Laser Leak

[Zsolt Paul]

Just wondering if any of you had "laser leak" before? What I mean is that when the laser is supposed to be OFF (not firing) and just moving the laser head around you can see a VERY LOW power of laser beam "leaking out". Its powerful enough to mark acrylic (though it won't do anything to materials that need more power to mark). This is the 2nd time I have had this in 3 years! Its a high quality Synrad tube in a Vytek machine. Its definitely a synrand issue. I sent it back to them last year (the whole tube and RF supply ..man, what a pain...) and it worked great for about a year and now its doing it again. I though it was a fluke, but at this point, I gotta wonder....

[Robert Rosensteel]

Hello Paul I had my laser for about 1.6 years and saw the same thing with leather and acylic. Called Xenetech and they told me to check the tube before the first mirror with sheet of paper.(machine on laser tube not running) I did and it burned a spot. They said to ship the RF unit,power supply and the tube. So I built a crate and at my cost shipped it to them. They called and said that the tube needs to be shipped to Snyrad Washington State(at my cost). And a up front $500 non-refund fee would be charged for them to look at the tube. And$1000-$1500 to repair I asked that they ship the unit back to me. When I put it back together it worked fine with no burn marks. About 4 months later it started again but not as bad. I have learned to live with it. Thats about all I can tell you NOT HAPPY BUT WHAT CAN YOU DO. ROBERT

[Richard Rumancik]

Just wondering if any of you had "laser leak" before? What I mean is that when the laser is supposed to be OFF (not firing) and just moving the laser head around you can see a VERY LOW power of laser beam "leaking out". . . . I sent it back to them last year (the whole tube and RF supply ..man, what a pain...) and it worked great for about a year and now its doing it again. . . .

Did Synrad or Vytek not suggest adjusting the tickle setting before sending it back? Does your Vytek not have an adjustment on the main board? Maybe the problem is something other than tickle setting but sure would sound like it. The Synrad manual should tell you something about how it functions. If Vytek did not implement an external adjustment, maybe a technician can figure out a way of adding it on based on the Synrad specs. Part of the tickle circuit must be on the PCB inside the tube; maybe that's why you had to send it back. But there should be a way of fine-tuning the tickle setting outside of the tube enclosure - most of the laser systems seem to have a way.

[paul mott]

The Synrad tube does have an adjustable internal ‘Pulse Stretcher’ circuit but Synrad give no details of how this is to be set so personally I would not even attempt to adjust it.
The tube requires an external ‘tickle pulse’ which has to be 1us wide repeated every 200us (5kHz) and your controller board will provide this and should have a fine adjustment for this feature. If the pulse is any wider or repeated at a higher frequency than 5kHz then the tube will ‘leak’ as described.
In the absence of any manufacturers information, obtain the use of an oscilloscope and measure the ‘tickle pulse’ (this is generated when the tube is in standby, waiting to be triggered), if it is any wider than the 1uS (which is what I would suspect) trace the signal back and you should find the adjustment.

Paul.

[paul mott]

As an addition to my earlier post - on an oscilloscope the 'tickle pulse' looks like the lower trace in this pic.

Paul.

177211

[oscar martinez]

I adjust mine like richard says I have a spirit gx 60 watss , when i bougth my machine i notice that with row mark materials or plastic and related. I contact my dealer and adjust my . I jus open a box with a lots of screw arround And follow the technician instructions it seems complicated but is not I lower a potentiometer like to two numbers down and the bledding disapear no problems my machine no longer damage any rowmark materials with the machine not running. I have pictures of the box i open
Atte Oscar .

[Richard Rumancik]

. . .The tube requires an external ‘tickle pulse’ which has to be 1us wide repeated every 200us (5kHz) and your controller board will provide this and should have a fine adjustment for this feature. If the pulse is any wider or repeated at a higher frequency than 5kHz then the tube will ‘leak’ as described.
. . .

Paul, I saw this pulse info in the Synrad manual for the 48 series - not sure if it is the same for all their lasers - but what I was wondering is what parameter is actually being adjusted when you externally change tickle on the mainboard (say on the Mercury)? They have a bank or resistors that somehow fine-tunes the tickle - is it adjusting the width of the nominal 1 us pulse?

[paul mott]

Richard,

I honestly don't know.
The circuit I designed for my first RF laser controller has two adjustments - the upper pot will adjust pulse repetition frequency (5kHz +/- 10%) and the lower pot will adjust pulse width (1uS +/-10%). Either or both of these pots could be replaced by a couple of software selectable resistors or chains to allow variation.

Paul.


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[Richard Rumancik]

Thanks Paul. I thought I'd find the info in the manual for the 48 series but I could not see anything as to how one fine-tunes the tickle externally. Obviously the OEMs have a way, but Synrad does not seem to publish it in the basic manual. Synrad's stand-alone controller puts out the pulse waveform that you suggested; no mention of tweaking frequency or pulse width to change the degree of tickle.

Zsolt hasn't replied as to whether the Vytek machine has an external tickle adjustment.

[Zsolt Paul]

Sorry everyone for the delayed response! I do not know if the vytek has an external tickle adjustment. Vytek hasn't told me if it did, but they did say I can not do this myself. However, they did offer to do it for free if I send the FR unit to them, so that's good! This also means that this RF unit can be adjusted and they don't need the laser tube itself. Obviously, there is some machine that can be hooked up to the RF control and make the adjustment. I would LOVE to be able to do this myself, as this is something that will need adjusting from time to time it seems and I don't want to have to ship it in every time.