60W tube firing at full power at 60%

[bratan]

Just upgraded my SH-G350 50W cutter to a 60W SP tube and LO 60W power supply. For some reason at just 60% power I'm getting reading a little over 20mA. I now this tube is rated to 20-22mA, I don't want to damage it. Is there something I need to adjust in DSP firmware (rdc644xg controller)?

[Tech_Marco]

If 60% could get you 21~22mA, the you should set the Max_power to 60% on the DSP. That way, regardless what power% you use on your job (even 100%), you could never able to go beyond 60% or 22mA unless you have another power replaced it

Marco

[bratan]

If 60% could get you 21~22mA, the you should set the Max_power to 60% on the DSP. That way, regardless what power% you use on your job (even 100%), you could never able to go beyond 60% or 22mA unless you have another power replaced it

Marco

Thank you, I really wanted to use full 100% range tho. Can PSU be adjusted to lower it's maximum mA output? From what I understand controller is sending 0-5V volts which PSU interprets as 0-100% power output.
I saw screw hole on the front of PSU, but there's no manual so I'm not sure what it does....

[DonL]

There is another thread that discusses this issue, by adding 2 VRs you can set min and max power so that the DSP at 90% will be 90% of your tube's power output and 2% on the DSP is 2% of the tube's output after the preignition current, right now if you select 2% the laser will likely not fire... Tech_Marco was also discussing this with the LaserCAD programmer so hopefully he resolves the issue programmatically rather than resorting to wiring mods.
SEE:
viewtopic.php?f=8&t=2522#p12170

[Techgraphix]

Just another question: is your 22mA your maximum power?
Do you have the possibility to measure the output power?
A few weeks ago I installed a brandnew lasertube in a new build machine and @ 50% we already saw 23mA. Increasing the powersetting to 95% gave the same 23-24mA..
This tube was sold as 60W but my laserpowermeter stuck at 32Watts only.. So this tube doesn't meet the specs and is to be replaced by the seller..
Bad tubes can draw more current.
When my first tube was near the end of its life I saw the current rise to 30mA with the same settings where it was 17mA before.. The outputpower was only 12Watts (from 60) when I replaced it. (together with the cooling.. overheating to 28 degrees Celcius could be the cause.. I cool with a CW5000 now... )

Kees

[bratan]

Thanks DonL, that's great info! I'll see if I can implement pot control. You are right, mine won't fire below 11%.
Techgraphix, to tell you the truth I didn't try it above 60%, I'm afraid to damage to tube... I will check it's output with a laser power meter tho just in case

[Godzylla58]

Hi Lee, I did the same exact upgrade to my SH -350 using light object power supply, 60W tube and added a ma meter. I'm getting a little confused with the power settings as well. Example, if I am cutting and set my min power to 35% and max to 85% and through cut setting at 50%, my ma meter only registers 7 to 8 ma and cuts through 1/4 plywood easily at 4mm/sec. But if I raise the settings to 70% min, 85% max and through cut left at 50% at 10 mm/sec it draws 18 ma. I'm trying to find the sweet spot between speed and power so I can get through cuts without charring at the fastest possible speed. As a note though, I personally went to Lightobject in Sacramento and watched them perform the test out of my new tube with my new power supply. It had 62.5 W at 17 ma. on their bench. I don't have a power meter so I don't really want to go past 18 or 19 ma.... Since it is already over 60W at 17 ma, would it overpower the tube if I took it to 20 ma?

[Tech_Marco]

If you want the tube last longer, you should never drive it by over current. Usually it take 22mA for a 60W to reach full power. But, with new technology and new gas formula for the tube manufacturer, most tube can out perform than the rating we used to have. Say you can get 67W at 17mA, then stay with 18mA and you're totally fine. To lock up the max current the LPSU can delivery, you can adjust the "max_current" on your controller card if there is such feature on your machine. In general, most tube controller should allow one to adjust the peak current for safety of the the tube.

I know it is a little confuse that the DSP controller card is running at 60% or 75% but the laser output in full power. Instead, it should show "100%" for better human terminology.
There is a "to do list" for the DSP controller, as well as the LaserCad for the future update. Now, China is in national holiday and I have to wait for 3 weeks before I can get an update or make change on the hardware and software.

Regards,
Marco
LightObject