LaserUser.com Forum (formerly RDWorksLab)

Without seeing or knowing about the specific Laser if you are getting a Beam that doesn't switch on when asked and is stuck on the 'HV part of the Power Supply' itself is unlikely to be the culprit.

I would be looking to either the output stage (less likely case) of the controller which is used to genertate a logic level (generally 0-5VDC) which is then sent to the input side of the Power Supply. If you know of someone with an Oscilloscope this is easy and safe to test and eliminate. If this output is locked high or low (depending on the logic the PS needs) then the PS will stay locked on.

Or what is more likely is the input switching side of the Power supply has a blown component. If you have a tame Electronics nerd at hand this is also fairly easy and safe to test by simply disconnecting the HV Transformer (this almost certainly will be fine so keep it) and looking at the signal that would be going into the HV. Worst case you are only dealing with mains voltages at this point. What you will be looking for is a component that has failed to a short circuit which happens or potentially that shorted component has taken out others. Chances are if you lift the lid on the power supply you will see where the magic smoke was released.

Lift the lid on you PS but be careful of touching a Capacitor they bite and can hold charge for quite a while

My PS with the lid off.

Hi Jeffrey, I'm guessing the 60 in HY T 60 relates to the wattage. My tube is 50W, would this unit be ok?

Tim Mellor wrote: Fri May 31, 2019 Without seeing or knowing about the specific Laser if you are getting a Beam that doesn't switch on when asked and is stuck on the 'HV part of the Power Supply' itself is unlikely to be the culprit.

Just to be clear for those who are new to all of this, what Tim is referring to is the stuff INSIDE the HV Power Supply. Within that box, (which he pictured), there's some low-voltage circuitry, and then a big transformer (the big white thing at the right of his photo) that turns mains (line) voltage into several thousand volts.

One could fix it (if you're qualified), or one could just replace the whole "HV PS" box. Personally, I'm qualified, but lazy - I'd just replace the whole thing.

Regards,

-Jeff

John Hulme wrote: Sat Jun 01, 2019 Hi Jeffrey, I'm guessing the 60 in HY T 60 relates to the wattage. My tube is 50W, would this unit be ok?

Higher wattage supplies are fine. Lower wattage supplies are not.
One might have problems if you go with TOO high a wattage (e.g. a 100W supply for a 50W tube) because you might have problems programming a low-enough output for etching thin materials (e.g. paper). I'm not sure about this.

Thanks Jeff, I will order the new power supply next week and let you know what happens. Thanks to everyone for your help.

Not so much 'Qualified' as competent when playing with electrical things is important. I have worked with a lot of Qualified people be they Engineers or Electricians over the years and some I wouldn't trust to swap a light bulb let alone design one in the case of some Engineers

Basic mains voltage is plenty to kill you and surprisingly the HV side of a current regulated supply like these smaller Lasers run is in some ways safer regards Electrocution risk. It is the Current generated across the heart that is dangerous so unregulated mains voltages is a higher risk.

Just consider that when poking around replacing power supplies and doing mains side wiring lest your smoke come out

Some HV Fun, the Black cover right at the back is my little Laser to keep it sort of on topic This is 12kV @ 30mA

https://youtu.be/VCIXY-z27EM

Hi, before purchasing the new power unit I checked the wiring diagram. The connections are relatively straight forward, however, the unit installed now (the blue image) has a connection for the negative wire from the laser tube. The upgraded unit (the black image) does not have this connection. Where do I connect the negative wire from the tube on the upgraded unit (HY-T-60)? I hope the image has appeared!

many have a separate lead hard wired into the pwr supply - do you have a pic of the whole thing (HY-T-60).
I don't know the answer to your question but I will bet Jeffery does.

Hello again Pete, I think I have just answered my own question. I have found some other images of the HY-T-60, you were right there is a separate wire hard wired into the unit. Thank you.

Success, I have installed the new power supply, problem solved. Thanks for all your help and advice.