Roboscan 918's

[ncprodmgr]

I have four 918's with the DMX jumping from fixture to fixture. Today during a performance the 4th fixture in the line lost it's DMX signal and stopped responding (of course the shutter was open). The DMX led went out on the fixture but the line continues on to control other items which continue work without any problems.

 

After 14 performances without any issues I am a little unsure on to proceed...

 

Any Ideas???

 

Thanks,

Jason

[jayselway]

As a first thought, if the DMX is going on to other units, through that 918, then it sounds like a dodgy DMX receiver chip.

 

Don't DMX problems always happen when the shutter is open!!!

[3guk]

A first thought would be, were you terminating the fixture ?? That sounds like a typical non termination problem !!

[Ynot]

A first thought would be, were you terminating the fixture ?? That sounds like a typical non termination problem !!

I'd doubt that - if the fixtures have gone through several shows already without incident, that tends to suggest something's changed. And lack of termination wouldn't cause such a terminal problem (pun intended! ) - thatusually manifests itself as noise on theline causing weird and sporadic movement etc.

 

I'd go with Jaselway's option - something LIKE a DMX receive chip failure or such like.

 

An afterthought - have you checked the cable/plugs on the last link to that fixture? If the cable was close to another unit and got hot enough to melt, that would almost certainly interrupt the DMX sig thus giving a total loss of control - or if the cable's gotten pulled and a disconnection caused inside the plug - worth a look....

[jayselway]

Of course, you don't have any Y-Spilts in your DMX line do you?

[ncprodmgr]

Of course, you don't have any Y-Spilts in your DMX line do you? :huh:

 

No such luck on the Y-Split... although I would gladly take that over the DMX chip... :blink:

[hippocrocaphant]

The XLR's on the back of the 918's are hard wired so that any DMX signal can be carried through the fixture even if the fixture is faulty or switched off. The DMX signal is taken to the main PCB down a wireset, which could be your problem... The DMX LED will come on when the DMX signal reaches the main PCB the fact that the LED has gone out but the rest of the chain is receiving data ok would suggest that there is a problem with the DMX wireset up to the main PCB

[Ynot]

The DMX LED will come on when the DMX signal reaches the main PCB the fact that the LED has gone out but the rest of the chain is receiving data ok would suggest that there is a problem with the DMX wireset up to the main PCB

I think you'll find that the OP said the faulty fixture was the fourth in a line of 4, so unfortunately that logic doesn't quite compute. I'd go with checking the cabling (by substitution perhaps) first, then taking a feed direct from the desk to the troublesome unit, then opening the cover to check for obvious causes inside, and if still no joy, then taking the fixture to a service rep, (though that may cost moe than the thing's worth....!)

 

TD

[hippocrocaphant]

[I think you'll find that the OP said the faulty fixture was the fourth in a line of 4, so unfortunately that logic doesn't quite compute.

 

Actually he also said the line continues on to control other items which continue work without any problems.

 

Which suggests that the data line is clean and that the problem is caused by fixture and not the data

[Ynot]

[I think you'll find that the OP said the faulty fixture was the fourth in a line of 4, so unfortunately that logic doesn't quite compute.

 

Actually he also said the line continues on to control other items which continue work without any problems.

 

Which suggests that the data line is clean and that the problem is caused by fixture and not the data

whoops, my bad.

Apologies.

[jfitzpat]

I'd go with checking the cabling (by substitution perhaps) first...

 

As pointed out above, the XLR connectors in the units (like many DMX fixutres) are wired directly together. Since downstream items are working (see the original post), the problem is almost certainly either power, or inside the 4th unit itself. That is, a cable problem is unlikely, since the same cable is providing signal to other equipment.

 

-jjf