Control/Dimming The joys of retrofitting (or a tale of Microplex conversion)

Krawford

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Joined
Mar 9, 2015
Location
Canada
I recently got a Leviton I/F 501 interface unit in order to upgrade the controller in a small theatre i work in. I'm having an issue with slight intermittent level flutters and the fellow on the leviton tech support line and I have exhausted his troubleshooting diagram. Anyone on here ever have an issue or some experience with these boxes?

I'm running dmx->protocol converter->3x NSI dimmers and have tried three different dmx controllers in the chain.
 

microstar

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Jan 19, 2014
Location
Lawton, OK
What DMX controllers have you tried? If you have one that lets you select the DMX speed set it for the lowest and see what happens.
You might also double-check that all of the IF501 internal jumpers are set correctly per the instruction manual for the DMX to Microplex conversion.
 

Krawford

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Joined
Mar 9, 2015
Location
Canada
What DMX controllers have you tried? If you have one that lets you select the DMX speed set it for the lowest and see what happens.
You might also double-check that all of the IF501 internal jumpers are set correctly per the instruction manual for the DMX to Microplex conversion.

Tried ramped down speeds and I set the jumpers to spec, but I think I'll open it up and recheck them when I go in in the morning. thanks!
 

Krawford

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Mar 9, 2015
Location
Canada
and the controllers I used were a smartfade a leprecon 524 and a enntec dongle

And all the jumpers are in the correct spots.... I'm all out of ideas at the moment....
 

microstar

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Jan 19, 2014
Location
Lawton, OK
Well here's another shot in the dark.... I ran across an existing permanent installation of NSI Microplex controller to NSI Microplex dimmers that started having flickering problems after a couple of years. Tried everything and then substituted a Lightronics controller and the flickering stopped.
So sent the NSI controller to NSI for repair. They asked how far was the controller from the dimmers and I said maybe 200' (although I can't remember the exact number). They attached that much control cable to the controller and were able to replicate the flickering. They said there was too much voltage drop since the power for the controller came from the dimmers, and that with a lot of channels changing levels, that caused the flickering. The Lightronics console must have worked with the lower voltage better. NSI said to use the wall wart power supply that is usually only used with the optional DMX output and that would solve the issue, and it did. Kudos to NSI tech support on that one and they ended up not charging anything!
On a long shot, if it isn't already there, move the IF501 to your dimmer location and connect with a short cable and see what happens.
 

Krawford

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Joined
Mar 9, 2015
Location
Canada
control is 5' away and I've tried with a couple different cables.

I've also plugged the converter into it's wall wart and I still get flutters.
 

microstar

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Jan 19, 2014
Location
Lawton, OK
The only other thing I can think of is a bad DMX cable from controller to IF501. Do a continuity check or take it apart and make sure that the shield is connected ONLY to pin 1 and not also to the metal shell of the connector (on both ends).
Other than that, I'm out of ideas!
 

Krawford

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Mar 9, 2015
Location
Canada
I'll probably have to do that tommorow I've got a list as long as my arm today and a show in the evening. I'll write with an update in the AM!
 

Mac Hosehead

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Sep 10, 2014
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Shark Tank
This is not a problem I have seen before using this interface. It seems you have checked most of the possible issues on the input side. I assume this problem is seen across all packs at the same time? Intermittent how often? It might be time to look at the output side. What model of NSI packs are these? Permanent or portable? Have you bypassed one or more packs? Just as in the 5-pin cable, there should be no connections to the case in the 3-pin cable.

While you might have an interface with a hardware problem, intermittent issues suggest noise or heat. Maybe it's just Canadian power, eh?
 

Krawford

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Mar 9, 2015
Location
Canada
Yep I've got it terminated internally via p6, I'm going to grab the bits to make a dmx terminator when I'm in the city tomorrow just in case that bit isn't working.

The flutters seem to hit one channel at a time with the interval between being anywhere between 30secs to 60mins. It seems to be only affecting my first dimmer right now (a nsi dds 8800) but that may be a fluke.

three dimmers 1 nsi dds 8800 and 2 nsi nd 4600

The power seems pretty good, the standard is between 110v and 120v and I'm reading 123v on a power conditioner so plenty of juice.

No flutters when using a Microplex board with the dimmers so I don't think it's on the dimmers side of things.
 

Mac Hosehead

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Sep 10, 2014
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Shark Tank
So you have only noticed this in one pack? As a test I would try running the interface from a short piece of xlr at the pack with no other control connections. The fact that you do not see this with your microplex board does not convince me the problem is in the interface.

Mostly kidding about the power. I do occasionally hear stories of elevators affecting lighting systems.
 

Krawford

Member
Joined
Mar 9, 2015
Location
Canada
I think I've got it fixed! I made a dmx terminator and stuck it on the dmx out of the converter. That seemed to work for a while but then i got one flicker an hour or so later. I then had a memory flash: when i took apart the dmx cable I remembered a little bit of tape on the body ground and wrapped around the unused pins (old dmx cable and the rest of the pins looked fine thought it was a fix for some old issue). i took off the tape and what do I find? A resistor on pin 4 and 5.

So what I think happened is this the internal termination on the converter isn't up to snuff and i had one weird frankencable. with the new terminator in it was a bit better but somehow the resistor on the weird cable was messing with something. with an new cable I was good.

When I first troubleshot the lack of improvement with swapping the dmx cables must have been because of the lack of sufficient termination.

Thanks for the help guys, and if what I'm saying don't ring true please offer some alternate explanations I'd love to know If my explanation makes any sense.
 

Dionysus

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Joined
Feb 9, 2009
Location
London, Ontario, Canada
I think I've got it fixed! I made a dmx terminator and stuck it on the dmx out of the converter. That seemed to work for a while but then i got one flicker an hour or so later. I then had a memory flash: when i took apart the dmx cable I remembered a little bit of tape on the body ground and wrapped around the unused pins (old dmx cable and the rest of the pins looked fine thought it was a fix for some old issue). i took off the tape and what do I find? A resistor on pin 4 and 5.

So what I think happened is this the internal termination on the converter isn't up to snuff and i had one weird frankencable. with the new terminator in it was a bit better but somehow the resistor on the weird cable was messing with something. with an new cable I was good.

When I first troubleshot the lack of improvement with swapping the dmx cables must have been because of the lack of sufficient termination.

Thanks for the help guys, and if what I'm saying don't ring true please offer some alternate explanations I'd love to know If my explanation makes any sense.
A resistor on one end of the cable? THAT IS INTERESTING. I am curious to the size of the resistor? 120-ohm? Still makes you wonder, who did that, why, and what they were thinking. Glad you found that, hopefully you can clean things up?

What part of Canada are you in anyways? (BIG country lol)
 

microstar

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Jan 19, 2014
Location
Lawton, OK
Just don't rest too easy.... pins 4 and 5 probably are not even hooked up inside the IF501 on the DMX input unless they are just passed thru to the DMX out. Plain DMX does not use pins 4 and 5. Can't check inside my IF501 right now to verify.
 

Krawford

Member
Joined
Mar 9, 2015
Location
Canada
It was a 120ohm .5w. One of the previous techs was notorious for interesting undocumented gadgets so what i think is that he was going from 5 to 3 pin DMX for the first time in our main space, read the original dmx spec and thought to terminate the redundant lines.

I'm all the way out in the boondocks of Newfoundland!

And to as Microstar's comment it looks like they are connected at least as far as the circuit board.