Understanding Touring Dimmer Rack Patch Panels

NateTheRiddler

Well-Known Member
Premium Member
Joined
Dec 27, 2018
Location
Arizona, US
Good morning, CB! It’s time for Newbie Nate’s Question of the Day!

Today, I’ve been studying dimmer racks and modules, in an attempt to get a better electrical grasp of what’s going on in my PAC. One of the things I’ve seen worked on (and mentioned) are “patch panels” (correct me if the term is incorrect) located on the back of touring dimmer racks such as the ETC CEM+/CEM3.

Brace yourself for Pain from Hard Face Palming, please:
How the *&$% do these things work?!?

Now, mind you, I’ve been googling trying to find instructions on how the signal flow works from rack control to those small connectors on the panel, and then from there to the circuit outputs that will eventually become a touring rig of conventionals. Unfortunately, I don’t have a touring rack in my PAC to play with and figure it out on my own. And, lastly, I’ve scoured the forums here and found plenty of technical troubleshooting, but I barely understand the dang thing.

If anyone has an article tutorializing me on how to patch a touring rack, I’d be beyond elated. Of course, if this is one of those RTFM sorts of things, please do point me to the right point in the manual, because I read the entire CEM Configuration Manual and couldn’t find info on it. T_T

Thanks for those of you who took enough Tylenol to answer this post! :)
 
Last edited by a moderator:
  • Like
Reactions: RonHebbard

derekleffew

Resident Curmudgeon
Senior Team
Premium Member
Joined
Aug 21, 2007
Location
Las Vegas, NV, USA
See here: https://www.controlbooth.com/threads/etc-sensor-patch-bay-touring-rack.40366/ .

At the fixture, a light is plugged into one of six circuits on the multi-cable break-out. Let's say the second circuit.
The break-out is then plugged into a Socapex-style multi-cable that happens to be labeled [R1]A.
At dimmer Rack#1, the male end of the soco is plugged into outlet labeled A.
Inside the rack's patchbay, circuit A2's single banana-type plug is inserted into Dimmer#1.
At the console, dimmer#1 is soft-patched to control channel#1.
Bring up channel 1 to full, DMX tells the CEM to bring up dimmer 1 to full.
Electricity flows from the dimmer via the circuit to the luminaire.

Notes:
The hanging cords are the hot conductor s of the circuit s and the jacks are the dimmer outputs.
The pin patch only carries the hot wire; all the neutrals are bussed together inside the rack.
Only the Socapex outlets are patchable. The 2P&G receptacles on the rack are direct to dimmer.

Any questions?
 

NateTheRiddler

Well-Known Member
Premium Member
Joined
Dec 27, 2018
Location
Arizona, US
See here: https://www.controlbooth.com/threads/etc-sensor-patch-bay-touring-rack.40366/ .

At the fixture, a light is plugged into one of six circuits on the multi-cable break-out. Let's say the second circuit.
The break-out is then plugged into a Socapex-style multi-cable that happens to be labeled [R1]A.
At dimmer Rack#1, the male end of the soco is plugged into outlet labeled A.
Inside the rack's patchbay, circuit A2's single banana-type plug is inserted into Dimmer#1.
At the console, dimmer#1 is soft-patched to control channel#1.
Bring up channel 1 to full, DMX tells the CEM to bring up dimmer 1 to full.
Electricity flows from the dimmer via the circuit to the luminaire.

Notes:
The hanging cords are the hot conductor s of the circuit s and the jacks are the dimmer outputs.
The pin patch only carries the hot wire; all the neutrals are bussed together inside the rack.
Only the Socapex outlets are patchable. The 2P&G receptacles on the rack are direct to dimmer.

Any questions?
Wow! :pray: Thanks a bunch! That completely nailed what I was trying to understand about the system.

Only one question, a conceptual one:
I see on the patch bay of the CEM that each dimmer has two “banana-type” sockets (correct terminology???). So, if I took two fixtures, both on [R1]A, and occupied both of the dimmer 1 slots, then those fixtures have been essentially cloned, correct?

Also, as a test of my own knowledge, the signal flow is:
Desk —> CEM —> Selected Dimmer —> Chosen Socapex Circuit via banana-type connector —> Socapex breakout —> Fixture assigned to numeric circuit
 
  • Like
Reactions: RonHebbard

derekleffew

Resident Curmudgeon
Senior Team
Premium Member
Joined
Aug 21, 2007
Location
Las Vegas, NV, USA
Only one question, a conceptual one:
I see on the patch bay of the CEM that each dimmer has two “banana-type” sockets (correct terminology???). So, if I took two fixtures, both on [R1]A, and occupied both of the dimmer 1 slots, then those fixtures have been essentially cloned, correct?
Not conceptual at all. Two fixtures, plugged to A1 and A2 on the break-out and occupying both holes (some racks have four holes per dimmer output; touring racks are very customizable when ordered) of dimmer 1 are said to be "two-fered at the rack" (using two circuits) as opposed to being "twofered at the light" or "two-ferred on the pipe" (using one circuit). I wouldn't use the term "cloned" as that generally means substituting or adding moving lights not conventionals.
Also, the CEM is the removable module that is the rack's brain. It doesn't have a patch bay. The dimmer rack has a patch bay, one CEM (and often an additional spare in a dummy slot), and dimmer modules (also sometimes spares in dummy slots).

Also, as a test of my own knowledge, the signal flow is:
Desk —> CEM —> Selected Dimmer —> Chosen Socapex Circuit via banana-type connector —> Socapex breakout —> Fixture assigned to numeric circuit
That's it! Viola.
 

NateTheRiddler

Well-Known Member
Premium Member
Joined
Dec 27, 2018
Location
Arizona, US
Also, the CEM is the removable module that is the rack's brain. It doesn't have a patch bay. The dimmer rack has a patch bay, one CEM (and often an additional spare in a dummy slot), and dimmer modules (also sometimes spares in dummy slots
Thanks for the terminology corrections; I’ve discovered one of the things betraying my ignorance despite my experience is my poor vocabulary, misusing terms and such. I appreciate the corrections so I can make better communication effort.

That's it! Viola.
Magical! Thanks for the help; guess I’m adding your name to my USITT/LDI “I owe this person a beer” list. :D
 
  • Like
Reactions: RonHebbard

derekleffew

Resident Curmudgeon
Senior Team
Premium Member
Joined
Aug 21, 2007
Location
Las Vegas, NV, USA
Thanks for the terminology corrections; I’ve discovered one of the things betraying my ignorance despite my experience is my poor vocabulary, misusing terms and such. I appreciate the corrections so I can make better communication effort.
Socket. The base is part of the lamp.
Spend as much time as possible in the wiki.
Most people will overlook transgressions such as calling a SourceFour a Leko, bulb/lamp, lectern/podium; but those who know will still judge you for it.

And this is, I think, at the heart of this discussion. We work in an industry dominated by people that use terms incorrectly, often because of a simple lack of knowledge. As professional entertainment technicans, it is our job to know the proper terms, know what they apply to, know the standard "generic" or slang usage of such terms, know the local meanings of such terms, know the assumed or implied meanings of such terms, be able to remember to always ask plenty of questions to decode what the client wants instead of just assuming, AND have enough resources and foresight to be able to cover when the client walks up to you during a set up and asks "I want X".

With these terminology discussion, I think it's my own personal goal, and the goal of most of the CB team, to not always insist that one term is right or proper (althought some are certainly more concrete than others) since we can never seem to agree on some terms, but rather, our goal is to widen the base of knowledge concerning terminology and its usage by discussing both intended and proper use, as well as all other usages. Perhaps we can do our part to help foster correct and proper terminology usage, but really, that dream is still a ways away, and till that day, we will all have to know the slang.
-----

Magical! Thanks for the help; guess I’m adding your name to my USITT/LDI “I owe this person a beer” list. :D
Give mine to @gafftaper or @dvsDave . Or even better, give to Behind-the-Scenes.
 

NateTheRiddler

Well-Known Member
Premium Member
Joined
Dec 27, 2018
Location
Arizona, US
  • Like
Reactions: RonHebbard

dvsDave

Benevolent Dictator
Administrator
Senior Team
CB Mods
Fight Leukemia
Joined
Jan 31, 2003
Location
DC Metro Area
:think: I already owe @gafftaper a full case; don't know if I can afford to make it two xD Guess @dvsDave is going to be the lucky recipient!
@gafftaper doesn't drink, just buy him a couple Diet Cokes and he'll be happy. As for me, just spread the word about CB and get as many people as you know to join and I'll be happy. :)
 

gafftaper

Senior Team
Senior Team
Fight Leukemia
Joined
Jan 2, 2006
Location
Seattle, WA
Ah for the bad old days before we could afford dimmer per circuit systems and every theater came with a patch bay, you would have never needed to ask. I always taught it this way to my students when I had a patch bay.

Definitions:
Channel: The number that the light board identifies for controlling a fixture
Dimmer: The source of power for a fixture
Circuit: The pathway for power to get from a dimmer to a fixture
Channel Number, Dimmer Number, and Circuit Number are not the same thing and are constantly re-patched depending on the needs of a show.

So:
-Turning on Channel #1 on the board can turn on any dimmer depending on how you soft patch it in the light board setup. So let's say we want Channel #1 to turn on Dimmer #32 we go into the patch function on the board and set that up.

-Just because you turned on Dimmer #32 doesn't mean you are sending power to a circuit labeled #32. We use the patch bay to assign a circuit to a dimmer for a source of power. So let's say we want to turn on a fixture plugged into circuit #57. We use the patch bay to connect circuit #57 to Dimmer #32. Depending on the load, the size of the dimmers, and the design of the patch bay, we can often send power to multiple circuits from the same Dimmer. Lets say you have fixtures plugged into Circuits #17 and #123 that you want to turn on and off with #57. If their combined load doesn't exceed the capacity of the dimmer, you can patch all three of them to dimmer #32. So let's say The dimmer is a 2.4k dimmer and we have a 750 watt Source four on each circuit. We can patch all three circuits to the same dimmer.

When we are done, when we turn on Channel #1 on the board, Dimmer #32 turns on, and the fixtures plugged into circuits #17, #57, and #123 all turn on together.

Today most theaters have Dimmer Per Circuit systems where a dimmer is hardwired directly to a circuit and there is no possibility of repatching. But older theaters and touring shows still often have patching capabilities.

@derekleffew it's been a few years since I gave that lecture did I make any mistakes?
 

gafftaper

Senior Team
Senior Team
Fight Leukemia
Joined
Jan 2, 2006
Location
Seattle, WA
@gafftaper doesn't drink, just buy him a couple Diet Cokes and he'll be happy. As for me, just spread the word about CB and get as many people as you know to join and I'll be happy. :)
If it's full of fruit, or ice cream and college girls drink it, I might like it.
 

NateTheRiddler

Well-Known Member
Premium Member
Joined
Dec 27, 2018
Location
Arizona, US
Ah for the bad old days before we could afford dimmer per circuit systems and every theater came with a patch bay, you would have never needed to ask. I always taught it this way to my students when I had a patch bay.

Definitions:
Channel: The number that the light board identifies for controlling a fixture
Dimmer: The source of power for a fixture
Circuit: The pathway for power to get from a dimmer to a fixture
Channel Number, Dimmer Number, and Circuit Number are not the same thing and are constantly re-patched depending on the needs of a show.

So:
-Turning on Channel #1 on the board can turn on any dimmer depending on how you soft patch it in the light board setup. So let's say we want Channel #1 to turn on Dimmer #32 we go into the patch function on the board and set that up.

-Just because you turned on Dimmer #32 doesn't mean you are sending power to a circuit labeled #32. We use the patch bay to assign a circuit to a dimmer for a source of power. So let's say we want to turn on a fixture plugged into circuit #57. We use the patch bay to connect circuit #57 to Dimmer #32. Depending on the load, the size of the dimmers, and the design of the patch bay, we can often send power to multiple circuits from the same Dimmer. Lets say you have fixtures plugged into Circuits #17 and #123 that you want to turn on and off with #57. If their combined load doesn't exceed the capacity of the dimmer, you can patch all three of them to dimmer #32. So let's say The dimmer is a 2.4k dimmer and we have a 750 watt Source four on each circuit. We can patch all three circuits to the same dimmer.

When we are done, when we turn on Channel #1 on the board, Dimmer #32 turns on, and the fixtures plugged into circuits #17, #57, and #123 all turn on together.

Today most theaters have Dimmer Per Circuit systems where a dimmer is hardwired directly to a circuit and there is no possibility of repatching. But older theaters and touring shows still often have patching capabilities.

@derekleffew it's been a few years since I gave that lecture did I make any mistakes?

I'm pleased to announce for the first time I actually understood that 100%, thanks to derek's and your explanations. Applause for having that scenario able to ready, aim, fire.
 
  • Like
Reactions: RonHebbard

BillConnerFASTC

Well-Known Member
Joined
Jan 30, 2010
Location
Clayton NY 13624

gafftaper

Senior Team
Senior Team
Fight Leukemia
Joined
Jan 2, 2006
Location
Seattle, WA
Does anyone have a picture of an old slider style patch panel? It might be an interesting addition to this story, but I hesitate to try to explain one without a picture.
 
  • Like
Reactions: RonHebbard

JD

Well-Known Member
Joined
Jan 1, 2005
Location
North Wales PA
When I first got into lighting, 6k dimmers were very popular. It was less expensive to have a few larger dimmers than a lot of smaller ones. The patch panel was standard. You might have five or six circuits going to different locations patched on to one dimmer. Between scenes, there was often a scramble to repatch. The picture I found below is very reminiscent of those days. Each dimmer would have 5 sockets and you would patch your circuits into it. Often, a theater may only have 36 dimmers. By the time I retired, most was "Dimmer per circuit" so the patch panel was a thing of the past. Still, there is a place for this in touring due to the desire to have 6 circuit Socapex connectors on the rack, and the need to assign them to common 2k dimmers. So, what's old is new again! ... for now.
patch-panel.jpg
 
  • Like
Reactions: RonHebbard

gafftapegreenia

CBMod
CB Mods
Joined
Sep 24, 2005
Location
Michigan
I don’t have a picture of the Electro-Controls slider patch still in use in the TV studio at my alma matter, but I do have this 1966 Century install I’m working with this month.
5DE7764A-1BC1-4CB4-9264-E87FEDE3476A.jpeg

94FC7485-F75A-4DC4-BE25-2419D6AAAA31.jpeg
 

derekleffew

Resident Curmudgeon
Senior Team
Premium Member
Joined
Aug 21, 2007
Location
Las Vegas, NV, USA
Does anyone have a picture of an old slider style patch panel? It might be an interesting addition to this story, but I hesitate to try to explain one without a picture.
https://www.controlbooth.com/threads/just-for-curiosity-and-discussion.32306/#post-284683


https://upload.wikimedia.org/wikipedia/commons/thumb/c/cd/ECpatchbay.JPG/220px-ECpatchbay.JPG

Since both slider and telephone patch panels are obsolete (but pin patch is not) I hesitate to throw too much at Nate at one time (or ever). All yall's doing now is showing your age.
-----
@derekleffew it's been a few years since I gave that lecture did I make any mistakes?
Everything sounds correct, but I again question why even bring it up. Odds are Nate is either going to be working with a DPC installation where dimmer and circuit can be used interchangeably, or with all portable dimmer rack s / dimmer pack s.
 
  • Like
Reactions: Jay Ashworth

RonHebbard

Well-Known Member
Premium Member
Joined
Jun 12, 2004
Location
Waterdown, ON, CA
  • Like
Reactions: macsound

gafftaper

Senior Team
Senior Team
Fight Leukemia
Joined
Jan 2, 2006
Location
Seattle, WA
@derekleffew there are still a few community theaters out there with patch panels. Not a lot, but some. I have always liked teaching the concept because it helps to understand the possibilities and joy of repatching your console, it also helps to teach good discipline with loads for circuits, and it prepares you to deal with a touring patch panel.

So, @NateTheRiddler see that picture Derek posted. It's a series of sliders that lock into notches as you slide up and down. Each notch represents a dimmer Each slider is a circuit. So you had to watch your load math and make sure you didn't assign too many circuits to the same dimmer notch and blow a breaker. It was pretty cool but at some point in the 80's probably the cost of dimmers came down enough that it made more sense to just go dimmer per circuit.
 

JohnD

Well-Known Member
Fight Leukemia
Joined
Jan 11, 2012
Location
north central OK
Then there were the Kliegl patch options:
ROTOLECTOR
Then there was the SafePatch telephone exchange style unit. Unlike the Century one shown above the Kliegl had either a toggle switch or perhaps a circuit breaker mounted below or beside each hole. If you were unpatching a circuit when you pulled out the plug it tripped the switch off. When patching you inserted the plug and flipped the switch back on(it could be done one handed).
SAFEPATCH
 
Last edited:
  • Like
Reactions: RonHebbard

danTt

Well-Known Member
Joined
Aug 24, 2011
Location
NY
Also, the CEM is the removable module that is the rack's brain. It doesn't have a patch bay. The dimmer rack has a patch bay, one CEM (and often an additional spare in a dummy slot), and dimmer modules (also sometimes spares in dummy slots).

That's it! Viola.
Of course, it's possible to add an additional layer of patch/translation at the cem level, but 95% of the time it's pure evil To do so.
 
  • Like
Reactions: RonHebbard

Users who are viewing this thread