I have a question …
I have a 50w co2 power supply that sits… and I am thinking to fit a 60w laser tube (1000mm long) …The prizes is really low at this moment in Germany… is it possible ? or I damage the psu?
Seeing as how those k40 psu like to pop with the slightest over current draw, I would think it is better to have a psu that can handle a much larger wattage.
Unfortunately you need a 60W to get full power and not kill the supply. I think you can get a 60-80 watt supply.
Don, these don’t have to be fitted to the tube size right? So I could have a 100w PSU run a 60w tube?
@raykholo you have a point…I blew mine in the first few hours(40w stock)…But… I don’t know if for example change some parts to the PSU can make it more durable… maybe @donkjr enlighten this.
@donkjr you are fast 
The voltage requirements goes up with the length, so does the power so It does matter if it’s undersized.
For a larger than needed supply.
I am not sure if too high a voltage will matter or if you can turn it down. Never had a larger supply.
@Kostas_Filosofou as you may know I am collecting dead supplies to analyze failures and see if we can improve them.
So far I suspect that there are 3 types of failures: flyback, bridge rectifier and power transistors. Flyback may be the most frequent.