I've got a rack of 6 Leprecon LD-2400 dimmers hooked up to an ancient LSC LinkLight Multiplexer (blue chassis, 3 pin DMX connectors) that is currently having issues with the fixtures glowing when the board is calling for 0. With the D/A disconnected from the pack, we are measuring 90V hot to neutral. The dimmers are showing the drive LED faintly lit, along with the output LED at the same level. Besides recalibrating the trims, any thoughts on what could possibly be the problem?
Control/Dimming LD-2400 ghosting issues
- Thread starterBobHealey
- Start date
http://www.controlbooth.com/forums/lighting-electrics/27595-nsi-dds9800s.html This may help! It's not quite the same issue, yet it still may help you as my dimmers are doing some of the same things.
FatherMurphy
Active Member
If I'm reading you right, you are seeing the ghosting even with the decoder disconnected from the dimmers. The most likely thing to try is to adjust the low trim setting on the two ramp cards to the left side of the front panel. Get a straight-blade jeweler's screwdriver about 1/16" wide, and gently find the slot on the rotary potentiometer just inside the hole (it's easy to miss, plus you have to guess a bit about what angle the slot in the pot is already positioned in). Tweak it slightly clockwise (iirc) until the ghosting stops, then do the other of the two ramp cards. The left card controls 1-3, the right one controls 4-6. After that, I suggest getting two matching fixtures and plugging one each into channels run by each of the two cards, and using the console to see if they still start glowing at the same point on the crossfader. If not, keep tweaking until they match, yet don't ghost.
While you're there, you may as well touch up high trim as well, I usually compare it to the test button level, tweaking down until I see a difference between test on and test off, then give it one slight tweak back up to match. Older packs had separate pots for each channel, later ones had a single high trim for the three channel ramp card.
If the dimmers stop ghosting as soon as the decoder is disconnected, then you have a problem with the decoder.
While you're there, you may as well touch up high trim as well, I usually compare it to the test button level, tweaking down until I see a difference between test on and test off, then give it one slight tweak back up to match. Older packs had separate pots for each channel, later ones had a single high trim for the three channel ramp card.
If the dimmers stop ghosting as soon as the decoder is disconnected, then you have a problem with the decoder.
We verified the DMX->10V decoder with a meter, its giving the expected voltages. As soon as we track down someone with an oscope and probe that doesn't mind 120V, we're going to be following the procedure outlined in the manual to retrim the things. Going to be using an ancient 0-10V LP-500 console as a control source (after calibrating it) for the retrim. Hoping we don't need to replace 36 channels of dimmer, since that wasn't in the cards for another 4-5 years.
FatherMurphy
Active Member
I installed a number of LD-2400's back when they were still in production, and the factory trims (set by oscilloscope) often ghosted a bit fresh out of the box, so I don't place a large amount of faith in that method of trimming, although it will certainly get you to a good starting point.
I guess I misread your original post as being six channels of dim, rather than six packs of six. The methods are the same, it will just take longer to get through the rack. Getting everything trimmed so that it all fades evenly can take some time, but that's part of the fun of dealing with older equipment.
I guess I misread your original post as being six channels of dim, rather than six packs of six. The methods are the same, it will just take longer to get through the rack. Getting everything trimmed so that it all fades evenly can take some time, but that's part of the fun of dealing with older equipment.
