Just went into my shop and tried to turn on my K 40. Nothing. There is power to the switches but the machine is dark. Is there a fuse in these machines?
There is a fuse in the very back, where the power cord goes in, accessible from outside the back of the machine I believe.
And another within the power supply.
Sounds basic, but if your machine has an emergency stop button, also make sure it’s not in the stop position. I’ve nudged it without noticing while working on upgrades etc and it certainly confused me for a sec.
I’m getting power to the power supply but the power stops there. I see the fuse in the power supply on the board. Any idea on the rating of the fuse.
If the fuse on the power supply is gone, it went for a reason. Mostly it´s the bridge rectifier blowing up located a inch further in on the power supply board, check if it looks blown.
Also check the cables to the buttons, broken buttons and switches are pretty common on these machines.
I can’t see any burned or discoloration on the board. The fuse looks blown and there is no continuity when checked with VOM. Is there any wiring diagrams available? A blown fuse on the board would indicate other problems. I’m new to this and I might want to upgrade the PS and controller boars. Where should I look for these?
@raykholo offers a drop-in controller replacement called @Cohesion3D (specifically, the mini bundle). I had great luck replacing mine, and Ray is very helpful. I don’t know about the PS.
Yep here’s the link for the k40 bundle: http://cohesion3d.com/cohesion3d-mini-laser-upgrade-bundle/
@donkjr knows a thing or two about these power supplies 
and you may want to check out his blog on the subject.
@bbowley2 schematics and such are avail on this blog. Look under LPS for info and lets continue from there.
Clearly your fuse is blown (common failure) and likely due to a blown MOSFET, Rectifier bridge, power diode or flyback.
WARNING: these supplies are dangerous and can kill you. I do not recommend repair unless you are a trained on troubleshooting high voltages.
@donkjr Given that these LPSs fail so commonly, do you have a recommendation for a drop-in replacement? Or is there no such thing? I tried digging through your blog for a link but none of the areas where you provide product links specify that you use them to drive the tube, only the other systems. Though I’m sure I just couldn’t find the right spot in the docs.
@Bob_Buechler there are links to supplies in the LPS sections:
… but I can’t really recommend any specific vendor. I suspect that light object is a good choice but frankly you can buy two of the standard types for the price of the LO one.
So I would just buy an ebay unit that is the same as in your machine. They often go on sale and I have seen them for as low as $65.
I even priced out the cost of repair and with shipping your better off to get a new one.
Once I find out why they fail we can figure out how to make them more reliable. Thats why I am asking for dead ones.
I found one for $80 on ebay. I’ll send you the bad one for your tests.
@bbowley2 that would be awesome and helpful for tests, where are you located.
Arizona
Ok I am in UTAH so not bad on shipping. Trying to find out how to get you electronic shipping label :). Never done that :(.
@bbowley2 can you send your address and LPS weight and size to this email? don.kleinschintz@hotmail.com
Shipping is not a problem. Do you know of any LaserWeb for Dummies. This software is incomprehensible to me. I need a beginners guide.
Do you need my address?
On laserweb what do you want to do first. We could do a video hangout?
Do hangouts on air, it will be recorded. It would help all the people!
@raykholo is hangouts on air something special?