Mystery Lighting Issues

One of my student techs is doing some pro bono lighting work for a local community theatre and has run into an issue no one can seem to figure out.

He added an LED wash light to their grid and then everything stopped working. Even after removing the new LED fixture nothing is functioning. I'm troubleshooting this over the phone so information is somewhat limited.

Console is a Colortran Encore. Hang is 8 LED wash fixtures and a few traditional fixtures run off dimmer packs. Apparently their is some kind of loss of signal somewhere because the board is acting like everything is on but none of the fixtures (LED or traditional) respond. All cables have been checked/swapped and verified as plugged in.

Any Ideas?
 
Have him check the patch on the fixtures. With generic LED's if they lose signal or power they tend to go to a different mode, like master/slave, as opposed to dmx mode... or 3 ch vs 7 etc...

Although it wouldn't explain the dimmers, unless the LED he added had a short and sent power through dmx... I really hope thats not the case.

Maybe check the breakers, hopefully he just tripped one.

If breakers are good, than start bypassing fixtures (take a fixture out of the loop 1 by 1)... to see where your signal drop is.
 
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LED addresses are all still patched correctly. Breakers were all good as well. That's the first thing he checked. Bypassed fixtures down to the last one and still nothing.
 
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Then i would start bypassing fixtures. 1 by 1 to see where the signal drop is. Take 1 fixture off the loop than closing the loop to see if the lights come back on. This is a lot easier, and a whole lot faster if he has a cable tester...
 
I'll have him try that next. Thanks for your help guys. Didn't think about the board being damaged. Its pretty ancient from what I've heard.
 
ftp://ftp.leviton.com/LevitonFTP-Public/LES/Library/Manuals/Manual%20-%20Encore.pdf

Manual in case y'all didn't look at that yet.


Page 18, that would be awesome if that was it

Best test is to grab a 8ch board , best thing to have for troubleshooting anything or quick focus.

I would swing over UNI1 to 2 and see if you have the same issue as it looks like all versions of the board have 2 outs.
 
If the transceiver chip is blown, it is an easy fix and only cost a buck or two. It would be ashamed to throw away a board if it is such an easy fix. The first thing to do is to build or get a DMX tester that is just some LEDs and resistors. You can find them on the net for a few bucks, or there are several sites that tell how to build one. Just Google DMX tester and go from there.
 
Just for clarification's sake, the mythical transceiver chip I keep hearing of is just an RS-232 to RS-485 converter, right?
 
Just for clarification's sake, the mythical transceiver chip I keep hearing of is just an RS-232 to RS-485 converter, right?

It's actually a TTL or CMOS to RS485/RS422 converter. The SN75176A is sort of the default/original choice, but there are lots of other pin-compatible chips that have slightly different characteristics and advantages. For example, the SN75LBC182 has better ESD protection and is slew-rate limited (which tends to make it a little more tolerant of poor wiring practices).
 

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