Thanks guys. I think it's better to use external PWM converter than that of frying something on assumption

I have tried manual connections as well. it doesn't work. Any other suggestions @T3P3Tony ?

@t3p3tony No luck on either way. i have tried those steps you have mentioned.
I have checked connections continuity. everything is fine.
Bu, i have a doubt. once if i configure a heater pin say exp.heater3 and i checked the voltage it shows 0v. but, not configured exp. heater pins shows 3.some volts. it this normal?

I have only the laser config files in my duet. when I switch on the duet . the laser starts to firing.
When in CNC/LASER mode- not firing in CNC mode. if I switch to laser mode it starts to firing.(and if i switch back to CNC mode also still the laser is firing)

and I have checked the voltage coming through the pwm port from the duet pwm board it shows 7.2V.

so, I am going to buy a connecter type 74hct0-https://www.tandyonline.com/74hct02-quad-2-input-nor-gate.html to try out wiring manually.

@t3p3tony Thanks. let me try these step and check

@t3p3tony here my connection to the duet from pwm board

When I switch to laser mode, the laser firing could not turn off by any code (M5). then again if go switch to CNC mode also laser is still firing and could not turn off.

if I unplugged the Pin-8. the laser is not firing.

@sarvan let me take some more clear pics and infos tomorrow

@t3p3tony pin 8 connected to duet laser pwm board

@sarvanin this board also the same thing. Laser firing continuously can't turn off.

@t3p3tony yes always firing in the laser mode.
I thought could be the chip may be issue on the duet laser pwm board. So, I have hooked up another one.

@t3p3tony I have plugged this to the duet ex header.

in the CNC mode even the pin 8 is not connected the laser firing. but, when i switch to laser mode it is not firing.

@t3p3tony ok. thanks