Zero 88 Alpha Pack

[smyles]

Hi all, I've been setting up a local schools lighting system for them, but I am having trouble with 2 of their zero 88 alpha packs. 3 of them are running perfectly which are all DMX, but the other 2 are analogue. these are running through a demux, but I can't get them to respond to the desk.

- the demux is showing up that there is signal on the channels

- the packs respond to the sliders on the packs themselves.

- I have tried different leads

Can somone help me, their performance is next week.

 

Thanks

Myles

[bruce]

Is the demux set to the correct start address?

Do you have the right sort of cables?

 

has it ever worked in the past?

 

I'd be starting by checking the demux settings, then getting a voltmeter and making sure the analogue outputs are as you'd expect.

[pritch]

Have you looked at the bottom of the packs? There's a switch that selects between using channels 1,2,3 and 4,5,6 on the input connector. Change that over - any better? How's the second pack run, using a cable from the outlet on the first pack, or direct from the demux?

[smyles]

Wow quick replies. Thanks

I've tried I on different start addresses but still wont work, as for the switches on the bottom, I had them daisy chained, one on 1,2,3 the other 4,5,6, and then tried individually, and no combination seemed to work.

I will take a voltmeter with me tomorrow to check.

The demux, normally runs 3 old strand dimmer packs and runs fine with them, have tried a different demux aswell.

I have been it all worked last time they were used, but it is possible that could have been 2 years ago

 

Myles

[ocfe]

What demux are you using?

As you say the demux normally runs old strand dimmer racks does it send out 0 to -10v?

The Alpha pack will want to recieve 0 to +10v

 

What demuxes are available for use?

[maeterlinck]

Old stand stuff used the opposite polarity. So -10VDC instead of the more common +10VDC

(I have got that the right way round haven't I - I'm having a small mental block...

I didn't - but I've now changed it...)

 

Anyways, the point stands that this might be the source of your problem. Where did the other demux come from? If you're luck there might be an inversion switch on the demux, otherwise you're in the realm of another unit to convert the voltage or a different demux.

 

 

Edit: Correct my error

[Neil Hampson]

If it's a Zero88 Demux48 (the Grey one), then the voltage convertor was a seperate option that bolted in, that was bought per 24 channels, as there was only 3 Strand dimmers, there is a very good chance that output channels 25-48 are still +ive voltage out. try plugging the Alpha pack into 'rack 5' using channels 25-27 (start address001)

Other things to look out for, even if the Demux is cabaple of +ive out, check the cabling, the old strand stuff used the chassis connector for ground, most other dimmers use pin 8

[PaulDF]

Try using a DC digital volt meter on the cable where it connects to the alphapack, I'm more familiar with betapacks but the principle should be the same.

On the 8 pin DIN plug from the Demux place the red probe onto pin 1 and the black onto pin 8 (gnd). When you raise the power for channel 1 you should see the voltage increase from 0v eventually to +10v.

Channel 2 check between pin 2 and pin 8 (gnd)

Ch3 = pin 3

Ch4 = pin 4 and so on.

[smyles]

Thanks for all the posts. The problem was indeed the polarity, the Alpha's wanted +10V. One of our demux's had an option to set the polarity so all working. Thanks again for everyone that helped.

 

Myles

 

 

 

Edit: typed the wrong polarity (oh dear, can tell I'm tired ;) )