Power load loss using PPI ???

[bluewave65]

Hello to everyone,

i got a problem with PPI setting.
My co2 powersupply simply dryout during cutting.
If i cut a square every line from start is thinner and thinner. ( Power reduction )
Got anybody same problems ?

Maybe quick capacitor discharge ?
I don`t understant it ...

Thanks for help

[Tech_Marco]

What kind of Laser Power supply you have?
Send me a picture. I'm assuming it works ok without PPI, correct?

It seems that your PS can't handle high frequency for the TTL input

Do some test like setup PPI to 50Hz, 500Hz, 2000Hz... see which one it works out and which one it doesn't

If your're using "TH", then try "TL" or vice vesa.


Marco

[bluewave65]

Combination tube + ps from coletech :
http://www.ebay.com/itm/40W-CO2-Laser-t ... 255c0acc98

But it looks different ......
PS inside :

Looks exactly like ps from :
http://www.ebay.com/itm/40-WATT-HIGH-EF ... 3cc01c0eb0


It works correct without ppi or with low ppi values like 50
There is a problem with 500 and higher ....
I`m using TL i will try TH

What do you mean : vice vesa ?

[Tech_Marco]

I think the TTL circuit can't response to the high frequency in this case.
Could be the tube but I'll consider as the 2nd suspect.

When you paid unreasonable low price for laser tube and power supply, you're expecting issue.
Someone on eBay selling a 700nm Co2 tube for $175 with S/H. It's totally not making sense as it's under my cost.
Well, it's just my though may be I got ripped-off by my supplier

Anyway, "vice versa", I mean either TH or TL for firing control. Ignore it.



Marco

[bluewave65]

Do you think pwm setting can be involved ?
I think it is a supply problem not a tube

After problematic ppi job supply is not able even a fire tube.
After some time supply regenerate and everything looks fine.
It doesn ´t look like a input circuit problem more like a part of circuit aroud a high voltage and transformer.

[Tech_Marco]

As I said, the laser power supply seems the main suspect.
Most laser power supply got two controls: PWM/Anlog input and TTL (eable the PS)
For a good PS, the TTL (TH or TL), it can support as high as 20KHz. That's why I asked to test it with low frequency like 50, 100 on PPI. Then set it to high 1000 or 2000. If it works OK with 50 or 100 but not 1000, chance is that your PS either not support high frequency TTL or the TTL circuitry is bad.

Marco

[bluewave65]

As manual says :

Response time <= 1ms
PWM Control : 20khz - 50khz

I will try change TTL-L to TTL-H driving + 50-100 ppi and report .....

[Tech_Marco]

That's for PWM input frequency but not the TTL input control (TH/TL)
If it's the TTL frequency issue, then either TH or TL won't be any difference.

Marco