Laser Cutting Newbie needs help with KH-7050 chinese laser problem!

Hello guys and girls!

First of all, let me put you all into context because i surely need help and still have alot to learn!

I’m a graphic designer in a small advertising shop, we ( the company ) own a chinese Laser cutter, that we bought used few months ago from a local dude that had it on a barn with chickens and cows, the conditions were not the best to say the least, but the laser worked fine, and the price was fine!
Few months ago, we noticed that it lost alot of power and it wouldnt cut acrylic at all, i mean, even at 100% power, and going very slow, even 3mm acrylic is a PITA and takes too long!
since im the most tech savy dude in the company, i was the one in charge of trying to fix it, i tried googling this earth and all others to try and learn everything i could about lasers, everything seems to be fixed and aligned, we got new mirrors and focusing lens, etc, its a 60w CO2 tube.
for context it seems to be this one:

Same panel, same power source, same wattage, same bed size, etc.
Apparently its in TEM02 mode from what i could learn online, the beam coming out of the laser tube itself, before hitting any mirror, comes with 4 dots instead of one, in a “diamond” shame.
Basicly my question here is, if we buy a new tube, and only the tube, will it for sure fix the problem and the laser will be back at its feet working fine again? we have limited budget so we cant be spending that much money, and wanna be sure that it works well as soon as possible because we already have alot of delayed jobs because of it!
Can someone help me out? thank you in advance

Here’s some pics of it for context!

Yes, if the coolant is at about 20°C and you get anything other than TEM00, the tube is toast.

Unless you’re very unlucky and the PSU is also on its way out, replacing the tube is all you need to make it work properly again.

Thanks for the reply Tomatsu!

If its not asking too much, how can i know for sure that the PSU is not dead/dying?

thank you again

Welcome @Alexandre_Pinto

Unfortunately since the Laser Power Supply is very high voltage there is no safe and easy way to test it and thereby isolate it as part of the problem.

We typically diagnose a dead or damaged LPS by process of elimination.

Although it sounds like the tube is dead. I suggest we verify the tube is in TEM02 by posting a picture of a burn from the output of the tube.

Be safe and wear eye protection while working on the laser.

honestly i didnt knew until today we had to keep the water at 20ºC. i guess that was the deal because we never cared about but i remember putting my fingers on the water few times and it was very warm.

here’s a picture of the pattern that comes out of the tube before hitting any mirrors.

Yes that looks like a dead tube. Likely you overheated it since you were unaware of the temp specs.

Replace the tube and then you can tell if the LPS is also bad i.e. if you cannot fire up the tube. Likely it’s just the tube.

Its advisable to have a temp gauge and a way to shut down the laser in an overheat condition. Is there neither on that machine?

@HalfNormal or anyone else on this forum with this machine?

Since you really do not know how the unit was used, I agree that the best thing is to replace both your power supply and tube and you should get a long life. As for a chiller, I would suggest the CW-5000 which is an actual chiller and not just a cooler like the CW-3000 is. Here is an example;

And if buying a chiller and laser power supply and tube is too much, start with the tube and start using ice to chill the water, and realize that laser power supplies are also consumables, especially at the low end. The K40 Intro at the top of the page is your introduction to lots of information that is relevant to more than the K40 and will help you, including cooling options.