Laser power supply!

[amd]

I got my new laser machine one month ago and I was starting to cut some acrylic jobs then the laser power supply gone (suddenly)
Every thing was stable and good within the machine while cutting and laser beam stopped suddenly while it moves normal
So, I checked the laser tube and the power supply and I found power supply “fuse” has been melted!
I change it and once I connected to the power source the fuse melt it again.

I contact the machine supplier and he told me that they will send another power supply and they don't know yet from where that happened! and they ask me to return the old one (power supply) back to check may they know the reason

Any input from you about the laser power supply problems will be great. Because, I am worry a little to install the new one tell I know what was the reason to avoid the same problem with the new one

My machine is SUNIC machine (250 cm X 130 cm) 100 watts China made
The power supply name JYMD and I tried to contact them but their web site not working properly

Note: I used the machine about 5 hours in total only!

Thanks in advance for your inputs

[amd]

The final manufacturer reply about this problem was like that:

The reason which could happened in the power supply one or both of the following reasons:
1. Laser tube metal pole not isolated as should be
2. The machine and power supply not connected 100% to the earthing

I have good earthing connector in my workshop and I am sure from it. So, the only reason will be the laser tube isolation!!

Please, if any one give me an idea to be sure from the isolation of the HT line which is connected to the laser tube it will be very helpful

Thanks in advance

[MacGyver]

Check the resistance from tube contact to contact (not connected to power supply) while coolant is running through it. If you're less than many megaohms, the tube is hosed.

[amd]

Thanks MacGyver for your reply...
What about the HT/HV cable isolation .I mean the cable itself
What I have is the HV cable “electrically soldering” with the tube pole (anode) and has been covered by rubber tube.
Is this enough?

[MacGyver]

Unless the wire itself is sparking, you're concerned about the tube having a low resistance. A leak in the tube will show up as a low resistance (hence the test being run while coolant is running through it).

[amd]

Forsure I'll do it (the tube test). I'll check the tube resistance while coolant running through it.
But what I would like (also), your help to be sure 100% that the HV cable not sparking
What kind of isolation should I use?
By the way, the water level is in the same level and that also, another indicator to say no coolant leak within the tube

[SkipW]

amd,

Mine has some sort of rubber strip that surrounds the tube holding saddle and clamp, and the HV power wires just use alligator clips on both ends that have a rubber boot over them.

Skip

[amd]

Skip,

Many thanks for picture and clarification.
How many KV your power supply produce or How many watts your laser tube?
Mine is 40 KV (max.). Is that making any different or I may use just simple alligator clips on both ends instead of soldering?
I'll change mine at once to clips if it safe from sparking

[SkipW]

Hi amd,

My laser is 80w. I'm not sure of the specs on the power supply. I tried to find the info in the owners manual but it's not there.

Skip

[amd]

Please see attached, an extract paper from manuafutrer manual about laser tube installation. They stress to be welded.
Because of that I am wondering to use only alligator clips!

[amd]

Skip,
Don't bother yourself about the HV KV. The watts amount of the tube is enough for me.
It seems to me my manufacturer worry about the cable isolation more than enough
I'll check the laser tube resistance while coolant go through it as MacGyver said
Then change to alligator clips for both ends, it will better and easy for me in the future laser tube changes. Especially I don't like the manufacturer soldering way and its shape

Thanks a lot for both of you

[SkipW]

amd,

I don't know why some manufacturers say to weld, and some say don't weld, but the clips work great for me. I can't say if those are special HV clips or just regular ones. My laser is from WK Laser.

This laser tube manufacturer seems to be saying do not weld. They say just wrap the wires and tape them. Read item number 6 here.

regards,
Skip