[dendor]

I have LC1490 power 120W from G-Weike, bougth in september 2012.
A few months ago it stopped halfway cut on paper, but continued moving until the end of the work.
The head continued to move and process the job but the laser wasn't firing. The Ammeter display on the front of the machine doesn't read any amps.
I checked the power supply and laser tube and found that the fan is not working, but the lights go well when I press the red button.
The fan was stuck. I cleaned and lubricated fan. Now the fan works fine.
The laser tube glass looks well (not signt of broken), but do not have red ligth when I press the Laser button.
Electric resistance testing method: - the current should show over 30ma (like in video on youtube - Laser tube problem or Laser powersupply problem).
I was convinced that was broken laser tube. I ordered a new tube as well as a new source.
I changed the first source and "SURPRISE": - old laser tube firing (the new one is still sealed in the box).
Old laser tube is Reci W4 - 120W and new power supply is DY -13.
But i have another problem: laser firing continuously.
I pressed buttons: Stop, Datum, Test and laser don't stop firing.
I clicked "Start" button and lasers began last work of memory but cut continuously (even when they only had to move).
Finished work, stopped moving, but the laser continues to firing.
I cut the power because it could cause a fire.
I'm afraid to put new tube so as not to spoil it.
I think it is still good old tube.
Has anyone had this problem?
How to solve it?

[buddydog]

To bad you didn't post this in general laser forum. But yes I have had this problem and it is of course due to a problem with the supply. First I don't have your exact set up but I think the general directions will still apply. Simply there are a couple of inputs to your power supply that tell it to "fire" the beam. On my setup the signal to "fire" is a "ground or "-". Any time a ground or minus is applied to the signal inputs the power supply fires the laser for as long as the ground is applied. Most likely one of those inputs has a "permanent ground" on it (bad switch, pinched wire etc). I would start your troubleshooting by disconnecting the plug of wires that goes from the power supply to the software control board. That eliminates one possible "firing" source. The control board turns the laser on and off as it also controls the x y axis, so disconnecting that source tells you if it is causing the problem. Ok other than some safety switches (which would only prevent firing, not cause it) you have one source of ground left and that is the "test" or alignment switch. Once you disconnect that the problem should go away if the switch itself is the cause. And finally the last possible problem is in the power supply itself. If the sensing circuitry in the supply internally shorts then even with everything disconnected (Except the safety switches, water, door etc. They have to remain in the circuit or they will mask the real problem by possibly keeping the laser "off") the laser will still fire and troubleshooting or replacing the supply (again in your case) is the answer.

I will do a detailed explanation hopefully in a couple of days in my thread "troubleshooting the K40" . On mine a resistor called a "pull up" resistor had not been soldered from the factory in the supply and that was making the supply think it had a ground on it's input and so it stayed "on". Mine was actually intermittent as the resistor was not actually bad but instead one lead was resting against the hole where it was supposed to be soldered and so it would work sometimes and sometimes not! Very frustrating and actually very dangerous. I am now very careful to never assume the laser is "off'" and if working inside the cabinet while the power is applied, I put a piece of aluminum in the path where it enters the cabinet "just in case". The factory sent me a new supply and after fixing the problem by replacing the supply, I took the cover off the old one and I actually had predicted exactly what the problem would be and sure enough it was there. These folks don't supply schematics for these things and so these devices live in the murky world of highly technical device that the home or consumer user must troubleshoot himself with basically no help. Their answer is to have plug in "black boxes" and so no component level troubleshooting. In my post I will try to "reverse engineer at least the simple "control input" portion of the supply I have. It should be very close to all the other supplies and at least a little more information out there won't hurt.

Be very careful!!