Hello all, Recently my k40 stopped drawing as much current as it did before.

Hello all,

Recently my k40 stopped drawing as much current as it did before. I have the digital percentage control board and I added a current meter. At 85% it used to draw 20ma. Then, my machine dropped to 10ma max. I thought it was the power supply so I replaced it. With the new power supply installed, max current draw is 5ma. What’s going on?

I bridged the 5v to the laser control in and it draws 5ma max. I thought it was the power connection to the tube so I removed the wire and cleaned it. I soldered it to the tube to ensure a good connection and re-insulated the connection. It still only draws 5ma. I tried a dvm and got the same reading.

Did I get a bad pws? Is my tube going bad? The tube is less than. 30 days old. Or, is there something I’m missing? Suggestons?

What kind of coolant are you using?
What is temp of coolant?

The temp is 22c. I’m using distilled water with a little chlorox to keep it clear.

Possibly the same problem RDWorks ran into? Poor quality laser. Here are some youtube vids of him testing it.

I’m going to go back to the old power supply and see if it goes back to 10ma. I’m also going to change my water.

If that doesn’t work, what’s a good 4ow laser tube?

Thanks. I’ll check out the videos. I’ve seen some of his already.

Why not upgrade to the 50W while you are at it? :wink:

Sounds like the gas in the tube is depleted. Not shooting for long periods, or running at max for too long without a rest can do that. Replacing tube is usually the fix. The input is PWM for power, so bridging it to 5 volts makes it shoot max…in our case 10ma. Your new power supply may have slightly lower voltage out, or not matched to your tube which can affect end current.

I am running into a similar issue… Did you ever pin down the exact cause?

yes, my ammeter went bad and was giving me false information. I also suspect the digital control board that controls the 5v pwm signal wasn’t reliable either. I’ve replaced the ammeter with a combo Volt Meter/Milliampmeter and the digital control with a simple high resolution pot. I now have much greater control of my laser power for cutting and engraving.