Troubleshooting Weirdness

[rochem]

I’ve been fighting with a weird troubleshooting issue for a few days now, and today I finally had some time to really work on it – and I’m super confused as to what’s going on.

So here’s the situation: I’m working with an entirely rented rig, not passing through any house circuits or dimmers or anything – everything is from the shop. I have a pair of Mini-10 500w worklights on 3 different electrics that pass through the rack and down to a switch box on stage. The worklights run through mults to the racks, banana jump out of the rack and into a Worklight breakout, then pass through a second mult down to the stage where they break in into the switch box. The switch box itself has 6 switches spread across 2 circuits (1 thru 3 on one circuit, 4 thru 6 on the other), with two individual circuits powering the switch box running from two hot pockets in the touring rack.

We did about an hour of troubleshooting, testing every component in the lengthy signal chain, and worked our way back to the switch box. After screwing with the switch box for a while, we determined that:

1. Using known hot power, each circuit on the Worklight breakin at the switch box works properly.
2. Both of the circuits feeding the switch box are working.
3. Using the 2E Worklight circuit, the lights came on when plugged into each of the 6 switches on the switch box.
4. Using the 4E Worklight circuit, the lights came on when plugged into each of the 6 switches on the switch box (same result as with the 2E).
5. Using the 6E Worklight circuit, the lights came on when plugged into switches 1 through 3, but did NOT work when plugged into switches 4 through 6.
6. By plugging the 6E Worklight banana jumper into a different circuit on the Worklight mult, everything works fine - the problem only occurs when the 6E Worklights are running on WKLT-6.

Naturally, I'm led to believe that it's a problem with the second hot circuit. But I can't fathom any reason why a circuit would power some lights, but not others. We've swapped out every component (2 mult runs, 2 breakouts, 1 breakin, and the banana jumper) with known good components, and as far as I can tell, it must be something upstream of the Worklight breakin at the switch box. We've solved the problem by plugging WKLT-2 into the 6th switch, and vice versa, but now I'm dying to know how this could even be possible.

Anyone have any thoughts? Thanks!!

 

[meatpopsicle]

When you say banana jump, you mean your coming out of the patch bay on and extended patch cable. Are you only moving the hot?

 

[derekleffew]

I'm going to guess you have TWO causes that only present the one symptom when 6E is plugged to Wrklt 4-6 (or now, using a different circuit, only into Wrklt 6). I suspect a hot-neutral reverse, or maybe a neutral/ground reverse, or both, somewhere. Suspect 6E two-fer and feed for Wrklt 4-6 switches.

Inventive solution for the end goal, but perhaps the lesson to be learned is rather than all this jumping in and out of the patchbay and multi-cable s, it might have been better to just run a long, single 12/3 cable to each electric. Probably more "legal" also.

 

[gafftapegreenia]

So wait, what is the purpose of the rack? Am I correct in understand this switch box of yours only switches the hots?

 

[rochem]

I'm going to guess you have TWO causes that only present the one symptom when 6E is plugged to Wrklt 4-6 (or now, using a different circuit, only into Wrklt 6). I suspect a hot-neutral reverse, or maybe a neutral/ground reverse, or both, somewhere. Suspect 6E two-fer and feed for Wrklt 4-6 switches.

Inventive solution for the end goal, but perhaps the lesson to be learned is rather than all this jumping in and out of the patchbay and multi-cable s, it might have been better to just run a long, single 12/3 cable to each electric. Probably more "legal" also.

Yeah, I was pretty confident that there must be at least two separate issues at play. The G-N or H-N swap seemed unlikely because we swapped out both of those components. Although since you brought it up, I suppose it is possible that the switch box from PRG came with the 4-6 input reversed.

I'm aware that jumping out of the patch bay isn't really advised, not to mention the questionable legality, but I see them get used all the time to great effect. I've done other similar shows where I've run a 2x stage pin cable to the electric for worklights, but for many reasons, running on spare circuits on the mults made more sense than running a bunch of 2x150' 2P&G bundles all across the theatre.

So wait, what is the purpose of the rack? Am I correct in understand this switch box of yours only switches the hots?

Nope. For the worklights, the dimmer racks just act as a passthrough. The banana connectors used in the Sensor pin patch have both hot and neutral, and a circuit is completely unpowered until you plug it into one of the dimmer receptacles in the pin patch. For the worklights, instead of patching into a dimmer, you just plug it into a banana plug female to 2P&G male cable, then run that somewhere else to where it actually gets power. By jumping out of the pin patch, you save the need to run separate cables to each pipe just because they're not being powered by the Sensor racks. We're also doing this for one or two cue lights, and I've also used them in the past for moving lights to jump into the ML distro without having to run another cable to the electric (only when using 120V).

 

[derekleffew]

...Am I correct in understand this switch box of yours only switches the hots?

The vast majority of 120V switches only interrupt the hot wire. I'm sure you knew that.
Rochem, is your switchbox like this?

Switch Box - Female Stage Pin 6-Way | Used Lighting - Used Stage & Theatrical Lighting Equipment, LED Lighting, Trussing

...The banana connectors used in the Sensor pin patch have both hot and neutral, ...

Is this a new or non-standard Sensor Touring Rack? If so, could you please post pictures of its patchbay? All the ones I've ever seen resemble this .

 

[gafftapegreenia]

Yes derekleffew, I should have been more specific. It sounds as if rochem is only running the hots to the switch box, and thus there are neutrals in two separate places, and thus likely two separate circuits.

I have never seen a Sensor rack with a jack such as this:

 

[rochem]

Nope, you guys are right. I was posting rather quickly and didn't really think about what you actually asked, and then I for whatever reason confused two-pole TS connectors with banana jumpers. Yes, I'm only interrupting the hot, and it is a normal Sensor patch bay like the image you posted.