Well, I’ve lost power again. This time everything works except the laser won’t fire.
I’m at a loss as far as trouble shooting. The machine turns on and the laser head will follow svg files but just won’t fire. Last time my power supply was bad. I was able to trace incoming power to the power supply. The fuse on the board was blown. Replaced the PSB but this time everything works except the laser won’t fire.
Sorry we need a lot more info than this as many things could cause the laser not to fire.
With the power on …
- Is the LED down on the LPS on or off
- Does it fire if you push the “test” button down on the LPS?
The red led is on.
It doesn’t fire when I push the test button on the LPS.
oops, the green led is on.
Impossible to remember, but does your machine have a dial to set the laser power? If so, is it turned up? Any wiring problems, or bad potentiometer?
The “TEST” (or “TEXT”) button on the power supply will turn the laser on, but only if the “IN” (Intensity) input is active. Sometimes bad wiring, or a bad pot, can fool you.
Post picture showing the LPS input connectors.
Insure as @Nate_Caine suggests that the pot is all the way up and try “test” again.
If that does not fire you measure “IN” relative to grd with a DVM and it should be close to 5VDC.
No pot. Digital buttons for increase or decrease.
Schematic for tracing voltages?
Measure "IN " with respect to gnd, with the digital controls set as high as you can. The post values.
IN to gnd is 4.8vdc
@bbowley2 just checking to be sure… when “IN” is 4.8V did you try to fire the laser with the test button?
If I recall not that long ago you popped a supply and sent me your old one, right.
Symptoms
…Your green led is on so you are getting power to the supply and low voltage is being output.
…The “IN” is 4.8VDC and when you push the red “test” button on the LPS the laser does not fire…
…You have checked all wiring to the tube especially the cathode wire?
Other checks
Do you have a current meter installed? If not I think the cathode should be tied to the -L of the LPS and ground. You can check.
…
It sounds like a dead HVT or it could still be your tube. To do final check we would have to do an arc test on the LPS.
Once you have tried and checked everything else I can walk you through this test but its a last resort test because its dangerous …
…
Have you been running the machine a lot, the supply looks pretty clean inside? How many hours of use?
Seems like an excessive failure rate.
What kind of coolant are you using in your system?
I haven’t run the machine very much. I mostly use the K40 to cut 1/8" acrylic for engraving on my Piranha FX rotary.
I’m using distilled water running through an aquarium chiller with a 1 gallon tank that houses the water pump. I use a small amount of aquarium anti algae power.
@bbowley2 have you checked the cathode wiring as suggested above?
All wiring checks out. Absolutely no discharge using a chicken stick. It can only be the HV fly back. This seems to be a field repairable problem. There is a 3 pin plug on the back of the HVT. I will look for the part online. Thanks again.
Same problem. Wold this be the red machine? Still trying to get something worked out with the seller. They insist it is the water protection circuit.
same problem with a brand new blue box machine. pot checked out on a meter, psu comes on, same diagram as above but i have a red led instead of green. tube is wired correctly, will not fire in test.
Video I sent the seller this morning. Now they are saying once I return this one they will send another one…
@Gary_Balu @waco_kid Let us know how it goes with the seller.
Does the laser light up at all when you pressed the test switch on the LPS?
In the mean time if you can use a DVM do the same measurements as @bbowley2 above on IN with the digital power controls or the pot at its highest setting. Should be close to 5V when measured to gnd.
@Gary_Balu you can verify the WP sensor is working just by shorting it out and trying the test button, but the test button overrides that circuit.
my unit was bought back in april and has been in storage since so kinda screwed with contacting the seller at this point. my own fault, should have known better and tested it when i got it. i have another blue box k40 that i’ve had no problems with so testing wasn’t a high priority. zero power to the tube, does not light up at all. red light on the psu shows power going in, nothing coming out. most likely going to buy a new psu and trouble shoot this one in the background and if i can bring it back, then i’ll just have a spare on hand