So I apologize in advance if this has already been talked about. I tried looking and found a few topics but didn’t see the answers I was looking for.
I have an Omtech 100W laser and was in the middle of a burn when the laser stopped firing and the laser head continued to run as if there were no issues. (I could get the laser to run the burn again and everything would move but the laser would still not fire)
I looked at the LPS and the screen would not come on. I unplugged the controller connector and hit the test button and it would not fire. I checked voltage and was getting 120V at the LPS. I checked all of my interlocks (e-stop, lid, and water) and everything looked good.
So I ordered a new LPS and plugged it in and still could not get the laser to fire. Having a bad LPS out of the box is not impossible but highly unlikely. The new LPS screen does not turn on and when I try the test nothing happens.
Any input on what I should be looking at would be greatly appreciated.
My machine has a keylock switch in the Line side of the AC input to the HV supply that failed open: the internal contacts would sometimes not close. Assuming your machine has a similar switch, that could be the problem.
Measure the AC voltage across the HV power supply’s AC terminals, rather than from either terminal to frame / safety / earth ground. If your machine has a similar keyloc switch miswired in the Neutral wire of the AC supply, bothAC terminals on the power supply will be at Line voltage with respect to frame ground with the switch contacts open.
If that’s not it, other possibilities raise their ugly heads …
I just checked again. I am getting 120V at the connector (which is why I was thinking its a bad LPS) but the new LPS I just got yesterday is doing the same thing. I also unplugged the connector again (the 6 pin connector) and hit the test button again and nothing. Are there any other inputs (controller, WP, ect) that the LPS needs to see to have the screen turn on? Or once it is seeing power should it light up?
I pulled the connector out. Did a slight pull test and made sure the screws were tight. Plugged the connector back in and still nothing.
So as long as the LPS is getting power (120V) the screen should at least light up correct? Which I agree with you that it looks like the LPS is bad. Its just hard to believe that a new one out of the box is bad also (I know its not impossible… Just usually unlikely)
On mine, you have to have a main switch on as that supplies the whole machine. On mine it takes both switches to get power to the lps.
I used to fix other computers… One time I was tearing out my hair, after three cables, the fourth finally worked. These cables cost about $5000 each and chained up the disk drives. I’ve seen them make them, back in Boston, by hand and their is even a computer they stick both ends in and it checks it… Have no idea why or how I could get three new bad cables.
I’m still thinking there’s something wrong in the AC wiring upstream of the HV power supply.
Being exceedingly careful, can you unplug the AC connector from the power supply and measure the voltage between the two AC terminals inside where the supply has its pins? This may be a job for a pair of alligator test leads, rather than hand-held probes.
IIRC a while ago somebody reported problems with a similar connector. Apparently it had all the right parts and measured correctly from the outside, but had a broken pin inside making intermittent connection with the power supply terminal.
I’ve heard some horror stories about wiring. If it’s bad it unlikely that it rewired itself mid job. I’ve heard of a few where they measured one side to ground. Dismissed the thought as he states it worked then quit and the machine was still operating mechanically.
I follow where you’re coming from, nevertheless. Especially with the same type of failure as the first. But it’s hard to tell when you have only a light and a test button.
I think he lost something, I’m also rather disappointed that he likely got a bad power supply.
It sounds like a hardware failure and I’d pick the lps since it has never worked.
He needs to contact the vendor and ask them, they just might replace it.
Alright. So I returned my LPS and got a new one. Installed it and… Nothing This time I pulled the 3 pin connector and put the wires into the connector that was sent with the LPS. I also tried just having that plugged in and hit the test button. Still no luck. The screen will not turn on.
Would the LPS not turn on it there is a problem with my laser tube?
Its odd that there would be a wiring issue that would pop up in the middle of a burn and only effect the laser side of things. Not the XYZ, Air assist, main controller.
Does the machine plug into a 240 VAC outlet? That would be the only case where both wires would measure 120 VAC to the machine frame = “ground”. Measured between the two wires, as I suggested, it would measure 240 VAC.
If it’s plugged into a 120 VAC outlet, then the voltage between the two wires should be 120 VAC.
However, measured from each wire to the frame = “ground”:
One wire should be at 120 VAC
The other wire should be (close to) 0 VAC
Which those situations matches the measurement you made?
In summary, the default “home” electrical service has three incoming wires:
Neutral = 0 VAC
120 VAC relative to Neutral
120 VAC relative to Neutral
The Neutral wire is bonded to a real “ground rod” pounded into the earth just outside the building foundation. In some cases, the water inlet pipe serves as that Earth ground.
The two 120 VAC wires are 180° out of phase, so that the voltage between them is 240 VAC.
Heavy loads like clothes dryers and heat pumps run from the 240 VAC wires, with a third wire bonded to Neutral and Earth.
Ordinary loads like lighting, small appliances, PCs, and suchlike run from either of the two 120 VAC wires to Neutral.
happens…
This time I pulled the 3 pin connector and put the wires into the connector that was sent with the LPS. I also tried just having that plugged in and hit the test button. Still no luck. The screen will not turn on.