Chroma Q scrollers with a Fat Frog, Having DMX problems Options

[Jamtastic3]

Hi to all,
Having a problem at college with 4 Chroma Q scrollers with a Fat Frog desk. We can't seem to get any DMX signal through to the scrollers yet we have properly daisy chained the signal and assigned the adresses as well as assigning the 'fixtures' into the board itself, but nothing seems to be happening. We know power is going to the scrollers as the fans inside turn, and their is a signal from the 5 pin output to a 5 pin to 4 pin converter box (not sure about the specs of this). Could it be that the scrollers simply haven't been assigned properly (we are sure they have) or is there anything to do with phase reversals or a problem at the converter?
I have to ask here since my tutor has forgotten how DMX works, never mind getting 4 scrollers to work!

[gareth]

The "5 pin to 4 pin converter box" is actually the power supply for the scrollers - you stuff mains and DMX512 into it, and it sends DMX and 24vdc to the scrollers. This has a "Data" indicator on it - is that lighting up when you switch on the power and connect the PSU to the Fat Frog? If not, your problem lies upstream of here.

If it dies light up, have a look at the underneath of the scrollers - you'll see three LEDs. The red one lights up when there's power getting to the scroller. The green one lights up when it's receiving DMX. The yellow one varies in intensity depending on the DMX value being received by that scroller. Have a look at what those LEDs are doing. If there's no red LED, you have no power to your scrollers - check that you've plugged everything in, and check the continuity of your cables. If you have a red one but no green one, there's no DMX to the scroller - if you've already checked that there's DMX at the PSU, then the most likely cause is an open-circuit fault on the data pins somewhere in one of your scroller cables. If you have a red one and a green one, waggle the DMX channel that you think your scroller is addressed at, and the yellow LED should go on and off - if it doesn't, check the address setting on the scroller, and check the softpatch in the control desk.

[Stu]

Have you got the green LED lit up on any of them? If not, this'll indicate a lack of DMX data to the scrollers. Try testing the 4pin cable from the PSU to the first scroller with a meter to make sure all the pins are connected straight through (I.e. 1-1, 2-2 etc) and that there is continunity.

It could be a dodgy cable on the first scroller which is causing an issue.

Also check and double check the patch on the desk - sometimes it's the sillest of little things you miss! Which version of the Chroma Qs have you got? I.e. do they have DIP switches or Radial dials? Double check these are all set as they should be, and addressed properly.

Also try setting the first scroller to 1 (when you know the cable from the PSU to it works aok) and see if you get any joy with it when you use fader 1 on the Frog.

HTH
Stu
PS. Also try downloading the manual from AC Lighting site (use google for the URL )
PPS. Curse you Gareth for having quicker fingers than me...

[Tom Baldwin]

The power supply unit has both male and female 4 pin connectors on it: the female connector is the output, while the male connector is a "return", which terminates the DMX signal passed to the scrollers. Both connectors provide power to the scrollers (to minimise voltage drops in the cable). A common mistake with scrollers is to only cable from the male connector on the power supply to the scrollers - that means they'll get power, but won't get data.
You must cable from the female 4 pin XLR out to the scrollers. You should continue the cable run back to the male 4 pin XLR (although it's not always necessary).

If you've only cabled from the male 4 pin XLR, this will explain the fans turning, but the scrollers not reacting.

Tom

[David Buffham]

The "5 pin to 4 pin converter box" is actually the power supply for the scrollers - you stuff mains and DMX512 into it, and it sends DMX and 24vdc to the scrollers. This has a "Data" indicator on it - is that lighting up when you switch on the power and connect the PSU to the Fat Frog? If not, your problem lies upstream of here.

In this scenario it could also be the PSU box itself. I only mention this because we had a problem with Rainbows a few weeks ago where the PSU wasn't showing any indication on the Data LED with DMX plugged in, though the power led was OK. Also the scrollers were getting power OK but no data. We verified that there was valid DMX on the cable, so figured the PSU was at fault. We got the rental company to send us over another one, and swapping it out cured the problem.

David

[spantax]

Deleted my post due to me providing wrong information!

Spantax
LampettGeneralen


Moderator's note : we've said it before and we'll say it again - if you make a post, and someone then replies to it, do not make any major changes to the original otherwise it just renders the flow of the topic and any replies to the edited post meaningless. On this occassion, the original text of Spantax's post, which he later edited out, is contained in full in Gareth's post immediately below. You can't sweep your mistakes under the carpet that easily, you know!

My intention was not to sweep, my mistakes under the carpet! I simply have not been attending TBR, long enough for me to know about the policy of not deleting posts that has been replied to! I will certainly remember that in the future, should I ever put my foot in my mouth again!
I guess I owe both Tom and Gareth a pint of beer if we ever run into each other! Maybe at PLASA?

[gareth]

Hi Tom,

What exactly are you saying here?
The reason for me asking, is that you seem to contradict yourself a few times..

First you say that it is necessary to run a return line from the scrollers for them to accept DMX ( which is incorrect BTW!) And then in your next sentence, you say that it is not always necessary to do so...?
You then go on to saying that if you only ran a cable from the Male 4 pin XLR this will explain the fans turning and the scrollers not reacting, again contradicting yourself, from the last sentence...

I don't meen to be impolite, and I know how Scrollers work, I just think maybe you should clarify your statements a little bit, because I think they will just ad to the confusion of the initial poster!

Spantax, you need to read Tom's post properly, I think, before you criticise him. What he says is absolutely right, and at no point does he contradict himself as far as I can see.

Tom did NOT say that it is necessary to run a return line from the scrollers for them to accept DMX - what he said was that you need to run a return cable in order to properly terminate the DMX signal, which is 100% correct.

He also said that running a cable only from the male 4-pin XLR on the PSU (the Return connector) would result in the fans turning but no data getting to the scroller - this is also correct, as the return connector has the 0v/24vdc power supply rails as per the output connector, but terminates the DMX signal on the other two pins and doesn't actually output any data.

So I'd guess that you don't actually fully understand how scrollers work - well, not ChromaQs, anyway. The only person who's "adding to the confusion of the initial poster" here is you, I'm afraid.

[spantax]

Hi Gareth,

If My post was considered as criticism, I apologize, that was not my intent at all!

I reread the post and indeed you are correct, I read male connector and for some reason I was thinking female!

I'm of to my corner now, and on my way I will delete my post so that it doesn't add any more confusion!

Spantax
LampettGeneralen