Hello Guest it is April 19, 2019, 04:52:20 PM

Author Topic: DC-K40 Laser conversion issue  (Read 26626 times)

0 Members and 1 Guest are viewing this topic.

Re: DC-K40 Laser conversion issue
« Reply #20 on: August 06, 2014, 11:07:11 AM »
Tweakie,

Thank you sir, you are truly brilliant!  the mechanicals of my design loosely based off of Barton Dring of buildlog.net 2.x laser cutter, but since i a using a cnc controller board instead of a dsp i have had issues getting it to work properly.  but had i not ran across some of your other postings across the web about using "magic z" to control the firing, i would have not able to get this far!

i love to build stuff and i have a very, very limited budget which causes much conflict to be sure.  without people like you and Mr. Dring paving the way, i would surely be in the stone age.

again, thanks!

-derrick
Re: DC-K40 Laser conversion issue
« Reply #21 on: August 08, 2014, 12:37:10 PM »
It sounds to me like you are experiencing a difference in potential between the GND connections between your computer LPT port and the machines PSU GND.

The LPT port’s pins 18-25 are GND and one of these pins must be connected to the laser PSU’s GND point (adjacent to the TTL(L) signal input as shown in my earlier diagram),

This should resolve the problem of the laser firing when it should be off.

Sadly, it does not...  I went this morning and wired up the new board (pin7, pin25) gave it a test drive.  BTW if anybody is interested, the TB6600 vs TB6560 believe it or not makes a HUGE difference in the sound of the machine.  so much quieter now...  

except for, it won't stop firing!

here are the details:  it is wired exactly as in the diagram.  before i was pulling the ground from the board, now it is soldered right to pin25.

what it does:
1) test fire button works just fine.
2) red laser led barely lights up when the laser control screw terminal is plugged in and goes out when unplugged.  it brightens to full on when the test button is pressed.  this is regardless of whether the    pot is wired in or not and/or the setting of the pot.
3) laser is completely off until flood(relay) is on and then the tube sputters or flickers burning lines wherever it goes.
4) the only way to turn the laser off it to either unplug the screw terminal or to turn the pot down, in both cases of which the laser won't fire.

what I've tried:
1) two different computers
2) two different power supplies (i picked up this power supply because i thought there was a malfunction with the first which i bought used off ebay)
3) three different driver boards (expensive lessons learned!!!)
4) used pin 7 as both z direction and digital out
5) wired the power supply with and without potentiometer.

so if you have any advice or suggestions, that would be greatly appreciated.  I am at a loss as to where to go from here.  does the pin # make any difference?  i am not to well versed in parallel ports and haven't used on since the days of the dot matrix printers; i'm a programmer not an engineer!

-derrick
« Last Edit: August 08, 2014, 12:39:05 PM by odditique »

Offline Tweakie.CNC

*
  • *
  •  7,708 7,708
  • Super Kitty
    • View Profile
    • Tweakie.CNC
Re: DC-K40 Laser conversion issue
« Reply #22 on: August 08, 2014, 12:48:51 PM »
Hi Derrick,

Sorry to hear that you are still having problems with this.

I need more details, could you post (or email me) details of your connections (circuit) perhaps a diagram and pictures. The problem will be something simple but, so far, it is proving illusive to find.  :)

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: DC-K40 Laser conversion issue
« Reply #23 on: August 08, 2014, 01:36:01 PM »
ok, i didn't have time to draw a wiring digram, but it is wired exactly as the original diagram in this post, aside from using pin7 instead of pin4 (that's my Y pulse pin).  here are a few pictures with some notations.  in the picture with the label, the laser led is on (it looks brighter in the picture than it really is), but the laser is not firing because of the interlock.


wiring to the board


my wiring


firing the laser, the led lights more

The wiring is a bit of a mess right now because i haven't done any cable management until everything works properly

Offline Tweakie.CNC

*
  • *
  •  7,708 7,708
  • Super Kitty
    • View Profile
    • Tweakie.CNC
Re: DC-K40 Laser conversion issue
« Reply #24 on: August 09, 2014, 01:33:12 AM »
Hi Derrick,

If I am understanding correctly, you are using LPT Pin 7 as your laser trigger.

How is that configured in Mach3 Config / Ports & Pins / Motor Outputs ?

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: DC-K40 Laser conversion issue
« Reply #25 on: August 11, 2014, 10:39:12 PM »
sorry, out of town for last two days.  i have pin 7 configured as z-dir, not inverted.  i also tried to use pin 7 as digital out, but that didn't make any difference either.

Offline Tweakie.CNC

*
  • *
  •  7,708 7,708
  • Super Kitty
    • View Profile
    • Tweakie.CNC
Re: DC-K40 Laser conversion issue
« Reply #26 on: August 12, 2014, 01:52:08 AM »
Hi Derrick,

Try changing your Mach configuration so pin 7 is active low (inverted).

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: DC-K40 Laser conversion issue
« Reply #27 on: August 14, 2014, 10:37:45 AM »
Hello Tweakie,

i gave that a try this morning an still a no go.  when i get home tonight i am going to test the actual parallel port and check the voltage coming out of the computer.

Offline Tweakie.CNC

*
  • *
  •  7,708 7,708
  • Super Kitty
    • View Profile
    • Tweakie.CNC
Re: DC-K40 Laser conversion issue
« Reply #28 on: August 16, 2014, 03:23:52 AM »
Hi Derrick,

Perhaps you could perform this simple test…

Remove the red wire (connected to LPT Pin 7) from your laser PSU. With the Pot set to < ¼ power level, switch on the system – does the laser fire continuously ??

Measure the voltage between the “L” terminal and the “G” terminal on your PSU (with the system powered up and the red wire still disconnected) is it 5 Volts ??

Tweakie.
« Last Edit: August 16, 2014, 03:43:23 AM by Tweakie.CNC »
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: DC-K40 Laser conversion issue
« Reply #29 on: August 18, 2014, 12:07:27 PM »
Hello Tweakie,

So this is where i now stand... yesterday i had the idea that the problem might lay in the board itself because as i was getting ready to conduct your tests, i noticed that the laser led was dimly on when the board was not connected to the parallel cable!  so thinking that there might be some stray voltage the board, i went to radio shack and got a female parallel port head and proceeded to solder a new cable leaving 7 and 25 free to wire directly into the laser psu. after spending all night with that crappy radioshack junk (had to re-solder because the connections kept coming undone), i went out and plugged it in and ...... same thing.  so i went and hit everything with an ohm meter this is what I'm getting:

L - G on psu 1/4 power: 0.0v
G - red wire (disconnected): 3.10 - 3.50v
pin7 - 25 (laser fire): 0.15v
pin7 - 25 (laser off): 3.1 - 3.40v
switched to pin 8 and same results.
switched to pin 7 as digital0 out, same results

so my conclusion is that it appears that my parallel port operates on 3.3v and fluctuations are causing the laser to think that it's being fired super fast because its fuzzy around the ttl/tth cutoff.  Does this sound about right?  I read that your parallel port mode in the bios could make a difference, but in the bios of the machine I'm using (emachines t5088) there are no options to change the parallel port mode (super basic settings).  Is it possible that i just may need to pick up a parallel card?  or is there a trick that could be done with a resistor to pull it up to 5v without damaging the p-port?

thanks,
derrick