Dimming Problem

[tommulliner]

Hi Users,

 

I have a problem at school in relation to dimming. I was only in there monday, and was all working fine, but I went to the hall today, switched on the dimmers and the desk (smartfade ML) and was trying to bring up lights, but nothing would come up. I looked at the dimmers and they said that the desk was telling them to put up lights but everything was cleared on the desk. Moved the desk to another possition where there was a DMX feed, and loads of lights came on, with the desk's outputs still at nil.

 

The dimmers are Contractor 24 - dimming and switching pack (harwired) and we use a Smartfade ML.

 

Any help would be much apreciated. Was going to contact our hire guy, but thought would come on here first incase of some silly mistake - but I can't figure it out.

Thanks,

Tom.

[GregB]

I'm not totaly sure I've understood whats going on but it sounds like your dimmers have held recent DMX data from the desk out-put.

To diagnose this more acurately you might try to zero all output DMX at the desk, leave switched on, turn off your dimmers, and then back on. This should leave you in the dark! and help identify if the problem is really at the dimmer, in the DMX or in the desk?

Hope that helps.

[tommulliner]

Have tried resteting, clearing, setting all outputs to nil, yet the dimmers are still putting up lights. There is a data feed to the dimmers.

[jonathanhill]

What happens when you unplug the DMX from board, and then reset the dimmers?

 

e2a: sense

[timmeh2]

Hi

 

Total shot in the dark but I have known some dimmers to go 100% on all channels if you send +5v DC down the DMX line.

 

This is certainly true of Pulsar datapaks.

 

An idea would be to plug the desk straight into the DMX input on the dimmer to discount a cabling or transmission issue.

 

All the best

Timmeh

[tommulliner]

I've got the dimmers working :P , Firstly, I pluged the desk into the dimmers and did a hard reset of the desk. Worked fine, so went to the 1st DMX feed (stage right) and the dimmers behaved the same way as I described before, so I thought, here we go again. I took the desk upstairs(balcony), 2nd DMX feed, and the dimmers worked fine, yet you have to physically conect the first feed to the second to be able to get the feed from the dimmers, that confused me... :)

 

(come to think of it, my post probably confuses you too!)

[dave_m]

What you're describing sounds like a DMX loop through plate, which is actually quite common in many venues. They're put in place to minimise the amount of cabling and processing required in a system.

 

Good thing you worked it out for yourself though.

[osal]

I've got the dimmers working :D , Firstly, I pluged the desk into the dimmers and did a hard reset of the desk. Worked fine, so went to the 1st DMX feed (stage right) and the dimmers behaved the same way as I described before, so I thought, here we go again. I took the desk upstairs(balcony), 2nd DMX feed, and the dimmers worked fine, yet you have to physically conect the first feed to the second to be able to get the feed from the dimmers, that confused me... ;)

 

(come to think of it, my post probably confuses you too!)

 

you haven't got a cross over somewhere have you?

[tommulliner]

What you're describing sounds like a DMX loop through plate, which is actually quite common in many venues. They're put in place to minimise the amount of cabling and processing required in a system.

 

Good thing you worked it out for yourself though.

 

Thanks, although, I dont see how I can use the desk in one place and I can't in another, yet they are conected.

[tommulliner]

Does anyone have any ideas why this is?

[Tomo]

Does anyone have any ideas why this is?

Draw a diagram of how the cables run and the connections between them.

Then someone may be able to help - unless the guy who did the installation reads this, nobody else can know how it was built.

 

The diagram may even answer your question on its own.

- I find that drawing complex systems out on paper is a great help to understanding how everything fits together - and where any problems may be.

 

The 'classic' DMX-loop-thru multi-plugin point system has a single data path, built by fitting several DMX plugin points along one cable.

 

At each plugin point (except the furthest away from the dimmers), there is a female and a male XLR which are normally connected together using a short (preferably captive) patch cable.

Disconnecting the male from the female disconnects everything further away from the dimmers.

 

So they all need to have their male connected to their female to use the furthest-away point.

 

To use a closer point, you disconnect the male from the female and plug your console into to male - thus all the 'upstream' cable is totally disconnected, and you've just got a shorter cable.