Laser not firing

My laser does not fire.
I was removing the connections from the tube. Puthem 1cm apart. To see the arc.
The power supply arcs (1cm) only for a moment when I press the button on the front panel. When I keep it pressed it nothing happen. Only If i morse the button.
When I press the test button on the power supply nothing happen. I do not see any cracs on the tube. But might something small. The power supply gives 24v and 5v.
What do you think?

If the supply does not fire the laser with the test button down on the supply it is likely a bad LPS.
Do you have an analog meter on the machine?
If so what does it read when the LPS test button is pushed

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@funinthefalls is correct and I should have mentioned that your LPS is capable of a lethal electric shock even when the machine has no power.

How are you monitoring the spark (post picture).

Also, continually allowing the LPS to arc can damage the supply.

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The negative lead and a positive 1cm apart. On a wood tooth pick.

I know if the voltage builds up the flyback transformers isolation can brake down permanently.

Nothing on the meter when I press the button. I guess the voltage is not high enough because the flyback transformer. But I do not have high voltage probe for my multimeter. I saw on youtube someone was using a large resistor. But for proper testing. 20000v/20mA=1MegaOhm also higvoltage and 20w.

And also I was opening the power supply. Fuse was OK. I did not see any burns.
And I saw one of the week point of it. The bridge rectifier is surprisingly small. Compare to the 15A FET-s.
But still the flyback can be faulty. But no spark if I press the test button on the powersupply.

It sounds like your supply is bad.
I say this because when you push the test button on the LPS you are not seeing any current, no spark, yet the 5v and 24V is good.

How old and how much usage has it seen?

Typical failure is the High Voltage Transformer (it’s not a flyback).

Although there are procedures for doing so on my blog I do not recommend repair. The most common failure is the HVT but there may also be other component failures that have occurred at the same time. Replacing individual parts you can quickly exceed the cost of a new supply and still not get it operational.

Also the internals of the supply expose you to high voltages that are lethal to you and most equipment that you may employ for measurements.

This troubleshooting guide can help you eliminate any problems that may exist outside of the supply but the symptoms from above match my experience with bad supplies.

I have received my new power supply and it works.
Just to learning for others.
My tube did not fire. I was testing my HV by keep the + and - electrodes 2-1cm apart. By put them on a tooth pick. (Carefull this voltage kills you!!!) Before you doing that discharge the tube and the HighVoltage transformer with a MOhm resistor and wait util it happens. 20.000V is about 1cm spark gap in air. Carefull if you get the wires too far the spark will happen inside the transformer and damage the insulation permanently. If you are not sure do not do it…
The power supply did not give any spark with the test button on the power supply. But it was giving just one short spark when I pressed the front face firing button. Supposedly the HighVoltage transformer was faulty. The replacement of the powersupply solved the issue.

A post was split to a new topic: Help debugging upgraded power supply

Glad the new LPS fixed the issue.

For the benefit and safety of all:
From my experience arching the supply to find if it is bad is very risky:

  • Working anywhere around a live and disconnected LPS is very dangerous
  • Arching the supply can actually damage it if it is good.
  • You need to be experienced with HV troubleshooting techniques including using a chicken stick to discharge the supply
  • In fact unless the supply is dead, a partially working supply will still arc. How big an arc is needed to prove the supply is bad? The only real way to measure the LPS is with a high voltage probe which is to expensive for most.

The best way to troubleshoot this supply is “diagnosis by exclusion”, determine what is working until the only thing left is the LPS.
There is plenty of information here:

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I was checking the power supply.
The test button on the board of the power supply was not connected. There was no trace on the board.
That is why was arking only from the front panel.

I was checking the quality factor on the high voltage transformers HV side.
On the faulty one was 30 on 10KHz
And 130 on the good one. Might this test can be used to test the transformers. Without leathal voltage.

I need to know how the test was setup and run.
The problem is that its hard to tell if the HV diodes break down at high voltage unless you run them at that voltage.