# Why won't it light? Troubleshooting conventionals



## derekleffew (May 20, 2011)

Inspired by: 

NevilleLighting said:


> ...The next thing I want to develop is an exercise where they learn how to troubleshoot....I do try to cover it some by teaching them that the least likely reason for a light to not light up is a blown lamp. At the very least check all other possibilities before you grab a new HPL.



And one of my test questions:

> _____ If a fixture does not light up when the board operator calls it up, what’s the FIRST thing to check?
> A. Lamp; B. Dimmer; C. Multi-Cable; D. DMX Cable


It appears [USER]NevilleLighting[/USER] and I already have differing opinions. 

Somewhere on here we once had a discussion regarding "Do you check (X) The most-likely possibility, or (Y) The easiest-to-check possibility; when trouble-shooting?" but I can't find that thread, so let's start over.

(Z) Maybe a list of all the reasons why a light might not light, and then after a week we'll prioritize them?

And since it's been a while, let's make this a OotD--students only for one week, please.


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## CrazyTechie (May 20, 2011)

I would say the lamp is the first to be checked as it is the easiest to access in most cases and from there I check to make sure the circuit works by plugging in a known working light and trying the channel again. If that does not work I go check the dimmer racks for a flipped breaker and to make sure there is a signal to the dimmer, but if it does work I proceed to check the cabling between the circuit and the instrument.

In list form:
-Check lamp
-Check circuit with a working instrument
-If that does not work go check the dimmer racks for a signal/flipped breaker
-If the circuit works check the cabling from the circuit to the light


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## DuckJordan (May 20, 2011)

Your test question should have another option. Check the patch!

The order I always go in is whichever is easiest. It generally turns out like this.

Patch
DMX
Lamp
Extension
Circuit
Dimmer

In that order. I've almost always found it to be an extension in our space.


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## CrazyTechie (May 20, 2011)

DuckJordan said:


> Your test question should have another option. Check the patch!



Ah! I forgot the patch, and if I recall correctly the last show I did ME for I had switched a light when I patched it into the board so It's definitely something that should be checked.

EDIT: While troubleshooting why a light wasn't turning on and after finding out that the breaker on the dimmer kept tripping after I would turn it back on, I went to check the extension cords and I found this upon opening one of the ends up and quickly determined why the breaker kept tripping:


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## NevilleLighting (May 20, 2011)

[Mod note: This post had previously been hidden, and is being revealed now (05/26/11), one week after the original question was asked.]

Derek, I think you make a good point there. Part of the check also depends on where you are in the process. Early in the process my first reaction is to check patch. Second, I check to see if juice is getting to the fixture. Third I give it a continuity check. Fourth I go after the lamp. If the lamp passes a visual inspection I may open the plug, or at least tug on the wires. I also give the socket a good inspection. In one theatre I have a lot of 360Q's and lamp seating fails five times more than the lamp. I see students reach for that HX600 way too early in the process. It's an expensive rush to judgment. All too often I hear "light doesn't work. someone get me a lamp". 

I can see an easy point in going for the continuity check first, especially if the show is running and all of the changes and gremlins have been worked out.


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## CrazyTechie (May 20, 2011)

I'm not sure what you mean by making sure that juice is getting to the fixture but if I had to guess it would be making sure that a load is capable of traveling to the fixture. The only problem with a continuity check is that it doesn't tell you if the cable or whatever you are checking will actually take a load. I had an extension cord that passed a continuity check but it did not take a load, the reason was that the wires for the hot were just barely touching the pin so that a signal could be sent but not enough for power to go down the line.

As long as you are doing both checks on the cable everything, in my opinion, will work out as far as cables are concerned. However, if you just do continuity checks on the cables then you are setting yourself up for a cable that wont take a load in the middle of your rig that you have to switch out when you do a channel check.


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## derekleffew (May 20, 2011)

CrazyTechie said:


> ...I went to check the extension cords and I found this upon opening one of the ends up and quickly determined why the breaker kept tripping:



So you're saying those letters N, G, H (inside a Union Connector plug) or words WHITE, GREEN (inside a Bates connector) actually mean something? I thought electricians didn't need to know how to read, just tell colors. 

Black to Brass, White to Silver, Green to Green.


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## techieman33 (May 20, 2011)

derekleffew said:


> So you're saying those letters N, G, H (inside a Union Connector plug) or words WHITE, GREEN (inside a Bates connector) actually mean something? I thought electricians didn't need to know how to read, just tell colors.
> 
> Black to Brass, White to Silver, Green to Green.


 
I don't remember ever seeing brass, silver, and green screws on a stage pin connector, and I think I've had most if not all of the major manufacturers connectors at one point or another.


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## CrazyTechie (May 20, 2011)

derekleffew said:


> So you're saying those letters N, G, H (inside a Union Connector plug) or words WHITE, GREEN (inside a Bates connector) actually mean something? I thought electricians didn't need to know how to read, just tell colors.
> 
> Black to Brass, White to Silver, Green to Green.



I thought so too but apparently electricians need to learn how to read as well. Although we could try to teach a "color-by-number" system and number them but we'd have to remember how to count as well.


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## JChenault (May 20, 2011)

Derek

I think there are actually be two questions here.
1 - during dimmer check, a lamp did not come up. What do you do to troubleshoot.
2 - You have hung a circuited the show and a lamp does not come up. What do you do to troubleshoot.

Two very different scenarios with ( at least for me ) very different troubleshooting paths.

( Ignoring touring and rep houses which make things too complex for this thread. )


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## ruinexplorer (May 20, 2011)

DuckJordan said:


> Your test question should have another option. Check the patch!
> 
> The order I always go in is whichever is easiest. It generally turns out like this.
> 
> ...


 
If you almost always find that it is a problem with the extension (air gap?), why is that not your first check? Just for point of discussion.


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## DuckJordan (May 20, 2011)

ruinexplorer said:


> If you almost always find that it is a problem with the extension (air gap?), why is that not your first check? Just for point of discussion.


 
Because while it may happen to be the extension at most times at this venue it does not necessarily happen at another. Its also good to point out that right before i came they had a lighting professor retire (he was good at designs not so good at equipment upkeep) and most of the extensions were created during his time here. So as those bad cables are found and fixed the problem is slowly starting to become less common.

Its also good to follow a routine as it helps create a familiarity in how to troubleshoot. No steps skipped means no steps forgotten.


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## FlashBang (May 20, 2011)

When hanging lights I always have a long extension of Edison/T3 plugged into a house circuit. Its easier/quicker to grab the extension and plug in a light then to actually remove and replace a lamp when troubleshooting (and if its focused, you won't disturb that).

Given that, my list would go:
Patch
Lamp (plug into known working circuit)
Circuit (test by plugging known working fixture)
Extension (if not plugged direct)
Dimmer


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## mstaylor (May 21, 2011)

May I suggest to think about PARs as well as lekos and fresnels. There may be differences or additions between the two. I will only say I wouldn't follow any list I have seen so far.


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## DuckJordan (May 21, 2011)

mstaylor said:


> May I suggest to think about PARs as well as lekos and fresnels. There may be differences or additions between the two. I will only say I wouldn't follow any list I have seen so far.


 
This got me thinking, and its something that also commonly happened.

Patch
DMX
Shutters/Iris
Lamp
Extension
Circuit
Dimmer


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## NickVon (May 22, 2011)

Ahh the classic, Shutters never got pulled failure.  

I think JChen, hit it on the head. Depending on the circumstances i think the process changes.

during a "hang" i'd first check the Shutters and Patch.

If something has failed during dimmer check i think i'd start at breakers then proceed to go up to the instrument and check a lamp failure. then extensions.

I do asribe to the check the easiest to get to failure points first (especially in my venue where it's a Genie lift to get to the grid.


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## mstaylor (May 22, 2011)

I am an arena guy and getting to the grid means either a rigger or a 60ft lift. It changes my thought process.


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## chausman (May 24, 2011)

WAIT!!! Are you all saying there should be some sort of systematic checking method that we use for all of out fixtures? 

I would just check what is easiest. If I'm using the RFU, I would probably check that I brought up the correct channel and then that it is plugged in correctly and where I want it to. Then, a lamp would be my next check, since I can check that without leaving the fixture. Then start checking cables and breakers. (by swapping with known-working cables and fixtures nearby)


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## derekleffew (May 24, 2011)

Does the methodology change depending on what tools one has on one's person? 

What tools might one find beneficial?


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## chausman (May 24, 2011)

derekleffew said:


> Does the methodology change depending on what tools one has on one's person?
> 
> What tools might one find beneficial?


 
RFU. (and now to get up to 10 characters)


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## dramatech (May 24, 2011)

Just an aside to the thread.
I purchased two Source four instruments off of ebay, that were almost brand new. I paid next to nothing for them, because they were listed as not working and only good for parts. The problem was the wiring of the stage pin connector, the same as the one shown by crazytechie. The hot lead was connected to ground. Both of the instruments had the power cables cut off at the halfway point, but included in the shipment.

Not being a student, I can't respond to the Questions from Derek, but a clue to the tools that can help troubleshoot: some start with the letters 1)"G" 2)"U" 3)"V" 4)"M". I'm sure that there are many others, but can you name the four that I have indicated?

Tom Johnson


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## seansbar (May 24, 2011)

I know the "G" bring it with me at every call. I've even had the wife sew a holder with a belt loop for me.


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## LXPlot (May 24, 2011)

My order would be:

1)Check that I brought up the correct channel
2)Check to see if the channel is correct in patch
3)Check to see if the breaker on the dimmer might need to be reset
4)Check Lamp
5)Check dimmer--see if another unit works in same area
6)Check pigtail, internal wiring of unit, etc.

Obviously, if multiple units are not responding, I would react differently


dramatech said:


> Not being a student, I can't respond to the Questions from Derek, but a clue to the tools that can help troubleshoot: some start with the letters 1)"G" 2)"U" 3)"V" 4)"M". I'm sure that there are many others, but can you name the four that I have indicated?


 
1) Grenade-Socapex. Lamp tester, real handy and real quick. I should find myself one.

2) Utility Knife. Used for a variety of things, fixing pigtales/plugs, cutting gafftape, etc.

3)Voltmeter is the best I can think of...although I don't know why you would need a multimeter and this.

4)Multimeter. Duh. Doubles as a lamp tester or continuity tester, also could be used for cable testing.

If 3 is voltmeter, than 4 is maglite.

How'd I do?


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## cdcarter (May 24, 2011)

dramatech said:


> Just an aside to the thread.
> I purchased two Source four instruments off of ebay, that were almost brand new. I paid next to nothing for them, because they were listed as not working and only good for parts. The problem was the wiring of the stage pin connector, the same as the one shown by crazytechie. The hot lead was connected to ground. Both of the instruments had the power cables cut off at the halfway point, but included in the shipment.
> 
> Not being a student, I can't respond to the Questions from Derek, but a clue to the tools that can help troubleshoot: some start with the letters 1)"G" 2)"U" 3)"V" 4)"M". I'm sure that there are many others, but can you name the four that I have indicated?
> ...



Unsure on U + V, but G sounds a lot like GAMChek, and I'd put money on M being multimeter or mag.


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## dramatech (May 24, 2011)

cdcarter said:


> Unsure on U + V, but G sounds a lot like GAMChek, and I'd put money on M being multimeter or mag.



You are correct on both G and M. The privious post was correct on V as Voltmeter. I realize that Voltmeter and Multimeter are a bit redundant, but I was just covering that fact that some people call it a Voltmeter and some a Multimeter. While a Voltmeter is just a portion of a Multimeter, we don't always call items by their exact and correct names. As for the U, I was thinking mostly of electronic testing gear, altough all of the tools mentioned for each letter are pretty good items to have. U is a fairly recent tool specifically design and sold for theatre electricians.
I didn't mean to hijack Derek's question of the day thead, so let's get back to the troubleshooting methods, and order thereof.

Tom Johnson


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## cdcarter (May 24, 2011)

dramatech said:


> You are correct on both G and M. The privious post was correct on V as Voltmeter. I realize that Voltmeter and Multimeter are a bit redundant, but I was just covering that fact that some people call it a Voltmeter and some a Multimeter. While a Voltmeter is just a portion of a Multimeter, we don't always call items by their exact and correct names. As for the U, I was thinking mostly of electronic testing gear, altough all of the tools mentioned for each letter are pretty good items to have. U is a fairly recent tool specifically design and sold for theatre electricians.
> I didn't mean to hijack Derek's question of the day thead, so let's get back to the troubleshooting methods, and order thereof.
> 
> Tom Johnson


 
Of course! Ultimate focus tool!


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## derekleffew (May 25, 2011)

cdcarter said:


> Of course! Ultimate focus tool!


I never would have gotten that one, and I use mine all the time, as a convenient continuity checker. I was thinking something about unity, which I know, doesn't make any sense.


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## dramatech (May 25, 2011)

cdcarter said:


> Of course! Ultimate focus tool!



You are absolutely correct. I love mine, and thought it was just about the greatest, right up until I got my Ultimate flat focus tool. As I have gone through some of the previous threads on focus tools, I realize that I own them all. (You can do that when you are retired, and your hobby is being a theatre tech). I really love both of the Ultimate focus tools, but the flat tool sits in my back pocket so well, that I forget it is there, and have only discovered it's presence as I undress for bed.

Tom Johnson


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## mstaylor (May 25, 2011)

+1 on the Flat Focus Tool. I have gotten to the hotel many times to find it in my back pocket.


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## LXPlot (May 25, 2011)

cdcarter said:


> Of course! Ultimate focus tool!


 
Oh! I should've got that!...although I guess I kind of covered continuity tester with the grenade...


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## techieman33 (May 25, 2011)

Yeah I was confused too, I thought it was 4 different tools for different things, not all for checking power.


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## itie (May 25, 2011)

I worked on a movie set once and I spent the day talking to the board opp. He told me that you should check everything on the ground before sending someone up to the fixture. I'm guessing because it cost more time and money to stop and get a guy on the ladder, but it makes sense at least for my school. 90% of the time there is only one or two technicians that can troubleshoot the problem and they are always in the booth. so we usually start with the board then the dimmers since we have to pass them to get to the cat walk. 

Thank You
Giovanni


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## echnaret (May 26, 2011)

I always checked dimmers last at my college, because they were in the building's mechanical room. The key was in the booth, and the entrance was halfway around the building. You could exit the room near the theatre, but because you needed to check the carbon monoxide detectors before going in, there was only one way you could enter.

In general, I agree that the order is really determined by what is most convenient (and whether the light has previously worked since it was hung).


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## derekleffew (May 26, 2011)

derekleffew said:


> ...(Z) Maybe a list of *all* the reasons why a light might not light, ...


That part was a trick question. There is actually only one reason* why an incandescent lamp won't light:
*Power is not being conducted through the filament!*

This can then be further sub-divided:


 Power is not getting TO (and from) the filament. (Many reasons why this might be. Most [but not all] of which have been stated.)
 The filament is broken (non-continuous).
 
*Let's ignore for this discussion:

It's an ERS and the shutter s are closed (or a Fresnel with closed barn door s); thus the lamp is working, but we can't tell without being at the fixture.
It's a well-used archaic lamp, and the tungsten that has deposited on the inside of the envelope has darkened so much that no visible light is being emitted.
-----
It's been a week, so the discussion/question(s) is/are now open to everyone.


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## mstaylor (May 27, 2011)

First, I prefer not to touch the light if it is focused. Usually I work with temp systems, concerts or touring theatre rigs. The first thing I do is check the breaker, then hit the test circuit. If it doesn't work then I have eliminated the board and the DMX between the board and dimmers. If it does work, check the patch. Since you are at the dimmers, switch socos to see if the soco in the dimmers works. At the truss, it depends if the lights are hardwired or powered from breakouts or permanant outlets. I switch plugs to see if the light works or test for power. If I have power, then check the plug. My last thing is to change lamps. This is simply to avoid screwing with the focus. If it doesn't matter, if I have power I go to the lamp then the plug. If it is a PAR, the first thing I do when I get the light is check the bottle, then the sugar cube.


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## derekleffew (May 27, 2011)

mstaylor said:


> ...If it is a PAR, the first thing I do when I get [to] the light is check the bottle, then the *sugar cube*.


Is this common jargon? Has anyone else ever called it (or heard it called) a sugar cube?


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## Nelson (May 27, 2011)

I would say that my approach to this problem would depend on the venue.

When a light fails in our auditorium, I check the lamp first. We've never had a dimmer problem or even tripped a breaker. Wiring is all in good shape as well. The fixtures are also in good shape, so a fixture wiring problem is unlikely. Therefore, I would check whatever seems to be the biggest problem. If you have flaky dimmers, for instance, I'd check them first.

My approach also changes depending on the symptoms. If none of the fixtures light, there's probably something else wrong rather than 50 broken filaments! Or if I have three fixtures on one dimmer and they all quit working at once, I might check the breaker, dimmer, wiring (like two-fers), and control equipment (in that order). 

Of course, the very first thing I check is if I turned on the right circuit or brought up the correct cue.


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## mstaylor (May 28, 2011)

derekleffew said:


> Is this common jargon? Has anyone else ever called it (or heard it called) a sugar cube?


That is what they call the little block, at least in my area, that has replaced the wire crimps. Also bottle is the porcelain. I find about a 60/40 split between the two, when it isn't the lamp. The other day I had three out, all on seperate socos, it was all soco pin problems.


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