason. Many thanks for your and other members help, much appreciated!
So to summarize - for anyone looking to control CO2 lps using existing diode laser control board or any other CNC machine control board, I recommend to follow the next steps:
Find the PWM signal output (usually it is one of the cables coming to your laser).
Find the proper ground (there may be no actual ground coming to your laser, like in my case, so I got weird measurements at the beginning) The easiest way to find the ground is the USB socket case on your board if you have any (post 17).
Measure the actual output from your PWM + Ground, if it’s 5v you can try to connect straight (post 40 second part), if it’s 3.3v, or it does not correctly control your CO2 lps follow the next steps.
Get the opto coupler unit and 100 ohms resistor (post 27).
Follow the instructions to replace the resistor and LED (post 40 first part).
Connect everything as described (post 40 second part).
Many thanks for everyone participated in a thread!
