Automated Fixtures Troubleshooting Flickering MAC2000 Performance


I have recently gotten my hands on several Martin MAC2000 Performance fixtures that have been heavily used but still seemed to be working fine. I did a very quick test of all the functions with them sitting on my stage and everything looked fine. I have now hung them (so they are upside down from before...which may not be relevant info). Each is plugged into a dedicated 20A 120V circuit from my Unison rack (using the CC20 module for constant non-dim power). As far as I can tell my power is stable. Shortly after striking the lamp on two of the units they start flickering (but a slow flicker, more like a "mode change"). I have everything open (no color, shutters, iris, etc) and just point them at a wall for initial tests and they flicker. They do not flicker at the same moments as each other and the flickering pattern appears to be random. They seem almost to be jumping to a 80% mode and then jumping back up to 100%...almost as if there is some sort of "power saving" mode that it is jumping back and forth between. Does anyone know what might be going on? Thanks!
Well... there's a lot of could be's. It could be the power, does it still happen if you switch dimmers/modules or put straight into the wall not through a module? Is there anything else in line with those units? How is the DMX to and from those units terminated? There is a possibility that the lamp is not seated correctly, you'll find that out fairly quickly however because it will die. There is a very slim to nearly no chance that you happen to have two units with bad capacitors in the PSU... if that is the case go buy a lottery ticket and prepare to retire because you should almost certainly win.

my initial guess with it not being seen in other units is that you're experience a power fluctation, or dmx gremlins. I would separate them and then add pieces back into the puzzle until the picture becomes clear.
They were fine right-side-up, but now that they are flipped, you get a random fluctuation/flicker?
If the power checks out, you might want to try rotating the lamps 180. Sometimes, HMI lamps can develop issues that are position dependent. An "Arc" light is called that because the plasma flow is shaped like an arc between the two electrodes. Because of this, the tips of the electrodes can develop pits. Rotating the lamps may move the arc to a better area of the electrodes. There are a lot of other things that could be wrong, but swapping or rotating the lamp can be the "no cost" answer.
Erratic flicker of this nature is most likely going to be power related. Have you metered the power to the units? Are the MAC 2000 Performances designed for 120V? The VL3000s are 208V, which is why I ask (the fixtures are somewhat similar in design/nature). Depending on the socket, you can't just turn the lamp. If they are newer fixtures, and have the improved SFc10-4 Socket from OSRAM (I hate to brag here, but this one is completely fair as the OSRAM socket for this fixture/lamp type is quite frankly AMAZING and was game-changing. ), then the slots where the lamp base snaps in are keyed, and the lamp will only go in one way- with the fill tip aiming down into the reflector. If they have the older socket version, and it contacts the lamp on the threads at the ends of the base, then you can turn the lamp in any orientation. I agree trying straight wall power (not going through the dimming rack) as a first check, to see if you can rule that out as a potential cause.
Yes, the units are designed to be able to run on 120V @ 20A and I have verified stable power. I have 4 other identical units in the identical setup and they are all running fine. I have confirmed that this is not a DMX issue, as it happens when isolated or inline with many other fixtures. The run is also properly terminated. I previously reported the issue in two units, but it seems to be only in one at this point, but still have not had time to stare at each one long enough to be 100% sure. In the one fixture which is really bad, I have replaced the lamp with a brand new one (and yes, my socket is keyed so the lamp is facing correctly). The issue seems to only happen when the shutters are open (if I look at the light the spills out of the cracks at the back of the unit, the light does not appear flicker when the shutters are shut). I am pretty sure I read somewhere that when the shutters have been closed for some amount of time, the fixture reduces power to the lamp to reduce heat buildup inside the fixture. Is there a shutter sensor that might be acting up, causing the fixture/lamp to drop in and out of that lower power mode? I really hope that the issue does not require replacement of the main circuit board or the electronic ballast...looking for cheap answers! There does still seem to (maybe) be a positional component to this as well. When it is pointed directly at the floor it does not seem to flicker (or I have not caught it doing it)...but when pointed sideways (at my stage) it is quite apparent. I will keep testing the directionality theory a bit more and report back.
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