DMX Y split inside Soundlab Dimmers

[osal]

Hi guys I know that DMX y splits have been discussed on here a lot.

however I have just been to have a look inside I faulty sound-lab 4 ch dimmer and I noticed that the DMX is just y split inside, to DMX out and then then the board. just wondered if anyone else had come across this?

 

http://img29.imageshack.us/img29/8972/dscf0334w.jpg

 

I know this image isn't very clear but hopefully you will see.

[Ynot]

You'll find that's how a lot of kit - even higher end - is wired.

Because it's so close to the actual DMX decoder circuitry, the problems you'd encounter with an external wired split won't be there.

[osal]

I thought it would be something like that. signal not having far to run but I just thought I would ask the question. Yeah I had seen it in other kit but was sat here working my way through repair equipment I thought I would mention it.

Cheers for the response

[peternewman]

There is a maximum tee length defined in the standard, I've got 80mm in my head, but that might well be entirely made up. Anyway there is a length below which its within spec to have a passive split.

 

IIRC the standard also says a depowered fixture shouldn't affect the rest of the line, which makes sense. So if you had an active split you'd still need some relays to switch back to pass-through when the fixture loses power. As Tony said, this method is pretty standard and is the obvious way to go. Which is also why you shouldn't use both the 3 and 5 pin outs from fixtures that have both, use a splitter instead.

[TomHoward]

I was about to comment that I see you've reversed the polarity on that one already (as you can see a piece of the pin header has been cut off) until I realised that it's my image. Pin 2 and 3 on the DMX input is reversed on these things, that's something to check you've considered as well - as the DMX light will still light without a reversed input but the channels won't work.

 

Also to mention that on the one pictured there wasn't anything connected to that second pin header - the parallel split was done between the XLR sockets and didn't go through the board.

[osal]

I was about to comment that I see you've reversed the polarity on that one already (as you can see a piece of the pin header has been cut off) until I realised that it's my image. Pin 2 and 3 on the DMX input is reversed on these things, that's something to check you've considered as well - as the DMX light will still light without a reversed input but the channels won't work.

 

Also to mention that on the one pictured there wasn't anything connected to that second pin header - the parallel split was done between the XLR sockets and didn't go through the board.

 

yeah cheers I was in on the original post when you posted the picture. already phase reversed them the dimmer pack was placed on the flour running some floor cans when somebody stood on the XLR needing the socket to be re soldered.

 

but thanks for the heads up on the phase rev unfortunately my versions of these packs are PCB mounted so a slightly longer job I will get round to doing at some point as it really dose drive me mad

 

I prob noticed the y split then but never thought of mentioning it