40W tube on 60W power supply?

[Gabriel Voicu]

Hello! Long time reader but first post.
Recently, my 60W laser tube started to fail. Well, after 6 years it is still have power, but the total reflector mirror burned in the middle and the beam is like a circle now.
Because i can't afford a 60W (1200 mm length, 55mm dia) tube right now (it is nearly 700E in my country) i want to buy a much cheaper 40W (850mm length, 50 mm diametrer) tube for a while.
It will work on my old 60W power supply? The power supply is a cheap one based on how it looks.
I found different opinion arount the web. I asked some chinese sellers from aliexpress, some says is ok if i not exceed the mAmps, some says definitely no.
Maybe someone around here tried this and can give a better advice?

Thank you in advance!

PS: sorry if i made mistakes, i'm not a native english speaker

[Mike Null]

Gabriel

Welcome to Sawmill Creek. I'm sure somebody will be able to give you some good advice. Too bad the 60 is so expensive.

[Dave Sheldrake]

If it's a DC tube then yes and no depending. Some multi purpose PSU's will run both a 40 and a 60 but some will just kill the 40 as the current may not be user adjustable (the voltage on the 60 is a little higher so will shorten the life of a 40 watt tube anyways)

I'd advise against it to be honest unless you know the full spec of the PSU and the tube you will be fitting

best wishes

Dave

[Gabriel Voicu]

Thanks for the answers,

Yes, the tube will be a cheap CO2 sealed glass.
The PSU don't have any stickers on it, but it look like this: http://thumbs1.ebaystatic.com/d/l225/m/mhKY9-HYsX2cXgPvYxEM_HQ.jpg
Anyway, it doesn't have any knobs or anything on it.

[David Somers]

Gabriel,

Dave Sheldrake can confirm this. But if there is an adjustment on the PSU it is not likely to be an obvious thing like a knob. It is more likely to be a hidden pot. That would be a relatively small hole in the side of the case of the PSU with a flathead set screw, often called a pot which is short for potentiometer, recessed inside it. Turning the screw adjusts the setting, which you would verify with a meter on the output leads. You want directions with photos on how to hook up and measure this though since you are fussing with some reallllllly high voltage stuff depending on the wires you are near. I have a set of instructions on this from Instructables.com that covers the process with photos. But I have not personally done this so I can't attest to how well done the instructions are. The link to that is http://www.instructables.com/id/How-to-test-and-set-a-Chinese-China-made-CO2-Laser/. Have someone with a clue verify this before you do anything please. I would hate to see my lights go dim and flicker here in Seattle and think....Ooooops. There goes Gabriel!. Seriously.....

Dave

[Dave Sheldrake]

correct Dave, my only concern would be the higher voltage as well

cheers

Dave

[David Somers]

By the way Gabriel, You will need to set up an account on instructables.com to look at that. It is free and quick to setup. And you can control what they send you pretty well. It is both useful, interesting, and full of fluff stuff. A real mix. But it does have good stuff on it.

Hope that helps. And again, seriously, we are talking high voltage danger here. Take great care.

Dave

[Gabriel Voicu]

Thank you, everyone for your answers.
I intended to install a smaller tube without any modifications. I found a supplier around here that said they can send an engineer to addapt the power supply, but they will charge for this and for the tube installation. But the only reason to install a 40W tube was the money.
Maybe i can adjust my PSU by myself, i am not a total noob, but i would never use a cheap meter to measure the currents, and a good one will cost anyway.
Finally, the supplier that delivered my machine 6 years ago made me a good offer and i'm gonna buy a 60W tube from them. The first one lasted 6 years, so maybe they have some good ones now too.