My 1,2W in action on a LanParty (Warning: lots of pictures!)

[Francesco]

Nothing to worry about, version 6.57 is the newest official release...
The newer 7.00 firmware is for a beta release of QuickShow...

[Doc]

Possibly the truss was at some potential?

[hobbybob]

Hello Doc and others,

I have been thinking about this all night long last night too.
After having received another email message from Bill i have 2 possibilities.

Either the metal h-beam in the ceiling where i attached the projector using to 20mm steelcables to truss and then g-hooks to the projector was on some sort of potential. Because THAT is the only thing that IS different at home.

Or:
I have 2 FB3's. I use them alternatively, sometimes one, sometimes the other.
I have noticed when switching that it doesn't always work right as i expect.
This is due to the fact that sometimes i run my Green 1W off it, then my RGB and switch between them. As i wrote before in a message it looked like what happened last week when i hooked up RGB projector and it displayed in some sort of white only. It was on single color.
Bill wrote me that Quickshow remembers those settings, so it might have been that was on the single color. Still doesn't explain why the white beam came out. Here at home everything works fine.

So it might be the first, the potential on the truss coming from the H-Beam.
When i thought of this i am mad at myself i didn't bring a multimeter up, when i unhooked the projector, that way i could have measured between the projectorhousing and for instance the groundpin in the power cable... next time i will do that.
Since there are some heavy generators running outside that have an earthpin pushed deep in to the ground it might have been something like that. But on the other hand then, why is the Easylase not bothered by this ?

I will be in negotiation with the owner of the hall to come over there to play when he has not rented out the facility to try out some shows, effects and adjust !
It's a nice 90m long hall , 55meters wide. So i wanted to project a white beam, bounce it of a mirror and then adjust the beam over a 180m distance ! How cool and precise is that. And indoors ;-)
At that time i can measure if there is a potential on the truss even when there are no generators on.
I mean the roof can leak on some places so why can't there be anything wrong with the wiring ?

[Doc]

Ahaa! Generator using it's own ground, projector bolted to a truss connected to the building's ac ground........

Also, I believe that the FB3's colour channels are single ended?

[Francesco]

It's hard to say afterwards. In the past I had some problems with potential differences. This was solved by using isolated clamps, I now use 2x Manfrotto Super Clamp.
035..jpg
The power connections are not always great at some places..... I have got quite some times a shock from a truss at a show location. If you can feel it imagine what it can do to your sensitive projector...

Ahaa! Generator using it's own ground, projector bolted to a truss connected to the building's ac ground........

Also, I believe that the FB3's colour channels are single ended?

Correct, the color signals are single ended, the X,Y outputs are differential.


Hobbobob, didn't you told me that you had the same problems before you had the projector mounted up high in the truss?

[Doc]

It's hard to tell afterwards. In the past I had some problems with potential differences. This was solved by using isolated clamps, I now use 2x Manfrotto Super Clamp.
035..jpg
The power connections are not always great at some places..... I have got quite some times a shock from a truss at a show location. If you can feel it imagine what it can do to your sensitive projector...

I once blew the crap out of an audio crossover at a gig that had cross phases on the ac outlets.

[hobbybob]

I think this is the case, but have to check with the dude who does the power and electricity on our event. But i think it's highly likely that i am on the power of the hall (to have a steady no break current, or at least our servers run even in case of a failure of a generator. So could be i was on generator.
Since the hall also has a 125A, 400V 3 phase connection we ALSO use.

I mean powering 728 PC's (participants), around 40 game pc's (host for Dutch National championships videogaming) and around 80 visitor servers (fileservers/gameservers) and our own DHCP, DNS, Internet proxying takes up some serious juice !

We had a very clever 80Mbits up/down stream over 4KM from the roof of the hall (18m) to a nearby officeblock of a sponsor (100Mbit). We had 4 antenna's. 2 on our side and 2 on theirs to have a full duplex connection ! It worked like a charm.

So you might have been right about this all along.
Would it mean that if the colors are single ended and there was only as little as 5V DC offset this would turn on all the lasers to full ?
And since i used an old Easylase that still has differential color signals this would explain why it worked with the Easylase and didn't with the FB3 ?
The newer Easylases are faster, more colorsignals etc but also single ended as i understood from Laserwinkel.nl
So with a newer Easylase i would have experienced the same problems ?

[Francesco]

Hobbobob, didn't you told me that you had the same problems before you had the projector mounted up high in the truss?

[hobbybob]

Francesco that is true... You are right. With 15 minutes to go, i choose to hang it up since i was able to control it and with the Easylase it worked.
I burned 9 holes in a plastic garbage container i used as a "beam blocker" when i was trying to find the error, so on the ground before mounted to the truss there was also a white beam hitting the poor blue garbage bin. So francesco is right. Everytime the garbage bin started smoking one of my friends moved the container ;-) We ended up with nine shallow holes in the bin ;-)

So now i am back at square one, and even more puzzled.
PC and Projector where on same powerbar.
Placed on wooden table , there are rubber mounts underneath...

Damn, this laserstuff is hard to understand, well at least when it doesn't work ;-)

[ZwartLichtPro]

Hobbybob did the next things:

Day before the lan:
Everything checked out.. everything did worked..

Day of the lan:
..setting up the laser on his place.. (in the mean time the rigging was fixed for him)
..the FB3 (right?) was not working like he would
..checked out the other dongle, this one was doing what it should have to do.. (this was in case of safety)

If the problem was a ground problem.. than should the groundleak (power security) have been switched off..


Reggards,

Hobbybob's light and sound supplier

For the pictures we used a scissor lift (platform)

[White-Light]

I'm wondering if another possible problem could have been rf interference.

With all those pc's, and a high power wireless connection on the roof, maybe there was some stray signal that was interfering with the FB3's circuits. Only another possibility so don't jump on me too hard if some reason the FB3 is protected against this.

[hobbybob]

Just to make it clear:
ZwartLicht Pro is the guy arranging all the lights and sounds for our event.
I am sure he will properly introduce himself in the Lounge ;-)

And i don't agree that the groundleak (is that a proper word) would have jumped out.
If there is a potential difference strange things can happen and not always the breaker would have tripped (like we all experienced some time in our careers) so that i do not agree.

And where peter mentions Dongle he means the Easylase DAC (there might have been a mixup in words, as i showed him my Mamba Dongle and told him that QS was using the FB3 as a dongle device (next to being a DAC in the first place).

I still think it's very plausable that there was a ground potential difference of me running of the generator (with it's own earthing pin rammed into the ground) and the laser hanging of the ceiling beams (being on the buildings earthpoint, which is probably 50 to 100m away from the generators earthing pin.

A few volts would already be enough to introduce strange things like this.
Will ask Peter (zwartlicht pro) to supply isolated clamps next time to rule this out.
Or i will isolate my own G-hooks/ clamps.

[ZwartLichtPro]

@Hobbybob:

it's done in the Introduction topic.

[hobbybob]

Well Done peter, and welcome on PL forum.

I have received some more photos from Peter which i will place in this post.
What was really incredible to see during the LAN is that, since i used the Easylase DAC, i was able to use the LASERCAM software. I connected a Logitech webcam to an USB port, selected the live preview and pointed it towards the path between me and the large podium in the middle.
Then when people came walking up towards me i waved and ask them to do the same.
Some did, some asked why... i then pointed towards a large white camouflage screen we hanged in the back of the hall (75m away!) and said : LOOK YOUR PROJECTED REALTIME !!!!!

When they noticed it was true and not a prefabricated show, they did all kind of funny dances, waved, took stuff out of their pockets and held in in front of the webcam.
It looked nice and certainly had a lot of people interested in Lasertechnology all of a sudden.
The guys liked the software/hardware part and the ladies loved the nice red 640/642 from Kvant ;-)

I also converted some Clan logo's using TraceIT and projected that onto the wall.
Next time we will probably make a 3 by 10 meter white projection area in the back and then 2 greens flanking the RGB....

Here are some more cool pictures taken by Peter in the scissor lift at 75 meters distance and at a height of about 6meters high.

Take special note of picture 3 ;-)
The Dutch viewers will understand, but the beamer in the background says:
Lasers
Any laserpointer above 5mW will be confiscated without warning when you shine with it.

At last years event people people thought it was funny to damage our 2000+ euro controllable webcam (with very high quality zoom) a real security camera shining a high power pointer in it's CCD.
So in the rules they are told that bringing laserpointers is forbidden.

Although a very serious business, i could appreciate the humor in this picture, my 1,2Watt shining happily (ok above public and not into any expensive networked/controllable camera's).











http://www.photonlexicon.com/gallery...1/_MG_2482.jpg

[mccarrot]

Is your DC ground connected to the AC ground?

Never connect the DC ground to the AC ground, this can give you ground loops, causing the ground to be lifted with very strange behaviors.

(Especially with generators with a 3 phase generator in star, the star point of he generator is the Null, this is connectected to AC GND, unequal phase load will lift the Null and GND)

Keep in mind some lasermodules got there casing on DC GND, if this is the case you need to isolate the modules from your baseplate.