20W 40W 60W PWM CO2 Laser Power Supply Failure?

RexJaguarius
Posts: 7
Joined: Thu Feb 20, 2014 6:01 am

20W 40W 60W PWM CO2 Laser Power Supply Failure?

Postby RexJaguarius » Thu Sep 04, 2014 9:27 am

Hi, I was wondering if anyone can help me. I purchased a "20W 40W 60W PWM CO2 Laser Power Supply" back in march, and its been installed since may. The unit has a single test button, which is supposed to fire the laser regardless of the hookups. I was using my laser recently, having replaced the laser tube about a week before because of low power/arcing, and after working very well for a few days suddenly I started having a jittery laser, clocking in at about 6ma max. Changing the potentiometer no longer worked, and even firing the laser with the test button on the supply still gave the low power slightly flickery tube. The laser tube is humming as if it is turning on and off rapidly. Having only bought this power supply recently I am really hoping it hasn't blown for some reason.

I removed the supply from the unit and hooked up a spare tube and even using the test button, the laser doesn't seem to want to fire. The fan is on, and if the water pump jumper is off I get a red light but I can't seem to get the laser to work.

Can anyone offer advice on testing or possible repair? Is there a procedure for pressing the test button that would allow me to get an indicator light or something? i opened the cover and there doesn't seem to be any obvious burns and the fuse is good.


Image

Thank you!

Tech_Marco
Posts: 4333
Joined: Mon Jun 15, 2009 3:00 pm

Re: 20W 40W 60W PWM CO2 Laser Power Supply Failure?

Postby Tech_Marco » Thu Sep 04, 2014 10:22 am

Easy to fix it. Just tap the two wires together and bypass the AC110v/220V switch will bring you back to the business

The cause was the switch. Somehow a tech only use one pole,one throw for the connection. He should use two so over current damged the switch


Marco

RexJaguarius
Posts: 7
Joined: Thu Feb 20, 2014 6:01 am

Re: 20W 40W 60W PWM CO2 Laser Power Supply Failure?

Postby RexJaguarius » Thu Sep 04, 2014 10:43 am

Tech_Marco wrote:Easy to fix it. Just tap the two wires together and bypass the AC110v/220V switch will bring you back to the business

The cause was the switch. Somehow a tech only use one pole,one throw for the connection. He should use two so over current damged the switch

Marco


Excellent I will try that right now!

Tech_Marco
Posts: 4333
Joined: Mon Jun 15, 2009 3:00 pm

Re: 20W 40W 60W PWM CO2 Laser Power Supply Failure?

Postby Tech_Marco » Thu Sep 04, 2014 10:49 am

Let me know asap. Im waiting to see the result while I'm taking a coffee break in Dennis

Remember, tap the two RED wires only, nothing else


Marco

Tech_Marco
Posts: 4333
Joined: Mon Jun 15, 2009 3:00 pm

Re: 20W 40W 60W PWM CO2 Laser Power Supply Failure?

Postby Tech_Marco » Thu Sep 04, 2014 11:48 am

Here is how you test:
1) Ground "WP" to "G" where "G" or "Gnd" means ground
2) Tap "+5V" to the "In"
3) Once "TL" contact the "G", it will fire in full power!

Give it a try. BTW, I'm assuming you're running at AC110V, aren't you?

FYI, there is a thermistor (green color) next to the Red wires. It could be break also. If so, you can bypass it as it is useless but trouble. For all our new design, we eliminate that resistor as it has nothing to do with the PSU


Marco

RexJaguarius
Posts: 7
Joined: Thu Feb 20, 2014 6:01 am

Re: 20W 40W 60W PWM CO2 Laser Power Supply Failure?

Postby RexJaguarius » Thu Sep 04, 2014 11:55 am

Thanks so much for your help Marco. It seems that the problem was the 110v/220v switch, and yes you are correct that i am using 110v. With the switch out of play the laser comes on at full power when L is grounded. The test button doesn't seem to be working, but that's not important as I have one wired in from my machine.

I'll report if anything changes but I think I am good to go now. Thanks again!

Tech_Marco wrote:Here is how you test:
1) Ground "WP" to "G" where "G" or "Gnd" means ground
2) Tap "+5V" to the "In"
3) Once "TL" contact the "G", it will fire in full power!

Give it a try. BTW, I'm assuming you're running at AC110V, aren't you?

FYI, there is a thermistor (green color) next to the Red wires. It could be break also. If so, you can bypass it as it is useless but trouble. For all our new design, we eliminate that resistor as it has nothing to do with the PSU


Marco

Tech_Marco
Posts: 4333
Joined: Mon Jun 15, 2009 3:00 pm

Re: 20W 40W 60W PWM CO2 Laser Power Supply Failure?

Postby Tech_Marco » Thu Sep 04, 2014 11:59 am

The Test button is another minor issue. It works great on AC220V but sometimes it may not work on AC110V. I guessed the engineer forgot about the AC drop from 220V to 110V and causing the triggering circuit not being able to get enough 'juice' to fire it. True that it has nothing to do with the regular usage when the PSU installed in machine. FYI, we did fix the problem for the latest design PSU.

By the way, sorry for the trouble and taken your time to fix the PSU. I owed you a favor!


Marco


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