Linking Zero88 Level12 to Polaron dimmers

[karl]

A local amateur company have just been given a Zero88 Level 12 desk to replace their knackered old desk. They have also been given three Polaron LL-4PA dimmers. The desk looks almost brand new and the dimmers look totally unused.

 

The Level 12 has two 8 pin DIN connectors but the dimmers have Sub-D connectors. The dimmers come with a 'manual', consisting of 4 photocopied pages, which gives the layout as pins 1-4 channels 1 to 4, pin 12 power out +20V 150ma and pin 15 0V common.

 

The desk has two 8pin DIN sockets each of which has pins 1-6 carrying channels 1-6, pin 7 is for a supply voltage (+ 20V 85ma) and pin 8 as 0V.

 

Am I right in thinking that there aren't going to be standard cables available to link these? If not how would one go about connecting this lot up?

 

What confuses me is the fact that the dimmers are 4 channel so there are three of them and two 6 channel connectors on the desk. Presumably channels 1-4 on the first 8pin DIN go to the first dimmer, channels 5 & 6 then go to the second dimmer along with channels 1 & 2 from the second 8pin DIN and finally channels 3-6 on the second 8pin DIN go to the third dimmer. But what about the 20V feed and the 0V reference?

 

Any advice will be very much appreciated.

[tom_the_LD]

Were the dimmers and desk given seperately or where they from the same source? If the same source then it may be worth contacting them and asking how they did it previously.

 

However it's worth noting that 6 channels on a dimmer is usually 'standard' - I'm thinking most cases here guys. Betapacks, tempus, mini 2 that kindof stuff.

 

I'm also curious to know about the 20v feed for those in the know!!

[bruce]

The 0V reference will be commoned inside the desk.

 

You probably only need to connect up one of the +20 supplies - I'd go for the one on plug 1-4

 

The wiring on the 1-4 and 9-12 plugs should be obvious - on the 5-8, connect the 0V on the dimmer to either of the 0V outputs from the desk.

[boatman]

Get a small plastic project box, large enough to hold a small chocolate block (you'll need 14 ways in total) and do the wiring in there. First check with a meter that the +20V input pins on the desk are commoned, then use three diodes to isolate the +20V supplies (from the dimmer packs) from one another and connect them to a common +20V bus in the project box. That way if one of you dimmer packs decides no die you'll still have +20V from the other two to supply the desk.

 

I'll draw a sketch later if you wish but it won't be until this afternoon.

[JimWebber]

(Snip)

 

I'm also curious to know about the 20v feed for those in the know!!

 

Ouch!!!!!! I do feel old now, thanks Tom!!!!!!!!!

 

Way, way back in the days of lore, most lighting desks had no seperate power supply - The Level 12 being discussed here was from an era before memory desks were the norm, and DMX was merely a twinkle in the USITT's eye... The only way such two preset desks could receive power - for voltage reference, and the timing circuits - was via the dimmer pack - hence the 20V feed above.

 

In these modern enlightened times, most desks plug into the mains, and derive their own reference and control supplies. (The same goes with Demuxes) Therefore the +V supply from the dimmer pack is normally unused.

 

HTH

 

Jim

[karl]

However it's worth noting that 6 channels on a dimmer is usually 'standard' - I'm thinking most cases here guys. Betapacks, tempus, mini 2 that kindof stuff.

 

I'm also curious to know about the 20v feed for those in the know!!

There are a number of dimmer packs that have 3 or 4 channels, such as Alphapacks. As Jim says the 20V powers the desk so it doesn't have a separate power supply.

 

 

The 0V reference will be commoned inside the desk.

 

You probably only need to connect up one of the +20 supplies - I'd go for the one on plug 1-4

Thanks, that was what I wasn't sure about I'd worked out that all three 0V would have to be connected to the desk but I wasn't sure which DIN socket the middle dimmer should go to (or whether it should be both). If they are common then that's easy enough.

 

Also, I was unsure if the middle dimmer's 20V line should simply be left disconnected.

 

Get a small plastic project box, large enough to hold a small chocolate block (you'll need 14 ways in total) and do the wiring in there.

That's exactly what I had in mind.

 

First check with a meter that the +20V input pins on the desk are commoned, then use three diodes to isolate the +20V supplies (from the dimmer packs) from one another and connect them to a common +20V bus in the project box. That way if one of you dimmer packs decides no die you'll still have +20V from the other two to supply the desk.

If they aren't commoned then do they need to be fed from separate dimmers?

[PaulDF]

If they are not common then you will need to feed them both from the 20v BUS in the project box.

[tom_the_LD]

Sorry Jim I should have been clearer!

 

I ment why the dimmer gives off 150mA at 20V and the desk takes 85mA at 20V - as in why is it they're not the same?

[karl]

Sorry Jim I should have been clearer!

 

I ment why the dimmer gives off 150mA at 20V and the desk takes 85mA at 20V - as in why is it they're not the same?

The 85mA is what the desk draws the 150mA is what the dimmer is capable of supplying. So long as the draw is less than the maximum available, which it is, everything is fine.

 

Many thanks to all who've responded. I think I've got my head around it now.

[boatman]

Sorry, been busy today and I only just got chance to do this:

 

  +20V from dimmer 1 ---->|---o----o-----o--- +20V to desk socket 1
						  |		  |
						  |	o	 |
 +20V from dimmer 2 ---->|---o		  +--- +20V to desk socket 2
						  |	o
						  |
 +20V from dimmer 3 ---->|---+	o

							   o
							   .
				  Chocolate block connections
							   .
							   o

			 GND --------------o--------- GND
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