View Full Version : power supply, cable or tube fault?

Mike Lysov
05-17-2017, 5:24 AM
Hi guys,

I am alucky one. Just recently repaired my laser with a Synrad tube and today the other one with two GCI tubes(each 140W) stopped working properly.

Since this laser has two tubes it has two power supplies so each tube is powered by its own power supply(HVPS). There are two LEDs on each HVPS and it seems when HVPSs are working properly both LEDS on each are OFF. If there is anything wrong one LEDs turns red. There is also reset button on each HVPS. When the LED is red you push it and it resets and the LED goes off.

Now back to the problem. When I power my laser from a power outlet both HVPSs seems to be in a normal state(no LEDs on) but when I fire the laser there is a a single shortening sound and one HVPS has its LED red and the tube connected to it is not firing at all. Pressing reset on this HVPS turns that LED off. However when I fire it all goes the same(LED is red and not firing). So basically one tube is firing since it is running from its own power supply and one is not.

How did I get to that sad point:

1)My laser was working as usual today morning(both tubes firing, not faults at each HVPS) but alignment was off.
So I decided trying to align my laser at its best and the first thing you need to do is to align both beans together. To do it you need to disconnect one tube from power or cover it with something. Covering can lead to some residue left on its coupler so for the last a couple of years I prefer to disconnect a power cable from a relevant power supply. I have been doing this type of alignment a lot of times before so I do not believe that this constant cable connection/disconnecting while machine is powered could cause what I am facing now.

2) My other tube seems to produce a double burn mark(or it is just looks like it does). That tube is connected to this "faulty" power supply. This split beam from that tube creates a lot of problems(heating head, impossible to cut through at some far points). So it was the reason I started doing realignment today morning. I checked connection to that tube on both ends and both wires seemed to be quite loose. I cleaned all connection on the coupler side and tightened the wire on this side of the tube and moved to the back(where the wire is under ceramic cover). This connector also locked loose and also it seemed not to be very well welded to the wire under a thick insulation. I remover the wire, removed one layer of insulation and check that the connector is welded well, put an insulation tape on top, cleaned all contacts with an alcohol and connected it back to the tube.

That's when it all started with this tube HVPS.

No I need t understand what's is wrong. The wire for the tube that I have removed the insulation from seems to be ok(resistance is steady 0) but something is wrong as firing the tube seems to do something with it HVPS.

Ordering a new HVPS is my last resort as mt MFG wants almost USD $1300 for it. Plus they will be heaps for shipping, duties and taxes that will make this HVPS almost made of gold comparing to the similar ones sold on eBay for 150W DC tubes. I would go with the cheap one from eBay but I am not sure I can use another brand power supply as it will be working with the first HVPS alongside or may be there will be other problems.

I contacted support for my laser but so far they are not big of a help and there are some language problems(they are from Taiwan) They may be hlp me eventually but I know it will take ages.

Since it is two tube machine I can still use it but there is a huge drop in cutting speed and edges are too much charred because of it.

I have attached picture where wires are connected to each tube. The one with blue insulation is the one i opened to see if there is a loose wire. I do not run my laser without covering caps. I have taken the of just to take a picture.

Bill George
05-17-2017, 8:25 AM
So the blue lead is your ground lead for the tubes? And instead of disconnecting the HVPS input to disable a tube you removed the ground wire. I also do see both tubes connected together but no actual connection to ground?
I can see all kinds of issues, with that, such as causing internal arcing inside the PS as the HV tries to find a ground. Removing each PS and looking for internal arcing or HV carbon tracks is what I would do first.

Mike Lysov
05-17-2017, 10:13 PM
Thank you Bill, is ground connection located at the front of the tube or at the back of it? It is just not clear if you are asking about the wire with blue insulation tape(2nd picture) or two blue wires connected each to the front of each tube(3rd picture)?

If it is I actually have not mended these wires apart from tightening nuts where they are connected to the tube. Then after this problem started with one of the HVPS I removed the wire from one tube cleaned contacts and put it back. I guess I am better check that wire with a multi meter too.

Just a couple of questions, when you say I need to check power supply for HV cabron tracks, what exactly I need to look at/for?
If I get a relevant HVPS from ebay do you think two different HVPS will be ok? I mean one of my HVPS is working so there is no need to replace it. O it will be one original one and one from another MFG with the same or slightly different power rating.

Bill George
05-17-2017, 10:34 PM
The HV leads are the heavy insulated ones, one to each tube from its respective HVPS.
So I was asuming the thin blue wires were the tube grounds. Each HVPS should have a ground
wire. Somehow I got the impression you disconnected either the HV lead or ground wire
so you just have just one tube powered for your alinement procedure? Perhaps I was reading wrong.

Mike Lysov
05-17-2017, 10:58 PM
No Bill, I did not do that.

When I need to align beams to combine then I just take a power cord from a relevant to this tube HVPS. Then only the other tube that is powered from its own HVPS is firing. So both(negative and positive) wires on each tube are always connected to the tubes and to their HVPS when my laser is powered . My laser machine distributor guy recommended it as an alternative to blocking one beam on it way to combiner. I have done it this way at least three times in the last two years. I did not have any problems with HVPSs doing it this way before.

Mike Lysov
05-19-2017, 4:25 AM
I think it is better to use some notations for each tube and the HVPSs as it may be hard to understand which one I am talking about. I will use the second image from my initial post above as a reference. The tube on the left will be called the tube "A" and its HVPS will be the HVPS "A". The tube on the right will be called the tube "B" and its HVPS will be the HVPS "B".

The tube "A" fires and its power supply does not show any problems. The tube "B" does not fire, something makes a single crackling sound and the HVPS "B" goes into a mode required resetting. That's how it all started.

Now I am trying to dig further into the problem.

I have moved a positive cable of the tube "B" away from any other wires and other electrical parts inside my machine, insulated its end(removed my blue insulation and used black thick one). Nothing changed apartfrom that I cannot hear the crackling sound.

Then I swapped both wires connections for the tubes trying to run the tube A from the HVPS "B" and the tube B from the HVPS "A".
The tube "A" fires even being connected to the HVPS B, but the tube "B" which is now connected to the HVPS A does not fire. Neither the HVPS "A" nor the HVPS "B" go in a resetting mode.

From this step it seems it is not HVPSs problem because it has proved that the HVPS that was used to power the tube B now works perfectly with the tube "A".

For the last step I swapped actual wires(both positive and the ground) for each tube. Now wires from the tube B are used on the tube A and the wires from the tube A are used with the tube B. The tube A still fires but the tube B does not. So both pairs of wires seem to be ok.

Is there any way to tell/test if the tube is ok? There are no visible cracks on the tube B so I do not believe there is no gas left in it. What else can be wrong with the tube B that does not fire even with power coming to it?
The tube B could be a problem for a long time as there was some strange heating at the laser head and very bad cutting at least in half of the working area.
I also believe this tube had its beam split in two making two burn marks instead of one. Please see attached image.
That may be a problem that caused the head heating.

Dave Sheldrake
05-24-2017, 9:14 PM
Just remembered, Millenium Lasers over here can refil GSI tubes Mike, be careful, those red dots from memory are the polarisation alignment marks

Mike Lysov
05-26-2017, 7:14 AM
Thanks again Dave for all your help. I have just sent them an email.
I hope they can do it as there seems to be nobody in the whole word that you can find on google searching for GSI(or JkLaser) tube repair/refill.

Chinese sellers advertising GSI tubes for sale are lying. They are not selling GSI tubes, they are selling their own tubes calling them GSI.
I submitted a request on Alibaba for my model and specified that I need GSI tube, 7 knocked already and none of them offered me the tube I need.