Thanks @mcdanlj for moving this topic.
@donkjr I recently bought a K40 and directly started modifying it as this is what i like most.
FYI: I’m technician and work at a company for manufacturing excimer lasers for eye surgery, so i know what I’m doing when handling the PSU
When i got the laser it was working out of the box and the laser results where okay. I aligned the beam and everything was fine in this regard, but
i realized, that the Laser switch (the one to enable the laser in the front panel) is without function.
It is a digital control panel, so i have this soft button to en- disable the output, but this just sets the PWM to zero.
The other softbutton to test fire is working.
The Laser Switch is a fat red rocker switch which is connected to PIN 5 & 6 of the PSU. So GND and P.
It doesn’t matter if the switch is opened or closed. The laser can be test fired in any condition.
I then started investigating and found your blog as well as the schematic on Digikey.
I opened up the PSU and started to measure. The switch is working properly and also
the Optocoupler connected to P does what it should. The signal at X42 (Pin 1 of the TL494) toggles between GND and 5V according the Laser switch position.
At this point i’m a little lost and decided to write you this mail.
I want to use the P input for my interlock chain but this doesn’t work if the laser stays enable regardless of the signal on P.
My question is: Is this normal behavior? I would rather expect the PSU to be disabled when X42 is high.
Thanks for your great work and greetings from Germany