[SimonArthur]

Recently, during a moderately sized run of parts, my Artsign laser started losing power. Eventually it could barely scratch the surface of the acrylic I was working.

I don't get any greater power when using the "Laser Test" button.

So I would guess that the problem is with either the laser tube or with the high voltage power supply.

After reading a bit, I followed MacGyver's suggestion to check the resistance of the tube with the water flowing but the PS disconnected. The resistance was higher than my meter could measure.

So, how do I determine if I have a bad tube or a bad power supply? Can I get a replacement PS without having to wait weeks for one to arrive from China?

[MacGyver]

eBay has tons of replacement power supplies...

[lamicron]

Did you check the alignment? Check it first.

When you loose lase power probably is the tube loosing it. First you loose 10-20 % of the power and after a while, (weeks or maybe one or two months ) the tube will not lase any more.
Be careful of the tubes you found in Ebay , some people from the forum , had bad experiences with them , there is a importer in texas, Frank Fang, from Rabbit lasers, maybe he can help you.

[SimonArthur]

It's not the mirror alignment: the meter is barely registering any power and the sound made by the power supply when the laser is firing is much quieter.

The drop off in power happened over the course of only a couple hours.

Does the power output of the tube depend on its age or how much it has been used? Because tube has only been used for 8 hours of cutting or so.

[SimonArthur]

eBay has tons of replacement power supplies...

Do you think eBay item number 150205811563 would make a good replacement? It's a closed frame type as opposed to the current PS which is just a big circuit board inside the machine.

[MacGyver]

Does the power output of the tube depend on its age or how much it has been used? Because tube has only been used for 8 hours of cutting or so.

Very much so... most of the glass tubes are poorly sealed, causing an improper gas mix as time goes on. If the tube sits dormant for extended periods of time, it will often fail more quickly than if used every day.