Behringer LC24/12 - LED lights 'freezing'

[boardingbob]

Hi all

My other half bought this desk, knowing its limitations, for a small schools tour where he just needs to do some very simple lighting cues with LED pars. I programmed it up for him and it has been working well - until yesterday.

During the show (run via pre-programmed cues on the faders) some of the lights 'froze' and refused to change colour/intensity. The colour LED backlights were the ones that froze whereas the warm/cool white ones doing the front light did not. All are directly wired to the desk. He rebooted the desk to no effect.

I suspect that there is a dodgy cable (or possibly lighting unit) somewhere in the run, but just wanted to check if anyone else has come across this as a desk issue. 

Cheers

[bruce]

Guess: maybe the backlights" which failed are set to maintain current state on loss of DMX, and there's a cable fault between "front" and "bacK' - so back has lost signal. But could be all sorts of other things - that's just a guess.

Make sure there's a terminator on it - while the system may work fine without, a terminator will highlight faults and make fault-finding clearer.

Then it's a case of "disconnect and terminate" until you find the fault. Disconnect in the middle, check all works, if it does, add a bit more and test again.

Not sure what you mean by "all are directly wired to the desk" - assuming you have a simple single DMX chain, with no branches. 

(Presume that since you said LED Par, you're not using the analog outputs!)

 

 

[Don Allen]

I set up a chase in a desk, cycling through the led's colours, to test cables. This shows up cable faults as you flex cables as the colours stop changing if the cable flexes open circuit.

[boardingbob]

Thanks Bruce

A DMX terminator is a very sensible suggestion - will get one ordered asap. And yes, all configured as a single chain. Will interrogate the operator further to see if the 'faulty' units were the ones at the end of the chain or not. 

🙂

[boardingbob]

Thanks Don - I'll have a go at that too if the terminator doesn't smoke out the problem by itself. 

As all the kit is less than 3 months old I'm more than a little pxxxxed off that ANY of it is showing a fault so soon...

[Brian]

Does the desk have a switch on the back to swap pins 2 & 3? Maybe it got knocked? 

[dmxlights]

On 7/14/2022 at 6:31 PM, Brian said:

Does the desk have a switch on the back to swap pins 2 & 3? Maybe it got knocked? 

I have one of these desk and no it does not have the switch to swap pins 2&3 around.

 

As others said it looks like a faulty cable or the cable got pinched on something that moves and broke it. It also could be a faulty socket but less lightly to be that

[Hilary Watts]

I've had one of these desks for over 10 years and have never come across this particular issue so I too would think it's a faulty lighting unit or faulty cable.   The only (minor) problem I have had is that when using the submaster/memory faders the output stays at about 3- 5% even when the channel fader is at zero.  This is hardly noticeable with tungsten lamps but the LEDs to which I have access still produce some light output.  It doesn't cause a problem (the master fader can be used for full blackouts) so I've learned to live with it.