Laser power question

[Mark Taylor2]

Hi all,

I've searched for a problem I'm having and not found any topics related. Possible I'm using the wrong search terms.

I have the Micromark Laserknife (40W which I've upgraded to 45W tube and a better lens) which is working very well for me as I'm using it for cutting only (vector mode) and rather thin, exotic hardwoods for my hobby of wooden model ship building. It is basically an upgraded Chinese K40 sold by a US firm. I'm waiting to hear back from their tech support but I thought I'd check here also.

What has started happening is that when I fire it up and hit "test", the mA needle goes to about 4mA and then hangs there while I rotate the Current Regulating control until I hit a certain point and then it jumps to 9mA. I can run it up higher but not down below 9mA. If I do, it suddenly drops off to the 4mA.
So, is my tube going out? Or is it something else I should look at like perhaps a bad control potentiometer? I'm quite capable of dealing with solder joints for testing/replacement so a pointer in the right direction would help.

Thanks in advance.

[Bill George]

Could be as simple as a faulty meter, the needle sticking. Does the machine still work? If not I would look for loose connections.

[Mark Taylor2]

Thanks Bill. You pointed me in the proper direction.

I'm having a head-smacking --- DOOOH!!!! moment. I found two things.. the first was a connection where a plug seemed loose. Re-connected it. Didn't fix it but I felt better for re-checking all the connections. Then I noticed I had two magnets that I use for holding material in the cutter to the table. Those were sitting on the door where the meter and controls sit. The door provides the access to the electronics. I removed the magnets (they were sitting about 6" away from the meter) and miracle of miracles... the needle now moves freely.

I think I'll go stand in the corner and write 1000 times: "I am an idiot." I've spent most of my life working around electronics and meters and failed to think about magnets and meters.....

Thanks again.

[Gary Hair]

I think I'll go stand in the corner and write 1000 times: "I am an idiot."

You'll be in good company...