Profile Panel RGB Power

Hi there,

Almost all LEDs in this industry use DC power. While AC LEDs exist, their use is still somewhat limited to my knowledge. When you think about the 'diode' part of LED, you can probably imagine why. You are also correct - the LEDs are dimmed using something called pulsed width modulation (PWM), the frequency and duty cycle of which will be dependent on the unit's hardware and software. You can probably answer both of these questions yourself if you have a little bit of technical inclination and a few basic tools. Of course I must point out that if you open a unit you run the risk of voiding the warranty at best...electrocuting yourself at worst. Anyways, just one look inside will confirm that the LEDs are DC, and a basic multimeter will tell you about how much voltage they're getting. Alternatively, you could look up the datasheets for the voltage regulators and transformers and find out that way too. I would take a guess that your LEDs are running at 5VCD, but that's just a guess. The frequency and duty cycle will be a little trickier to figure out. Inside the unit you'll see the two main microcontrollers and associated frequency crystals. Using that information it's possible to determine at least a ballpark estimate of what the PWM frequency might be. The easier way is to measure this using an oscilloscope. Why do you want to know this information?

prolightdesigner, thank you for taking the time to respond. That confirms what I suspected about the use of DC in the LED fixtures, but I like to avoid making assumptions. I have enough technical inclination to not worry about electrocution, but I am averse to voiding warranties. I have 16 Profile Panel RGBs that are currently just paperweights due to two issues.

1. They flash once every 8 minutes or so when connected to DMX, even when they are not part of the current scene.

2. They flicker terribly when recording video.

The DMX flash is a monster of a problem all its own. By identifying of the pulse frequency of the dimmer, I am hoping to address the latter issue. I've come across a handy page from David Satz discussing LED flicker, and I am hoping to employ his methods of adjusting shutter angle and frame rate to reduce LED flicker in video recording. Since I do not own a flicker meter, I thought I would check with the experts in here to see if anyone knows the frequency for the internal dimmer in this fixture. I'll have to read up on pulsed width modulation, but it sounds like it is probably not sinusoidal and more likely square. As long as the waveform is consistent, I should have a chance to synchronize the frequency. If it is variable, then I will probably have to abandon the idea of using the Profile Panel RGBs in scenes that are video recorded altogether.

Yeah, I can see why this would be a problem... The flash every 8 minutes will either be an issue with your controller or with the units themselves. Which controller or light console are you using? If you're certain it's not the controller, it would be a problem with the unit's microcontroller. Looking down the parts list for your unit, ADJ sells an "Upgrade Master IC Chip". I have no idea what the upgrade is... Maybe it's worth your time to call ADJ Service and inquire. It's possible that you got chips with a firmware bug. If that's the case, I would hope ADJ sends you replacements free of charge, but one can only hope. It's always worth a try because that definitely shouldn't be happening.

The flickering is another issue all together. The waveform is definitely square - on or off. LEDs can't actually dim (at least not very well), so PWM really helps us out here. I certainly wouldn't call myself an expert nor do I know much about film, but I can see what you're trying to accomplish. To my understanding, the frequency of the PWM should stay consistent whereas the duty cycle will vary in accordance to the desired brightness of the LED. The trick is, don't confuse frequency with duty cycle - a quick Google search should help you visualize this if you're a little unclear on it. I suppose what you're trying to do can be done, but I imagine it will take a lot of trial and error. What will only make things harder though is that when you have, say, Red at 75% and Blue at 60%, you'll have two different duty cycles to contend with at the same time. Unfortunately, units like the Profile Panels have no place in a video studio - they're not designed for that and as such use lower cost electronics to help keep the price down. If these are absolutely unusable, you could always consider selling them and buying fewer but higher quality units as a suitable replacement. I know that's not what you want to hear, but best of luck making these fit your needs!

Jeff,

Thanks again. I also noticed the "Upgrade Master IC Chip", but I could not find any kind of data sheet about it. I actually came across it while looking for a replacement power supply and hoping to find the frequency from its spec sheet. The replacement power supply is there, but no additional info is included in the description.

The use of these units for video recording is secondary. Their primary function is live presentation. If I can fix the unwanted flashing, I can bring these back online for shows. I'll probably be acquiring conventional lighting for the video work. I'm just lamenting the fact that I won't be able to play with the color from the DMX controller.

My controller is a Jands Vista S3, by the way. I've run it with Byron Vista 2.2 and 2.3 beta through both Mac and PC systems. The flashing has been a problem with all configurations.

Christian

I would definitely call ADJ Service if you haven't done so already. Your console is a solid piece of equipment, so I highly doubt that's the source of the flashing problem. Just to be sure, do you have a cheap light board to plug the lights into and see if the same thing happens? I'd still call service - for all we know the 'upgrade' chip fixes this problem!

The flickering is a different story - I don't think you'll be able to do much about that. I hear you about wanting to use these as much as possible though. On the bright side, LED technology is only getting better so maybe when it comes times to rotate what you have out of your inventory there will be something on the market that's a more suitable replacement. Hope this helps!