Replacing power supply/laser tube question

[Jeffrey Michael Wilson]

Well since I can't narrow the problem down it looks like I'll get a new power supply and tube. I need my machine running Yesterday, can't even get communication from the folks who I bought it from (2 year warranty, only had it 6 months).... I've tried everything that was suggested here. So my question is, just how much do I have to worry about the red power cable, I see so much online about...don't touch it. If it's been shut down for days will the capacitors still hold a dangerous charge. (50 watt Chinese laser)... When I worked on TV's 35 years ago I just jumped everything to ground. Do I need to worry about this? Also any tips and tricks about installing. Does that huge ceramic resistor or whatever it is in power line open up, or is it solid?..... And just in case anyone has any other ideas here is my scenario. 50 watt Chinese laser, working fine one minute, the next no power to tube. Everything else works fine. Bypasses the flow switch with no change, disconnected line into power supply and hit test....nothing. No noise came from tube b4 it quit firing, no visible problems with tube or anything else for that matter, I tightened all connections, fuse in power supply is OK, The only online instructions for testing the power supply make no sense so if anyone has a suggestion about that, I'm listening eagerly. HELP.... Gotta get this thing working.

[Bill George]

A lot of suggestions a week or so ago when you first posted. The You Tube video #2 was very well done. You say you have done all the suggestions from the last postings? I guess its up to you now. Welcome to the world of eBay purchased Made in China equipment with no Warranty and no real Support.

No the PS should have zero voltage at this point (assuming its been unplugged) and the ceramic thing is more than likely a insulator.

[Jeffrey Michael Wilson]

Yeah, it'd be great if I could afford a $15000 American Made Machine, but I couldn't afford the one I got..... and you'd think ebay wouldn't give a seller 4 stars if they were totally bogus ("two year warranty and support")...... and the second video would be great IF it was my power supply, but mine does not have a red light that comes on to tell you it's defunct, or a power meter for that matter...and the first link seemed totally lame, taking a reading in the 3rd step or so when it wasn't even hooked up yet, and saying in that step to set it to 100%, when later when it is hooked up they say don't do that, set it low so you won't mess things up..... there were other things about that one I didn't get....but I'm no Master Electrician, just trying to get by here without spending more money I don't have. I was hoping to get the info here as to if it was more likely tube or power supply..Possibly something overlooked in previous conversations, maybe someone has different ideas.. I'm thinking I'll start with the power supply because there was no physical damage to tube, it's not very old, and I don't use it very much.... but then the power supply looks fine, fan runs, fuse is food, no visible burned our resistors or capacitors, and really not looking forward to putting in a new power supply and tube and still having it not work. I'd rather be persistent in my queries than spend money on something, and still have it not work.

[Dave Sheldrake]

Does that huge ceramic resistor or whatever it is in power line open up, or is it solid

ummm what huge resistor? the one supplied with machines is for checking the PSU function, it's not wired in with the tube is it?

[Bert Kemp]

My suggestion would be to buy your tube and power supply from Rabbit laser USA then you will have some support at least. You don't list your location.

[Jeffrey Michael Wilson]

I guess it's just a huge ceramic connector. Yeah, it's wired in the main power line coming from the power supply going to the tube. and the connections are clean, no evidence of arcing.

ummm what huge resistor? the one supplied with machines is for checking the PSU function, it's not wired in with the tube is it?

[Dave Sheldrake]

There is usually a white screw together connection on the HT side (RED) of the line that screws together, if anything other than that there may be a problem

[Jeffrey Michael Wilson]

No that is basically it.... and it looks good.

There is usually a white screw together connection on the HT side (RED) of the line that screws together, if anything other than that there may be a problem

[Ray Scott]

There is a white PLASTIC connector near the laser power supply. This is just to ensure a good connection for the RED wire. This RED wire is the HIGH VOLTAGE wire. The wire at other end of the laser tube is normally black. This black wire is the "return voltage wire. The intention is for the voltage to be "used up" across the laser tube.

Caution... If the the laser power supply is turned off, then the residual voltage isn't high enough to excite the tube, but this remaining charge on the power supply is high enough to give you a pretty good jolt... It could stop your pace maker.

A laser tube with a tiny leak could degrade over the course of two weeks. Using the laser tube increases gas temperature... Increases gas pressure... Shortens life further.

Does the laser tube work at all? Do you see any glow of light from the laser tube? Hey... Turn the room lights off.

easy way to test the power supply.. Caution... THIS IS CRAZY DANGEROUS...
1) unplug the power connector from the motion controller. We don't want it damaged.
2) disconnect the wires from the laser power supply to the tube.
3) use a wire alligator clip to connect the high voltage red wire to a piece of paper.
4) use an alligator clip to connector the "return voltage" wire to the piece of paper.
The alligator clips should be 1/2 inch apart. That's about 12mm.
5) jump out the safety items of the laser power supply .. (Connect the G to the WP)
6) set the laser power supply to full power (connect the "IN" to the 5vdc pin)
7) trigger the laser to fire (momentarily connect the G to the L pin)

The power supply should create an arc across the two alligator pins. This will burn the paper. If it doesn't arc and you did the test correctly .... The power supply is/was damaged. Doing this CRAZY test too much will damage the laser power supply. I prefer to add a very large resistor into the circuit. 100Joules... 100,000 ohms. At the proper resistance.. The circuit should have less than 30mA current, but still has a massive amount of voltage.

if the laser power supply works... Then the laser tube can be connected and tested. If you get nothing from the tube with the bypass tests, then the tube is damaged.

I believe that your best bet is to send the power supply to a laser specialist and have it tested. If it is good, then pay for it to be shipped back. If the power supply is tested as bad, then you have found the problem. ... But the power supply could always get damaged during shipping.

Ray Scott

[Jeffrey Michael Wilson]

Thanks Ray, good info. Do you know any laser specialists who could test it.... My wife doesn't want me to do ,"crazy dangerous"......So can I ground out the remaining charge in the power supply. Some folks say it goes to pretty much zero after time....
thanks again

[Bill George]

My Chinese laser had a tool kit with the green ceramic resistor Dave referred to, and my kit also included the jumper block Ray wants you to make. My Chinese laser also had a mounted mA meter. All of the above was in that 2nd video and how to use to correctly and safely check your power supply.

[Jeffrey Michael Wilson]

Mine had no tool kit, no resistor and no mA meter, would have been nice though. AND no red light on power supply.

[Bert Kemp]

Jeff you have no location so we can't tell you were to send your power supply. I'm pretty sure Ray could test it for you, he's in Ohio. You might want to check with a local tv repair shop( do the still exist? LOL )) or electrician. Maybe an electronic shop could do it.

[Jeffrey Michael Wilson]

Hi Bert, I live in Oregon.... TV repair shop.... hmm? There used to be a guy in Eugene, I'll see if he's still there. Thanks.