Source four pars, NSI 4600+, HEADACHE!!!

[tenor_singer]

I just closed Oklahoma tonight and something weird was happening during the show that gave me fits.

I rented some source four par lights with 575 W bulbs (at least that is what the company claimed that they had in them... I'm still convinced that they had 750 W bulbs... anyhow... during the first scene the two pars that were plugged into channel one of my board kept raising and dimming, raising and dimming, raising and dimming......

This kept up until I had the light person hold the bump button until I could figure out what was going wrong. At the next blackout I quickly reprogramed our board's "full lights" memory to get rid of that channel so we could ease up on the bump button.

My question...

What causes that? I just had the NSI 4600+ dimmer pack fixed the week before (the fuse holder cracked and we replaced it with a new one.

[ship]

My guess:

loose connector or lamp contact, bad dimmer channels or their own contact points?

Some form of high resistance problem I would think.

Not saying that I'm very much useful in troubleshooting systems any longer beyond the fixture.

If it's a "last takes prescidence" type of problem with the control signal, perhaps it's a problem in the line communicating with the dimmers otherwise.

So many things to problem solve on the why part, it's much a question of where to start. Hopefully the start in checking what's easy first in a process of elimination from light board to lamp will be useful.

[Mayhem]

Start by swapping the S4's with other fixtures that are running correctly and see if the problem continues either with Ch 1 on your dimmer or the two S4's

If the S4's continue to exhibit the fault that you describe, report it to the hire company and tell them that you would like a credit for future hires, as you were unable to use their equipment due to a fault (make sure you are 100% sure that it is the S4's)

If the problem occurs with another fixture on Ch 1 then you know that the fault is somewhere within your equipment.

If you are able to, plug the fixtures directly into the dimmer, as this will tell you if the problem is present at the output of the dimmer, or in the cable between the dimmer and the socket into which you plugged the fixtures.

I am not familiar with the dimmer that you have but I wonder if it has a self-test option that allows you to bring up single channels, thus bypassing the control board. This will therefore isolate the dimmer. If the problem still exists, then it is somewhere between the dimmer and the board. Try swapping DMX leads and if that doesn’t isolate your problem, you will need to look at the board.

Also remember to look for physical signs of failure, such as discoloured or melted plugs/sockets, damaged cable, tarnished pins/sockets and any other signs of wear and tare. The fact that you mentioned having to replace a fuse holder makes me suspicious that there is something within your current set up that requires some attention. Although, fuse holders themselves can simply become tarnished and fail. Especially if the wrong fuses are used! Was the failed fuse holder on Ch 1?

Although I doubt that this is the cause of the fault, I am wondering if your DMX run is terminated?

Hope that this is helpful.

[tenor_singer]

The NSI 4600+ is a satellite dimmer pack rated for 1.2kW per channel. It has optional DMX or "something beginning with 'M and ending in - plex. I have the second as DMX was an option and more expensive (and we didn't have the funds yet).

Both responses have backed what I was thinking because when I plugged each fixture into a line that I wired a 15-Amp rheostat plug into as a "special dimmer" when I don't have the board space (only 16 channels) they didn't flicker.

I DID have the dimmer pack recently serviced and I am really not sure if it is the problem. The 3rd and 4th channel failed the night before. The fuses blew (which is why I am wondering if the company was wrong about the 575W bulbs even though the metal finned base had 750 stamped on it... they swore that even though it said 750, they put 575W bulbs in them as requested). Actually the fuses not only blew, but they were melted into the new fuse holders (the NSI series uses a 20-Amp ceremic fuse for safety) and I couldn't back them out. Maybe I am wrong, but a 20-A fuse and its housing shouldn't MELT because you are pulling 1140-W at 125V through it. I even checked to be sure that the pack was in a place where air could circulate through the heat sinks.

I'm sending the pack in for servicing, just to be on the safe side. I would never forgive myself if one of my kids got hurt because I didn't error on the side of caution.

Thanks for the input...

Tenor.

[cutlunch]

A quick look at the manual for these packs mentioned possible causes for these faults. As has been suggested they suggest checking the pre-heat setting. They also mention the length of control cable and suggest taking the console closer to the packs, using a shorter cable, to see if this is the problem. They also suggest if you are powering the console from the pack then you get a separate power supply for the console instead.

Some ideas from me is:
Do you you always use the same control cable or is the nearest one at hand at the time used. I would check the quality of the cable and joints.

Also is your control cable fixed in place or just a free run? Has it been layed near or across power cables.


When they changed the fuse holder they should have given the pack a thorough check maybe they didn't. Have you tried swapping the addresses on the packs to see if it is a control problem. If another pack has the same problem on that channel then it's a control problem.

[Mayhem]

Based on what you have said (sorry but I have not had a chance (nor the time) to check out the manual for these) each channel should only have a 10A fuse in them if they are 1.2K (1200W = 120V*10A)

20A would be the combined rating for the overall pack.

If the individual channel fuses have been fitted with 20A fuses then I think that would be the reason for the fuse not blowing and allowing the fuse holder and wire to melt.

Obviously, I am not familiar with this dimmer, so I would not take my word as being gospel. However, I would strongly recommend looking into this.

Especially as you suspect that the S4's were fitted with 750W lamps, which would give you 1500W, which would be more that the channel is rated for.

Sorry that I couldn't be more helpful but I am just a little pressed for time at the moment. Although, I hope that this at least provides some assistance.

[tenor_singer]

Originally Posted by Mayhem

Based on what you have said (sorry but I have not had a chance (nor the time) to check out the manual for these) each channel should only have a 10A fuse in them if they are 1.2K (1200W = 120V*10A)

20A would be the combined rating for the overall pack.

If the individual channel fuses have been fitted with 20A fuses then I think that would be the reason for the fuse not blowing and allowing the fuse holder and wire to melt.

Obviously, I am not familiar with this dimmer, so I would not take my word as being gospel. However, I would strongly recommend looking into this.

Especially as you suspect that the S4's were fitted with 750W lamps, which would give you 1500W, which would be more that the channel is rated for.

Sorry that I couldn't be more helpful but I am just a little pressed for time at the moment. Although, I hope that this at least provides some assistance.

I misspoke... they are 10-A fuses. I had 20-A fuses on my mind when I typed the last entry because I was thinking about the breaker pannel that each lead is plugged into. I've been busy trying to convert everything from what the previous director used ( over the counter 14-gauge, 15-A end extension cords) to a more safe 12- gauge SO with 20-A ends.

Sorry about that.

Tenor.

[Mayhem]

Too bad - as that would have solved your problem.

Just out of curiosity, are the 12AWG SO extension leads store bought, or made in house? My only other though links back to my original post about the leads between the fixtures and the dimmer and between the dimmer and the board.

Other than that, I don't think that I have much more to offer than what has already been said.

Please let us know when you find the fault as it would be interesting to hear what it was.

[tenor_singer]

Originally Posted by Mayhem

Too bad - as that would have solved your problem.

Just out of curiosity, are the 12AWG SO extension leads store bought, or made in house? My only other though links back to my original post about the leads between the fixtures and the dimmer and between the dimmer and the board.

Other than that, I don't think that I have much more to offer than what has already been said.

Please let us know when you find the fault as it would be interesting to hear what it was.

The SO extension leads were built by me. One of my students grandparents owns a large electrical retail outlet in my area called NEO Electric. They give me good prices on SO... usually below $0.60 per foot. I then bought commercial grade 20-A "T"-edison ends and made 50' and 100' leads.

I will be taking the pack down tonight to see what was wrong (I spent yesterday after school driving for four hours to return the source fours to the rental company). They are troubleshooting their lights at their end and will let me know later today. They are really great guys and knocked off the two week spot rental fee as compensation for all of my troubles... even knowing that it possibly wasn't their fixtures.

Thanks for the help and I'll post more information as I get it.

Tenor.

[ship]

$0.60 per foot is a ok price and decent in many places but it’s more retail than a huge discount. Sorry but Grandpa bless his hart for helping should have shopped around more. Given he does not buy or stock the stuff much, it’s a fair price. On the other hand for Edison plugs, I hope you did save lots of money there. (As a rule when posting in public, retail price is all you should list and defiantly not sub-retail deals or actual cost.) In your case, the $0.60 per foot is a decent bench mark to shoot for or get lower than for others. While I have not priced it out recently, I find as of about last year retail prices for 12/3 SO ranging from $0.46 per foot to stopping tracking it when it gets above $0.65 per foot given these retail prices are at least a year old and probably higher by now.

Out of curiosity, why did you go with 5-20 NEMA Plugs? This also assuming you went with commercial/industrial grade plugs as required such as the Leviton #5266C plug? My old theater went with them given I trained the tech people using the gear and it thus limited things plugged into the equipment to 20 amp outlets, and we could not afford total stage pin upgrading. On the other hand, the last time I made a Edison to three phase thirty amp twist L21-30R adaptor, I used the 5-20, 20 amp plugs on it as required by code in adapting from one amperage rating to another by way of only jumping one amperage rating to another - given such an adaptor is against code to do but was necessary in at least complying with some of the NEC. The +20 year veteran stage hand on site than took the adaptor, looked at the plugs on it, scratched his head not once than twice, perhaps asked the crew chief that also will have scratched his head about the parallel blade plug with it’s neutral now perpendicular to the hot. That professional stage hand than wasted no doubt a hour or three in re-plugging these against code adaptors that were at least using the proper plugs to a 15amp Parallel U-Ground Edison 5-15P NEMA plug. For the show, they then were plugged into a AC Distro rack that was using NEMA 5-20 convience outlets which would tend to fit both the 5-15 and the 5-20 plug. That professional stage hand just never thought about the T-shape to the 20 amp outlet as opposed to that of a 15 amp outlet, thus never suspected that the 20 amp Edison plug I gave him would work, and more than that no doubt had some choice words for my abilities in screwing their show. Egg on them not me still meant lots of wasted time given a not much used plug that confuses people.

Of note also would be voltage drop. That 100' cable while standard to load it to have 20 amps, really would not be rated for that much current given 12/3 cable doing the work. 12/3 cable in 100' lengths might more reasonably be down rated for less amperage than your 20 amp plug will allow for. More than this, while there is a specific amperage rating of the 15 amp plug, it’s overall design is exactly similar to that of the 20 amp plug. The only reason for it’s T-Shape is in preventing design loads of over 15 amps from being plugged into a 15amp rated system. That’s a good thing but assumes home owners using the cable. Strike that, stage hands often will also not know any better given the above.

Statement here is yes, for a 20 amp load, you have installed a code compliant plug on the cable to carry the load - even for stage use where it’s recommended for twist or stage pin but as yet not required. But in making this cable, you have just confused one heck of a lot of people that just might behind your back change plugs anyway in making this safety factor you installed in the cable useless. While I do see the 5-20 plug as useful especially if in a mixed inventory of 12/3 verses 14/3 cable, the 5-20 plugs might cause maintenance problems. Me and you in knowing better and using the cable to limit what it gets plugged into is a good reason for it’s use. Unfortunately in being Edison, others will just swap your plugs behind your back and even as added insult while doing so apply an improper strain relief (read the instructions?), and lose parts in at best returning “field stripped” plugs totally disassembled that loose parts - if not just throwing them out and calling you names. At some point, that value of changing to stage pin or twist for 20 amp loading will pay off in at least labor in keeping this 20 amp Edison system running.

Sorry and I agree with using a 20 amp Edison plug, it’s just the other 90% of the industry that don’t know better but don’t that will totally screw up your system.