Hi guys I have a problem with my k40 I’m hoping someone can help me with this problem, I was cutting some 2mm ply when my laser had a sudden drop in power down to 10mah so obvious thought was tube has gone so ordered a new tube installed it and still the same , then I noticed what looked like a small crack with a D at the side of it which I presumed meant damaged so got onto seller and they sent another tube installed that tube and still the same now I’m thinking psu, any advice would be helpful thanks
That sounds like the high voltage fly back problem. You can replace these quite cheap but you have to bare in mind they do carry “HIGH VOLTAGE”
If you open up the psu you will see it at the back with the red HV lead coming out of it, check the numbers and style of it and order a new one and I’m sure you’ll be good to go.
@Andy_Shilling nice one mate I will have a look at that is there anyway of testing it? Or is it just simply just buy and try
@Craig_Goddard1 no your can’t test it, when mine gave up the ghost the laser would fire at around 5amp down to 1 Amp-ish but after another half hour of trying to work out what was wrong the laser then wouldn’t fire at all.
I ended up buying a better psu for an eventual upgrade but also got the flyback as it was only £16 and I now have a spare PSU.
@Craig_Goddard1 what @Andy_Shilling said.
Do you hear an kind of hissing or arching from the HVPS?
Does the current meter jump occasionally?
@donkjr yes can here bit off a hiss when firing but can’t see any arching but not taken the cover off the psu yet to have a look, currently in the hospital waiting an X-ray as I dropped a steel plate on my hand, I shall have a look as soon as I’m out thanks for ur help I’ll keep you posted, I’ve not yet come across this problem and the only hpvs I have come across are in China or Japan so will be a couple of weeks when I order one
Oh and no doesn’t jump occasionally really miffed me this fault, thought couldn’t be 2 faulty tubes
@Craig_Goddard1 the hissing is usually the HVT breaking down. Coincidentally mine just started doing the same thing …uggh!
As @Andy_Shilling said you can replace the supply or the HVT.
Post a picture of your supply showing the green connectors when you can.
I hope your hand turns out to just be a bruise ok …
We do not know of any way to isolate the LPS from the tube in terms of which is bad. Since the tube is new, its likely the LPS that is bad.
You can buy a new LPS or replace the HVT. Replacing the HVT is not guaranteed to fix the problem but it does most of the time.
So you have to decide do you want to change the HVT for $32:
Or
The entire supply for approx $100:
…
WARNING: the LPS outputs LETHAL voltages and can kill you. You use this posts advice at your own risk. Follow HV safety and troubleshooting procedures. If you are not qualified working with High Voltages DON’T REPAIR THE LPS.
…
The above part links are for reference and may or may not fit your machine. Check your HVT carefully before buying a replacement.
If you buy a direct replacement for the LPS you will not have to rewire. Make sure the connectors are the same style and configuration.
Repair and other information is here:
Ok mate I’ve ordered a hvt, go cheapest first 
@Craig_Goddard1 OK keep us in the loop.
@Don_Kleinschnitz_Jr
Hey guys update on this fly back, it’s finally arrived but appears to be the wrong one but the seller says it will fit and sent me wiring instructions which I’m trying to get my head round or you guys may have experience with this and may say yay or na don’t do it? Not sure anyway pics to follow
The top picture is new and old fly back as you can see mine has 3 wires with a plug which I ordered and they sent me the new one which has one wire and no plug