2012 DSP Laser Firing on Reset/Power Down

[twehr]

Ack!

Is there any recommendation on how to solve the laser firing when power is removed from the machine? Previously the recommendation was to switch to TH for laser control, but now that's not an option.

Marco you need to update the wiring diagrams and add some warnings to the store item for the 2012 DSP. This basically means in all setups the 2012 DSP has uncontrolled firing of the laser which is a BIG issue.

You could try putting an inverter between the DSP card and the TH. The controller will still be acting normally, but the inverter will take it's "lows" to "highs" which will fire the laser. When powering off, the controller will still go low, but since the inverter is ALSO powering off, it cannot invert the controllers signal - thus the laser will not fire. I am not an electronics engineer, but seems this should work.

[Gadroc]

Thanks,

I'll look into setting that up.

[baccus61]

Mine does it on TL sometimes as well. I just don't press the LASER button on the LCD any more as 1 out of 3 times will turn the laser on and it stays on. It's intermittent on my rig.
Rich.

[Engineerable]

I'm having the same problem as well of the laser firing on power down using TL.

[wctx1977]

Mine does the same thing and I never thought that would be a big issue but now I begin to see that it could print an unwanted mark in your material being worked. As Marco said that it is a hardware issue, I assume that the majority of boards being made earlier for the 2012 version will include the same problem, now the question is how to solve that problem without compromising other functionality of the board. May be a new redesigned board would be the answer. Mine as well did not included the network feature and ended paying the same price as the one with it, I thought 2012 board was only one model not two or more boards with different features. That's sad for the consumer side

[Tech_Marco]

Have you tried the patch I posted??
viewtopic.php?f=60&t=837

It may fix the Reset-fire issue, especailly for the 1st patch DSP. You only need one of those two files installed to the DSP card by using the dump drive. If the board is "5.11.10.12", use the 111203V1.UG5. Others, use the 111203V2.UG5

A newer software will be launced in 7 days

Marco

[Gadroc]

Any word on what issues we can expect to be resolved in the new release? Thanks for the continued work on this Marco.

[Tech_Marco]

Ok, thank you for your patience.
Here is the solution:
viewtopic.php?f=60&t=902


Marco

[Gadroc]

Marco,

Does that just fix TL laser fire on shutdown, or is it supposed to fix being able to use TH?

[Tech_Marco]

It fix the unwanted-fire from happening during power is shutting down when TL is used. Unfortunately, the 'TH' issue can't be solved on AWC-608 as more hardware issue involved. They're working on a new board with both TH and TL issue fixed.

Marco

[Tech_Marco]

Tested the modified board today and found that the solution was working!
Before the modification, the laser fire when power to the DSP was disconnected. After modification (removed 6 componenets), no fire triggered after power removed from the DSP.

Marco

[wctx1977]

Tested the modified board today and found that the solution was working!
Before the modification, the laser fire when power of the DSP disconnected. After modification (removed 6 componenets), no fire triggered after power removed from the DSP.

Marco

Hi Marco!

Do you know if removing this 6 components affect the board in any other way?
Thank you!
Edgar

[hilo90mhz]

It looks like the main component that caused the problems were the 4 diodes (2 for laser #1 and 2 for laser #2) these prevent the output pins from going above 24V rail voltage or below ground - which also effectively pulls the output pin to gnd as the 24V rail on the DSP board is dropping to zero on power off which I think is where the problem came from.

If the DSP and the laser power supply shared the same 24V supply it wouldn't be a problem, but the laser PS has larger capacitors and therefor stays power up longer. If I am right you really only need to remove one of the diodes for each channel (the one to the + rail), but might as well remove both.. It just makes the outputs a little more vulnerable to static and being connected wrong. In normal operation connected to the laser power supply this should be no problem. If you are only using one laser channel you only need to remove the resistor next to that channel, and the diode that goes to the +24v rail (closest to the corner of the PCB for channel 1) - so only two parts

For laser power control and to be sure the laser is never driven over 17MA I would highly recommend the series variable resistor idea that Tim suggests here:
viewtopic.php?f=8&t=862#p3038

That will solve the other problem aswell of making 50% power in the program actually be 50% of the available power - AND prevent any software/hardware issues from destroying your laser. Just don't change the variable resistor setting

Cheers,
Chester

[Gadroc]

Any recommendation on the parameters on the resistor? Should I use 25k, 50k, 100k?

[hilo90mhz]

** Update ** I was wrong - marcos fix does work. See following post

Okay the problem with "unwanted fire during power off" has not been fixed.. I just made the modifications Marco recommends(removed both diodes and resitor) and using a simple logic tester I can still see the current blip at turn off. It is much better than before, with only a short burst of current, and not continuous after power off. But still not gone yet. Will be reverse engineering the opto isolation circuit with possible solution later today.

For the variable resistor I will measure the output impedance of the 608 board today and let you know what value resistor I recommend, quite possibly the 1K variable resistor that comes with these 40W machines will work, but it may load the output pin on the AWC608 too much.

Cheers,
Chester