Ebay 50W laser problems

[Go-C Graphics]

I need some help and verification please.

I have a 50W ebay laser. It's the big blue one that's similar or the same as a SH-350.

I've been using it all weekend but tonight things went very VERY wrong. I was engraving a glass when all of a sudden the laser stopped engraving. About 5-10 sec later I heard the worst noise ever. I knew right off the bat the laser was arcing. I shut everything down with the emergency stop button. The FIRST thing I checked was the water pump and it's flowing perfectly fine. I have an active 1/4hp chiller that was working properly also maintaining the water at 21*C.

I've completely gone over the tube and I can't find a single break over the whole thing. I've checked the HV wire and it's completely fine also. Well I needed to verify that it was indeed arcing because I didn't actually see anything spark. After triple checking everything I powered everything up and I tested the laser using the pulse and sure enough the laser arching right under the HV side of the tube.

Now what do I do?

I can't find anything wrong with the laser tube. The ONLY thing I noticed was some condensation on the hoses because the water was too cold I guess.

After raising the temp alittle bit and waiting for the condensation to completely evaporate I decided to do another test and now I get NOTHING from the laser. Nothing when I push the pulse button and nothing when I push the test button on the power supply.

Are there any more checks I can do?
Is the tube and power supply gone?

I plan on call Marco in the morning but I figured I need to check here first.

Thanks for listening.

[Tech_Marco]

There are a couple things may leads the way of creating an arcing.
1) Returned wire (ground) wire on the negative side of the tube was not connected or got lose.
2) Positive wire got lose or if the contact pin is oxidized.
3) The tube is leaking so that no gas and no pressure inside of the inner tube. Electrons got no where to go but discharge itself through arcing.
4) The tube is dirty. If there is cover by a layer of dust, especially the charcoal dust from burning woods which is a good conductor from high voltage.

I used to have two of this machine and I had similar experience on one of that machine. The arcing was caused by three things: 1) dirty tube 2) poor grounding.
If you pay a little attention to the AC plunge, ShunHui used not connect any wire from the case to the 'Gnd' of the plunge. If so, you can make one up by connect the casing through a wire to the AC plunge.

If all above mentioned didn't help, may be you have a bad tube


Marco

[Go-C Graphics]

There are a couple things may leads the way of creating an arcing.
1) Returned wire (ground) wire on the negative side of the tube was not connected or got lose.
2) Positive wire got lose or if the contact pin is oxidized.
3) The tube is leaking so that no gas and no pressure inside of the inner tube. Electrons got no where to go but discharge itself through arcing.
4) The tube is dirty. If there is cover by a layer of dust, especially the charcoal dust from burning woods which is a good conductor from high voltage.

I used to have two of this machine and I had similar experience on one of that machine. The arcing was caused by three things: 1) dirty tube 2) poor grounding.
If you pay a little attention to the AC plunge, ShunHui used not connect any wire from the case to the 'Gnd' of the plunge. If so, you can make one up by connect the casing through a wire to the AC plunge.

If all above mentioned didn't help, may be you have a bad tube


Marco

Well I've done all the checks and I'm still not getting anything from the laser tube. No power, No sound........
I'm guessing it's just a bad tube and power supply now.

[Tech_Marco]

Check the water sensor first before making a conclusion. The sensor should be close contact while water is running through it. If no water is passing through the sensor, the sensor is in open contact and that will disable the laser power supply (LPSU)

Marco

[Tech_Marco]

Check the water sensor first before making a conclusion. The sensor should be close contact while water is running through it. If no water is passing through the sensor, the sensor is in open contact and that will disable the laser power supply (LPSU).

The water sensor built-in in most Shunhui machine is a bit bigger pressure need than most machine I ever seem. The default water pump is AC220V and it give less than 50% output when it is driven by AC110V. Double check it before spending money to buy "from us "


Marco