Scanner Problems

[Jenus]

I've also had this problem with my DT40W, but only with one test pattern so far: The grayscale gradient rings in QS and Beyond that are good to see how the whitebalance is.
It has never happend during shows.
Would be nice to know what causes it.

[mccarrot]

We had the same issue on one of our projectors last week during a show.


I put i wide pencil beam frame on for a few minutes to take a picture, after a minute a saw it go slowly start distorting.
After a power down of the projector it was fixed again.


We had 2 similar projectors with dt40w, but one with the cheap dt40 psu, and one with a more higer current psu.
Guess which one went bad. The one with th underpowered dt40 psu.


During live shows i turn the scranrate down to a avarage scanrate of 20k, beams are brighter and sharper at this scanrate.

[LEDpaint]

I had the same problem with my DT's and I also unplugged my projector to reset them. Tried lowering the number of points, set the scan rate to 24k, lowered the scan angle, nothing worked. I put a huge fan pointed directly on the amps and heat syncs, problem solved. They simply weren't getting proper cooling.

[KGB]

I would hope that isn't my problem... I have way too many fans already pointing directly at the scanner amps...(but ill try that at my next show)




its worth it to note that on my scanners I never have to worry about beams going crazy in ppls faces when it messes up.....The beams always stay in the correct zone..its just the animation that turns to mush.....is this the same thing that is happening to everyone else?

[mixedgas]

External Lytic caps folks, add them, as the Chinese put very tiny ones in the PSUs. This stiffens the psu rails. It helped me a lot, but I went back to big linear PSUs when this happened with my Chinese pair. Watch your grounding. Steve

[LEDpaint]

I should also note my amps are mounted on fairly thick aluminum plate. I was able to touch the back of the plate with no discomfort, but apparently they were still getting too hot. Try putting them on a nice extra-thick slice of plate in addition to the extra fan. I'm not super-technical but perhaps a TEC could be mounted on the underside of the plate?

[KGB]

So here is where it gets weird..... Its been 2 months since I posted about this problem and since i posted this thread my lasers have been acting fine.... what would have used to mess them up now works fine.... anyone have any ideas why they just started working.... I didnt do anything to fix them???

[mixedgas]

Damaged Polyswitches and Lytic caps often "reform" or "heal" over time. Has to do with electro-chemistry in the devices. Certain older types of Electrolytics are made more like a poor quality battery then a capacitor. Lytics are "formed" at the factory to create oxide films in the caps. Puncture the oxide, and you can have all sorts of problems. Things like dendrites do form in parts, then get blown away later. Early lead free solders were notorious for tin dendrites.. Also films form on connectors, even gold plated ones..

I dont know what happened in your case, but its not the first time I've heard or seen boards come to life. Not just laser stuff, computers, two way radios, lab gear...

Check the lube on the scanner bearings too. I have a pair of Asian scanners that freeze up over time, when unused. I loosen them with pliars, scan a bit, and the lubricant re-distributes, and they work just fine.

Steve

[LEDpaint]

Funny, I was thinking about this thread the other day...Check those little daughter boards on the amps, maybe one is loose. That happened to me on my first set of DTs.

[mccarrot]

Or you are not scanning wide enough, or using different frames.
try a pencil beam fan (allot of accelaration and braking) on the widest scan angle

this will help in my case to get the DT40W with original amp to go "strange"