Lexel 95 Laser problem

[Thorsten Jungblut]

Hi!

i don't know if this is the right group to ask, perhaps someone can point
me to another group:

I got a Lexel 95 Laser (large frame water cooled laser >3 Watt).

I'm hoping my english is good enough to describe the problem:

I am switching on the power supply. The cathode is heated (voltage around
3.6 V A.C.). Now i am pushing the start button. The laser ignites but
shuts off immediatly after ignition. There is only a spot of
dark-blue/violett light (bright enough to be seen in daylight), no laser
beam.

The current meter jumps up to around 5 A immediatly returning to zero too.

D.C. voltage is 300 V before and after this "flash", A.C. voltage around
130 V. There is another value "reg. DC 50 V", i don`t know what this is
good for, but it is at zero, just flashing up like the current meter.

The procedure can be repeated without any changes. The PSU is in current
regulation mode, i tried out various current settings, no changes.

My first thought was that the tube is up to air, but i doubt it would
ignite at all, go up to 5 A (probably more because the current meter is to
slow to show it) and show a dark blue spot.

Any thoughts what could be wrong?

Viele Grüsse,
Thorsten

--
Thorsten Jungblut
Universität Koblenz, Fachbereich Informatik
http://www.netcorner.org/

 

[Sam Goldwasser]

Thorsten Jungblut <tjungblu@uni-koblenz.de> writes:

Hi!

i don't know if this is the right group to ask, perhaps someone can point
me to another group:

alt.lasers, will forward.

I got a Lexel 95 Laser (large frame water cooled laser >3 Watt).

I'm hoping my english is good enough to describe the problem:

I am switching on the power supply. The cathode is heated (voltage around
3.6 V A.C.). Now i am pushing the start button. The laser ignites but
shuts off immediatly after ignition. There is only a spot of
dark-blue/violett light (bright enough to be seen in daylight), no laser
beam.

The current meter jumps up to around 5 A immediatly returning to zero too.

D.C. voltage is 300 V before and after this "flash", A.C. voltage around
130 V. There is another value "reg. DC 50 V", i don`t know what this is
good for, but it is at zero, just flashing up like the current meter.

The procedure can be repeated without any changes. The PSU is in current
regulation mode, i tried out various current settings, no changes.

My first thought was that the tube is up to air, but i doubt it would
ignite at all, go up to 5 A (probably more because the current meter is to
slow to show it) and show a dark blue spot.

Any thoughts what could be wrong?

How long has it been unused? The tube may be high pressure. Not up to
air but too high to stay lit.

More info in the Laser FAQ, but probably best from the alt.lasers newsgroup.

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the feedback form on the S.E.R FAQ Web sites.

Viele Grüsse,
Thorsten

Thorsten Jungblut
Universität Koblenz, Fachbereich Informatik
http://www.netcorner.org/

 

[Steve Roberts]

1. using a ohm meter, check the passbank transistors for shorts
if they are not shorted, see that capacitor in power supply is charged
to 300V
make sure points on control card labled +30, +20 +15, -15 and 6.2V
have correct voltages, using a battery powered isolated volt meter as
most circuits are at +300V to ground.

tell us what you find and we will go to next step