Control/Dimming Bleeding Circuits/crosstalk

[agenson]

My school has a Strand LBX and two of the circuits "115 + 116" bleed into each other. It just happens that 115 is blue and 116 is red. When I tell the board "115 ON" it puts up 115 and 116 ON. It doesn't say on the screen that 116 is on, but you can see it on stage, it's magenta. So going up to the dimmer rack, I flip off 115, and 116 still remains on. And everything vice versa (116 ON, flip 116 off, 115 still on). What do you think is wrong and what can I do about it? I've tried switching out for new dimmer packs and that doesn't solve it.

Also, where can I get a copy of Kaleidoscope and a Remote for the LBX? It's so old STRAND doesn't have it anymore. Thanks!

 

[Esoteric]

Have you tried (after backing up!) resetting the console and cleaning out the pots? Check your DMX line. Also get an electrician to check the break out to the circuit box to make sure that a wire isn't getting crossed.

Mike

 

[derekleffew]

...I've tried switching out for new dimmer packs and that doesn't solve it. ...

Does this mean the problem still exists with a known good working dual dimmer module? I have experienced similar crosstalk with an original CD80 module. If the problem exists with a known good module, the problem is either in the processor or the wiring. Highly doubtful it's the console.
Exactly what model are the dimmers? I'm guessing CD80AE.

 

[Esoteric]

Does this mean the problem still exists with a known good working dual dimmer module? I have experienced similar crosstalk with an original CD80 module. If the problem exists with a known good module, the problem is either in the processor or the wiring. Highly doubtful it's the console.
Exactly what model are the dimmers? I'm guessing CD80AE.

Wiring was my initial thought. But it doesn't hurt to check out the console.

Mike

 

[itie]

i did a show in a theatre with ghosting lights and the T.D. tried resetting the brain in the dimmer rack maybe that might help. but ghosting and crosstalk are two different problems.

 

[JD]

Ghosting and crosstalk usually means you get some residual out of an adjacent channel. This sounds more like they are working in lockstep together. I would agree with Derek that this may be either a backplane (wiring) problem, or a dimmer control module problem. Hard reset of dimmer control mod may help. Address tables in dimmers control mods are usually in RAM, so they can get corrupted.

 

[David Ashton]

I would suspect a short between the 2 control leads in the rack

 

[Esoteric]

I would suspect a short between the 2 control leads in the rack

Each dimmer has control leads (as in wires) in the CD80?

Mike

 

[waynehoskins]

If it only affects these particular dimmer slots, and predictably at that, here's what come to mind:

- Does LBX have a channel hookup table?
- I don't remember if AE racks have adjustable address tables on their firing cards or not, but if so, check that.
- Reset the firing card; sometimes memory goes flaky, and that memory is old now.
- Is the rack dirty? Dust does funny things to high-speed circuits and chips that run fast ( = warm).
- You could have either excessive crosstalk in the PWM lines going from the firing card to both sides of slot 10 in rack 2 (presuming you're all 2.4s, no 6Ks or 12Ks), or even continuity between them.

I would seriously look first at the channel hookup and then at the rack address table if there is one. I'll readily admit to not being terribly familiar with the CD80 racks and the LBX console, but looking quickly at Strandarchive, Lightboard/X is comparable to Express/4896, so no doubt there's a softpatch in there. Let that be the very first place you look.

Edit: I just realized that the racks being CD80, let alone AE racks, was somebody's hypothesis, not definite reality (though quite probable). The principles apply to any PWM rack, but again, I think the rack is fine.

 

[David Ashton]

With a dmx tester this problem can be resolved in 5 minutes but trying all the different hypotheses on this thread could take a long time, I think getting a technician in is the way to go, especially if I'm right and the fault lies in the dimmer.

 

[lightman02]

Kinda strange it only happens with those two dimmers, usually when a firing card is going bad you see more issues then just two dimmers having issues but I guess every thing's possible. Also of course check all patching, it almost seems like you have a patching issue. Also what dimmer rack do you have cause unless I read wrong, you never stated what kind of rack you have???? Some dimmer racks can hold a sperate patch, please let us know the dimmer rack brand and model.

 

[agenson]

Yes it's the CD80, I'd have to check back to see if it's the AE. 115 and 116 are in the same pack, and the problem still happens with a known good pack. I will definetly look into the crosstalk. Thanks!

EDIT: CD80SV

 

[lightman02]

Yes it's the CD80, I'd have to check back to see if it's the AE. 115 and 116 are in the same pack, and the problem still happens with a known good pack. I will definetly look into the crosstalk. Thanks!

Can you switch firing card from pack to another to verify if its the firing card or something else. If you switch firing cards and it still happends I would say it's the board patch most likely.

 

[David Ashton]

And the most obvious fault is still a short between the two control wires in the rack.

 

[lightman02]

And the most obvious fault is still a short between the two control wires in the rack.

True, actually one very simple thing to try is to just reseat the firing card, you'd amazed how many times that actually works. Sometimes dust and dirt gets in the connections and can create a short or nother issues.

 

[agenson]

Ok, one more vital piece of information is that I manually moved the fixture that was on 115 to "132" (not that is matters), then if I tell my board to (digital) patch 132 as 115, 116 still comes on! It's very strange. But if I just tell 132 ON, it's fine. So it's very messed up. x] Thanks again.

EDIT: I can patch it as ANYTHING except 115 and it will be fine; 132 @PATCH 1, 1 ON = it works fine. 132 @PATCH 115, 115 ON= 132 and 116 ON.


And I finally got a hold of STRAND and they redirected me to a "Vincent Lighting" Manager, and we've been exchanging emails. He says,

"As for the crosstalk between a pair of dimmers, it sounds like one of the panic dual diodes is shorted. The simple solution is to set the panic dip switch on the CIC board (the PCB on top of the control electronics crate) for the affected dimmers to off."

Can anybody on here help explain to me, what he's talking about? I have no idea what the CIC board or what a PCB is.

Thanks!

 

[Darthrob13]

You might consider getting someone in to help you. These are simple things, but can have a serious impact on the life of the rack and on the life of the user (if you're not careful).

If you don't know these things, then it's time to learn. From someone who knows. In the same room with you.

 

[waynehoskins]

So to make sure I've got it straight:

Earlier, the two affected lights were plugged into holes 115 and 116, which are hardpatched to dimmers 115 and 116, which are responding on DMX addresses 115 and 116 and patched to console control channels 115 and 116.

You've now replugged the light that was in 115 into hole 132, on dimmer 132. To make that show up where you want it, you softpatched address 132 onto handle 115.

Two questions:
- Did you ever unpatch dimmer 115 from channel 115?
- If you run up handle 116, does the light that's plugged into hole 116 turn on?