All, thanks for the great info. I'm already a
bit over budget this year (
mackie crapped out so had to buy a new sound board) so this is on top of that. I'm hoping to get a go ahead tomorrow and will start following some leads. Any more comments on using them (or how useful they are) still appreciated.
In use of them, open up and inspect the tension and gapping of all plugs on or all cable feeding them. For some reason if using the more or less standard 60A
stage pin plug to feed such a
fixture, they constantly are getting loose set screws at the
plug. Once a year all such plugs need re-torquing even if in theory against code to do, it's necessary. Due to the load, the conductors feeding the plugs expand some under the set screws and re-settle after expansion thus you now have loose plugs. This especially if using "Union" brand plugs, but common to all. Check the tension on all
wire to screw terminals - they loose you now will most likely will have a melt down at the
plug. (I have lots of examples of this condition on my wall of shame - the plugs will even melt together.) Not just a question of if you didn't
wire the cable, it's not to your specs, even if you wired the cable it might after heating up not be to your specs. Where possible, open up all cables and plugs and test the torque of the set screws. Normal electrical practice does not allow or recommend that you re-tighten stuff such as
circuit breakers... don't care, in this case it's I believe 20 inch pounds of torque that's required, verify it if you have time and or at least do a sampling of what you have or get before using it. If what you test complies, fine, if what you have does not, be cautious - might not be you that wired the stuff, but it is you responsible for making it work in the end.
No matter if rented (be cautious) repaired, or new, if in your
system, do at least a spot check of a few cables and plugs (remember that the 60A is reverse
neutral/
ground from the 20A version), any even if you built it could have torque problems due to the amperage. I did such a policy of once a year checking all the plugs, it worked well in reducing repairs by about 90%.
After this on a 5Kw
fixture, extract the lamp. If
Strand Bambino
fixture, that's easy, if Mole Richardson, caustious of the
base often broken
porcelain but still fairly easy to remove unless welded to the contacts. If most others, be very careful in extracting the lamp from it's
base. Often a lamp will be hard to remove, than come loose all at once in the upper pinch hitting the top of the
fixture. Hit the top of the
fixture in extracting the lamp and you now have very expensive trash in your hands. Still very necessary espeically in rental equipment if not your own to verify that the lamp, it's
base and it's wireing is in good condition. Cement holding quartz glass to
porcelain in good condition or all cracked and leaking silica sand? Fine to some extent as long as gravity mounted but if it's loose in the
porcelain part of the lamp attached to the pins, much less if hung in other than vertical
base down with silica sand leaking, replace the lamp. Such lamps often have issues with heat - at times they will have a hose ring attached around the body of the lamp to help keep it together - that's fine as long as the lamp is in good shape.
First examine the lamp. In good shape? Fialment still hanging off it's
filament hangers, no white finger print spots to it
etc? Look at the pins... some oily coating is fine as long as there was no pitting and or welding to the lamp
base. Welding of the lamp to it's
base is a bad thing and induced
filament failure lamp failing during a show heat to the - you need this lamp to work theory. Look at the
filament again, bunch of sparkley cracks, thinning out of the
filament towards the center or anything unusual? Clean the lamp just to be sure if fine. If it's pins were fine also, it says good things about the lamp
base.
Now with lamp removed, pull out an inspection mirror and flash light. Have a look at the lamp
base contacts with it and verify that it's not all pitted, oxidized and or welded in being shot. Your lamp upon removal should have had either something that releases the tension either a lever or
wing screw, or tension itself by way of rocking you are able to get the lamp out. IF that lamp came out too easily, you have shot retention springs on the lamp
base and will no doubt have also seen some welding going on given the
current.
Look at the
porcelain of the lamp
base - this especially if Mole Richardson in brand, verify that it's not cracked. OF cracking, also verify that your
lens has a
safety screen on it - not safe to use without one.
Reflector clean and the adjustment focus knob works plus stays in place. Make sure that the
reflector is also tight.
Following this, get that inspection mirror and flash light in behind the
reflector. Have a look at the condition of the wiring especially as it leaves the lamp
base. If one say sees
insulation flaking off the conductors, it could short itself should it be put into spot position - don't use such a
fixture that has
insulation flaking off. If you can on a few, flex that heat
wire inside the
fixture that runs between lamp
base and
switch or
strain relief and see if it cracks. Also a sign of a bad
fixture. If accessable, the
fitting that converts heat
wire to the
fixture cable is also suspect in having loose terminals.
Lots to check in a 5Kw and anything over 1Kw
Fresnel. Spot checking at very least is a good thing. Heat is your enemy due to expansion and contraction and materials just getting hot enough to break or become brittle.