White block on red wire next to laser tube started to crackle and catch alight

hi everyone ive been using my k40 for just over a month with great results then i heard crackling coming from where the laser tube is situated powered down took a look inside and noticed the wire was starting to catch fire near the white ceramic block can i change this block and rewire the wires to a new one and if so what type of block am i after thx

That’s scary!

Can you post pictures please? Different K40s look different, and pictures help avoid misinterpretation.

this is the wire thx

Yikes! Is that a spliced wire? I’ve never seen something like that in a K40 before.

dunno if its spliced as its going into some kind of ceramic block

So does one wire go to the power supply and the other wire go to the tube?

yh as far as i can see but the wire right next to the block was trying to catch alight so i switched off straight away

My guess is that you had a crack in the insulation on that HV wire and it was arching to ground on the case probably. @donkjr is the HV guru here and we can see what he says. If that’s the case you will probably have to cut the ceramic block off and cut and strip back to good insulation. You can then resplice the wires.

See this link for information on splicing HV wires (please read this link as HV is VERY dangerous)

You could also use connectors like these:


cheers sounds like this is happening

Please read Don’s blog post before doing any splicing as HV is very dangerous.


surely if im using the connecters you said to get there would be no need to wind the two wires together or am i missing something just want to make sure ive got evertying in my head before i start the job

Are there any markings on that white block?

Please post a picture of the LPS showing the connections.

Is that white block in series with the laser tube’s anode?

What do you mean the “wire right next to the block” is there another wire involved other than the two red wires.

no the white block is attached to the red wire one end goes to laser tube other end goes to power supply

Just want to know what type of supply it is…


there one red wire in the casing where the laser tube is its a red wire as shown in the picture with a white ceramic block on it

sorry if I made the request confusing. I would like to see a picture of the actual LPS showing it input wiring.

thank you donk i just saw about the connecters bit thats all i wanted to know cheers

i just opened the power supply and the red wire goes straight into thepower supply bourd at the back

I am referring to a picture of the front side of that supply.
By seeing those connectors I can tell what vintage supply it is.