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IndustryArena Forum > Laser Engraving and Cutting Machines > Commercial Laser > G.Weike Laser > Possible Causes for blowing Inrush Current Limiter on Power Supply
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  1. #1
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    Possible Causes for blowing Inrush Current Limiter on Power Supply

    I have a 8 yr old G Weike 1290 100 watt laser. My power supply has zero markings on it except 110 written in sharpie. The power supply was swapped by a tech when it was installed brand new because the original didn't work.

    I take very good care of this machine. It has been getting way more use than usual the past 6 months at higher power settings than I've run it in the past 8 years. I replaced the RECI tube about 4 weeks ago - same as the one I had.

    Today I had been running it for a few hours and heard a "squee" at the start of a job. The motors kept running but it refused to fire. I still had power to all other electrical components. I went through safety switch check etc. I decided it was probably the power supply after reading through some very helpful forum threads. I do not have an extra... duh duh duh, so I will be down for a few days.

    I opened up my power supply and I found a pretty awful looking component. I'm pretty sure I found it DigiKey MF72-005D20 INRUSH CURRENT LIMITER and ordered a few so I can fix this power supply for a backup. I'm hoping this thing is just old and couldn't hack it anymore, but I fear this blew because of an underlying issue.

    My question is, what would cause a current limiter to blow and is there anything else I should be checking on while I wait for my parts? I can rewire a whole building with AC power, but I'm a dum-dum when it comes to DC.

    One more thing... for the life of the machine I've always walked over the machine control panel to start the job but I got lazy and a 2-3 times in the past week I've hit START from my LaserCAD software... which is what I did the moment this thing blew. Coincidence? I have a 20' long usb/printer cable from my computer to my laser which I know is pushing it. Could that have been the problem?

    Thanks!

  2. #2
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    Re: Possible Causes for blowing Inrush Current Limiter on Power Supply

    You are correct, the current limiter most likely blew up because of an underlying problem with the power supply, such as shorted transistors and/or diodes. Don't try to simply replace it without checking the rest of the circuit first. Keep in mind that a bad part does not always look bad - you need to measure it to make sure.

    If you are not intimately familiar with electronics, it might be a good idea to find someone local to help you. We (the forum members) will assist you the best we can, but there is only so much that can be done remotely.

  3. #3
    Community Moderator Al_The_Man's Avatar
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    Re: Possible Causes for blowing Inrush Current Limiter on Power Supply

    Did you get the correct part No. off of the old one?
    There is a possibility that it failed due to aging, as they take a surge every time at switch on.
    There is also a max capacitance level value that can be used (inrush) , if this somehow has changed, it can cause premature failure.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  4. #4
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    Re: Possible Causes for blowing Inrush Current Limiter on Power Supply

    I bought some inrush current limiters and I bought two new power supplies (one as a backup). I installed one of the new power supplies (the other should be here this week) and am not going to fool around with the old PS for now because I'm on to oh-so-many new problems. My mA meter is spiking up to 40 at 100% power and anything I'm sending to the machine at over 25% power seems to be reading at 100% power. So any job I send over 25% power has the mA meter reading way too high. Any job I send below 25% power and the mA meter stars to go down.

    The laser has never fired at a job sent below 10% power but now I'm finding 100% of my power range goes from 1-25% from my LaserCAD software and I'm sending some jobs at 6% power. My power supply is rated at 80-100 watts, and I was thinking I'd turn the potentiometer down even though I have a 100 watt tube? I'm stumped and looking all over the web for answers...

    Don't ask me what my mA meter was doing before this because it's not something I look at unless I'm having a problem. I'm wondering if I actually have a 80 watt tube (installed new last month) and a software input problem rather than a power supply problem now. If anyone can tell me where to change the tube wattage in LaserCAD v.8.10.21 I'd be happy as a clam. I think I'm going to have to reinstall an earlier version of the software because earlier versions had that option in manufacturer parameters (max power). This version does not, so what does the software think my tube wattage is? Beats me. There's no way to input on my machine control panel either.

  5. #5
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    Re: Possible Causes for blowing Inrush Current Limiter on Power Supply

    Uh well, I've learned a lot and wasted my long holiday weekend figuring this one out. HY-DY13 power supplies have the same model number on 80-100 watt (RECI W2 tube) and 100-120 watt (RECI W4 tube). I guess the settings (most likely the potentiometer) are adjusted in the factory. They are both sold as the same model number, but with different wattage specs. I guess I had a power supply that was adjusted for too much power. I had a backup backup PS that arrived yesterday and that solved the problem. I don't know what happened to the first PS that blew but for now, everything is working fine.

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