View Full Version : Desisti "Rembrandt" 12K HMI
Bob Hart May 12th, 2011, 05:26 AM Those who remember history back might recall one of my less wise adventures, this HMI light which I did not understand at the time ( small matter of 12K versus 1.2K ). Whatever, I have the lamp.
After a good long time, I have finally started on it, going through looking for wear/tear and trouble. The Hobbs meter has 11,000 hours up on it. The reflector has some impact marks on it but it is otherwise good, so somewhere along the line, sombody has been suddenly amazed by something violent.
There are no longer any manuals or handbooks that I can find on the web. Older lamps like this have been built before computer records and .pdf files became part of the archiving process.
I have run into a little puzzle. There were things rolling and rattling as I moved the lamphouse but nothing loose inside. I found in the junction box on the side, a large wingnut and a thrust bearing. It looks like they have been there a long time. Luckily it seems nothing electrical has been touched by these loose metal pieces.
The wingnut does not seem to be missing from anywhere. It is not a fastener for the pigtails on the globe, It is a different size.
The thrust bearing? Goodness knows where that is from? The lamp carriage flood/spot movement appears to be intact and there is not any excessive play in the mechanism except for the cable itself which is adjustable.
If anyone has any exploded diagrams of this lamp or images of its entrails, any info would be appreciated. Details on the placard are :-
Desisti "Rembrandt" mod.2450
S.N. 0191.
Regards all.
Chris Ficek May 12th, 2011, 08:13 AM I have a point of contact with the president of DeSisti North America and I will forward your info off to him. He seems like a very decent fellow and I'm sure he can direct you better than anyone. You've actually just reminded me that I owe the community an update on my negative posting about DeSisti at The Colour of Light - Home (http://www.thecolouroflight.com) based on this gentleman's professional response...my bad.
Bob Hart May 12th, 2011, 10:01 AM Chris.
Thanks very much for your endeavours on my behalf. It is much appreciated.
I initially was not too impressed with the metal work of the case. I thought it was like something I could bend up with a pair of tin snips except for the pressed vent slots. However I found a channel frame underneath, a much stronger build method, resistant to knocks and bumps.
The deeper I mine in, the better I feel about exloring. There are a few things that need just that little tidy up like insecticide residues. Who ever did the spider kill in the US when the light was shipped didn't muck around or maybe it got another one out here too. I saw a bit of residue when it first arrived which I wiped out.
Having pulled it apart some more, I have found white dried fluid runs, some corrosion and a dead bitey in the junction box.
I also found the shields inside the top have sharp deep dents in them, possible evidence of a globe explosion along with the dents in the reflector,
Bob Grant May 14th, 2011, 07:09 AM Pictures please, a video of the first lamp startup would be good.
Hint from the now much wiser, do not look at the lamp as it starts up just to see what happens, I got the worst migraine of my life doing that with a 150W HMI lamp.
Bob Hart May 14th, 2011, 09:46 PM Bob.
I should have thought of a before and after sequence, however will video the event.
As for getting a flash, one of my jack-of-all-trades semi-skills is stick welding, so the reflex for avoiding eye injury is well established. Having seen the depth of those sharp dents from flying glass inside, the fresnel door will definitely be shut.
Bob Hart November 24th, 2012, 08:58 AM After a long hiatus, I finally got some power into this thing and it lives, searingly bright. The moths have no hope.
Bob Hart November 25th, 2012, 06:40 AM Here y'go Bob.
Here's a happysnap of the 1.2K that wasn't.
Bob Hart December 22nd, 2012, 07:20 AM Well here it is, doing what it is intended to do, images from a short conceptual test for an upcoming project.
The operator in front of the lamp is not me but Steve Rice, (Darling Films) who came along to assist.
Camera. SI2K. Lens. Nikon 85mm f1.4 at f1.8. motion image for end titles at close of teaser clip.
Brian Drysdale December 23rd, 2012, 06:03 AM How are you powering the 12K? Any time we've used them it has always involved hiring a generator?
Bob Hart December 23rd, 2012, 10:37 PM Initially the scheme was to test the light on an industry lighting generator however the owner-operator wanted a guarantee for repair of his generator if the light blew it up. At Australian labour costs and given that his truck would have to be pulled apart, repairs and claims for lost work. On the math it could have been easily $8,000 at the kickoff and rising.
It was decided to buy in a $6,300 ( + customs, GST) 20K single phase generator from a US based vendor which ships worldwide. If the light did not perform satisfactorily, the generator could be onsold locally at little or no loss. It is bit more noisy than a double-blimped truck generator but some of the noise is from the panel trailer it is sitting on.
GENERATOR SYNCED TO CAMERA. 25P 50Hz - YouTube
Brian Drysdale December 24th, 2012, 09:54 AM Sounds like a bit of an investment just to test a light. I guess the possibility of selling the generator on off sets the risks,
Bob Hart December 24th, 2012, 10:05 PM That pretty much was the scheme. I was fairly confident that the ballast and the light would work after giving everything a clean, swabbing the insecticide residues out and metering everything that could be passively metered.
It is one of those situations where to get anything back you must put some more in. Some misgivings there but it's done. One of the proper lighting guys over here expressed interest in buying it if I wanted to sell after it was proven. I understand that most of the few other 12K - 18K HMI lights here have magnetic ballasts. After the current indie movie project is done and dusted, I may then onsell the whole package.
I think in fairness, I should mention a US based lighting tech by name of Gilbert Navarro whose outfit trades as Galaxy Lighting and Repair. He was very helpful despite the likelyhood of not making any profit from his advice to me. His website also has lots of useful information.
I hope Chris will afford me this one indulgence of mentioning a commercial entity who may not be a site sponsor.
Brian. Offtopic. If you were in the film industry on the mainland UK in the seventies-eighties, you might have run into Ricey who was then in set construction and worked on the the original Star Wars series, Hanover Street, Dark Crystal, the first Indiana Jones.
All the best for Christmas and the New Year to all and your own.
Bob Hart January 1st, 2013, 02:32 AM A bit of a way to spend a Friday night. Lighting test shot on SI2K.
When daddies go bad... - YouTube
Bob Grant January 5th, 2013, 04:15 AM Using a SI2K to test a 12K, that could lead to some confusion :)
That test does seem to show how useful such a light is. A big light source far away looks different to a smaller light source close up. Despite the seemingly huge number of lumens coming out of a 12K, outdoors they don't go that far.
Bob Hart January 5th, 2013, 07:17 AM The light was about 300 metres back up the valley. Gavan was not sure how it would go as the lamphead is smaller than 12K lamps he is accustomed to from his 35mm film TVC and Singapore/Jakarta days. He is content it will do what will be wanted for a teens in the bush in jeopardy project.
With the big stand and the power needed and just three bodies to move stuff around and do the shots, it is not a redhead to bung here and there on impulse. One needs to plan and scheme.
Bob Hart January 29th, 2013, 11:11 AM On the strength of the 12K lamp working with a near end-of-life globe in it, I ordered a new globe in. On arrival, this globe appears to have a liquid stain within the envelope. The old globe had lots of stain and melted bits within and spots of dust and rust burned into the outside of the envelope which is why I am not too keen to keep on using it.
Explosions seem to be fairly violent, judging from previous damage within the lamp housing, sharp-edged gouges in centre of dents inside the bodywork, on the reflector and some small chips out of the fresnel ridges inside.
Is a stain inside a new 12K double-ended globe normal? I imagine the chemistry which vaporises to affect the colour temp of the light has to reside somewhere.
Bob Hart October 30th, 2015, 11:07 AM Over winter, the lamp has been in storage. This year there has been a rat infestation which proved impossible to control by non-chemical means until an electric rat trap which actually worked was discovered. Poisons are not an option due to endangered wildlife being collaterally poisoned from eating the dead rats which stagger outside looking for water
Unfortunately the beasts managed to get inside the lamphouse and have eaten the woven heat-shield around heat resistant cabling and two inches entirely out of the small cable to the door switch.
Whilst I am about pulling the whole thing apart just to get at the damage, I am minded to replace the thick lampholder cable shield material as well. One piece was entirely missing on arrival when I first received the lamp, maybe a prior misadventure with rats in its former home, the US.
Replacement materials are proving hard to locate unless one wants to buy entire commercial sized reels of the materials offshore.
Any advice as to sourcing smaller quantities of woven heat resistant wiring sleeves and heat tolerant 18AWG cabling would be much appreciated. The original wiring in the lamphouse is old-style woven fabric insulation which was discontinued out here very many years ago.
Bob Hart October 31st, 2015, 03:12 AM THE 12K LAMP SAGA.
So here's the rub. The lamphouse was made by Desisti. It is put together around a metal frame. Internal panels are fixed with screws. Light-trap vents are fastened with screws. The outer skins are attached with rivets. Superficially it represents the way aeroplanes are put together.
I really don't like to take on things unless I do them properly. However, do I drill out 40 mongrel rivets, remove the skins, neutralise the rust in the contact faces like a good airframe engineer?
Next, refasten with new rivets, or just leave it and paint over it to entrap the oxide floaties, which may yet still escape to get on the quartz bulb and shorten its working life if the joints are disturbed in transport?
The lamphouse appears hand-built. Except for some generic components and louvre slots, it is something you could put together in your shed with a welder and tin-snips.
However, that said, the Italian manufacturers of the times and maybe still, had a passion for their engineering doings.
There are nice little touches like hand-threading all screwholes in the metal frame instead of using speed screws which cut their own threads with sometimes haphazard results.
Then there was their practice of through-bolting a sub-assembly to the frame by threading the holes in the sub-assembly and adding a locknut on the end of the bolt.
You won't see this thoroughness in Chinese knockoffs.
A final cautionary note. If you import a pre-used large appliance, there are requirements that it be treated for vermin and insects. There were residues inside the electronic ballast and the lamphouse. I think that the people may have used aprocarb as the taste began to ermerge in my mouth when I started cleaning, sanding and wiping out the rust in the lamphouse.
So take care humble peons. Wear gloves and long sleeves and a dust mask if doing up appliances sourced from offshore. Also, if anything electrical on a circuit board looks matte-finished and white, treat it with intense suspicion. Don't fracture it or cause it to make dust. Some older heatsink materials of the vintage of this lamp contain beryllium oxide which is a potent carcingen.
Chris Medico October 31st, 2015, 06:54 AM Any advice as to sourcing smaller quantities of woven heat resistant wiring sleeves and heat tolerant 18AWG cabling would be much appreciated. The original wiring in the lamphouse is old-style woven fabric insulation which was discontinued out here very many years ago.
Is something like this suitable?
http://www.amazon.com/High-temperature-wire-AWG-roll/dp/B001ALR83U/ref=sr_1_14?ie=UTF8&qid=1446296768&sr=8-14&keywords=high+temperature+wire
http://www.amazon.com/CS-Hyde-Temperature-Fiberglass-Silicone/dp/B000REGUBM/ref=pd_sim_60_5?ie=UTF8&dpID=41KZvZULaFL&dpSrc=sims&preST=_AC_UL160_SR129%2C160_&refRID=095SKRV016YCMENA8MMW
Bob Hart October 31st, 2015, 08:22 AM Chris.
Most excellent assistance. Thank you Sir.
Given I have the lamphouse stripped down to the bare skeleton except the two riveted side panels, I might as well do the job properly and eliminate as many possibilities of catastrophe as possible.
The main leads to the carriage look good. Only the sleeves themselves appear beaten. That fabric tape is also what I was looking for but could not find.
Lightmaker ballasts are apparently becoming harder to have fixed except back in the US, so the lamp needs to be the best it can be.
Needed for a small indie shoot in December - January near Jarrahdale, south of Perth.
This is the really good side of dvinfo at play again. Thanks Chris.
Bob Hart November 1st, 2015, 05:50 AM THE 12K LAMP SAGA - CONT'D
Sometimes negative happens-chance has its upside. Yes I am vexed about the rats shredding the wiring. It is a major-league p---off. However in the lowest innards of the beast I found three foreign objects which are not lamp parts.
One is a thrust bearing, another a brass wingnut which fits nothing, the last is a small 4mm x 40mm machined shaft. My guess is somebody used the top of the lamp as an emergency workbench and the small parts fell in through the top vent.
There were smokey signs that sometime, something went across via one or the other of these metal intruders. I have been intrigued by some outward-facing dents in the rear cover. The cause is now apparent.
Somebody in the past appears to have tried to stop the hour meter or get a stuck one working again by giving it a smack or three or four through the guts of the lamp-house with something thin, hard and heavy.The lamp used to be a Panavision rental.
Maybe if the Hobbs meter has become stuck, the user can then haggle over an estimation of the burn time. But then again, I may be unfairly ascribing deceitful behaviour.
Bob Hart November 5th, 2015, 12:08 PM Where its at.
Given the panel work on the lamphouse is thin metal, there is not much scope for rust to continue untreated before the panel becomes shotholed someplace. There was also flaking rust found in the bottom of the lamphouse after it was opened up.
Loose rust and dust do not do a lot for the longevity of hot globes.
I put the stripped parts in for sandblasting. I was going to have them powder-coated but was advised the material would not tolerate the heat in the immediate working area of the globe and might give off smoke and vapors which might shorten globe life.
The carriage and frame of the lamp holder have therefore been finished with automotive high temperature paint to avoid rust recurring. The original finish appeared to be something similar or might just have been simple stove black.
The rest of the interior of the lamp-house beneath the internal heat shields is being done with conventional enamel finishes.
No all I have to do is put it back together without having any spare parts left over and wait for the replacement heat resistant wiring and sleeves to arrive.
Bob Hart November 8th, 2015, 10:05 AM THE 12K LAMP SAGA.
Cometh the time to deal with the heat shields. They're made of some sort of woven fibre and resin stuff which looks like munted printed circuit board on roids.
They are a bit tatty and being a little asbestos-paranoid, I don't really like the look of free fibre here and there on perished edges. For sake of re-assurance it will be finished over with high-temperature heat resistant automotive paint.
I shall have to shove a bunch of industrial lights inside the thing to cook it off before I light up an expensive quartz globe in it. If there are any lighting guys out there who see me making a craven fool of myself, please feel free to convey advice, which will be much appreciated.
Sander Vreuls November 8th, 2015, 02:56 PM My military vehicle had asbestos around the exhaust pipes, which can get pretty hot, you can get modern fiberglass style protective stuff to rewrap exhausts now.. it might help here too :)
Bob Hart November 9th, 2015, 10:37 AM Sander.
Thank you for your response. I was able to find on Amazon after following a lead given me, some heat resistant fibreglass wrapping tape, which should work for wrapping bare ends and chafe points.
Chris Medico November 9th, 2015, 05:56 PM FYI - The ceramic fabrics are AWESOME! Like really awesome.
Bob Hart November 10th, 2015, 02:35 AM THE 12K LAMP SAGA. CONT'D.
Some stuff has arrived so the rest likely is due soon.
As for the lamphouse difficulties, it gets bettered and betterer. Some time in the past it seems somebody might have done a Tarzan on the big turnscrews which lock off the lamp tilt. The captive nut threads have been stripped and replaced with some cruelbad self-threading steel bush, an early evolution of the helicoil principle and what a dog it is. Leastways it is no longer waiting in well hid ambush to fail. I always wondered why it seemed loose. Now I know. Very gratified it is not going to come unstuck and come down on some poor sod's dome. A flat head is not a good look. Not quite sure how I'm going to fix this one. There's now too much missing diameter for a modern helicoil solution. If I go near it with a welder, then that new heat paint is for nought.
Chris Medico November 10th, 2015, 05:35 AM How hot does that part get with the lamp in operation? If it doesn't get more than a few hundred degrees F you may be able to fill it with a high strength epoxy such as "JB Weld" then drill and tap a new thread in there. Alternatively you can use the "JB Weld" to fuse in a thread insert.
I have used this stuff on engine blocks to repair cracks and leaks. Even a refrigerant leak in my heat pump has been repaired with it. Pretty amazing stuff. The temp limit is listed as 550F.
J-B Weld Twin Tube | J-B Weld (http://www.jbweld.com/collections/all/products/j-b-weld-twin-tube)
Bob Hart November 10th, 2015, 08:36 AM Chris.
After using a but of heat and two pairs of vice grips I managed to extract the bolts from the threaded insert.
Interestingly it appears to be an old technique. a threaded sleeve carrying the old bolt thread is fed into a widened hole. I may have been misguided as to whether this thing tapped its own thread inside the original stripped captive nut.
After cleaning it up and carefully restoring the threads on the bolt and the insert which had become galled and deformed, there were to be seen four little square-cut channels of about 0.7mm. In each of these was a sheared off miniature woodruff key. It seems that once the threaded sleeve repair was screwed in, the woodruff keys were driven in to lock the sleeve.
When the original repair was done, the bolts were installed through holes drilled through the resin/fibre heat shields on the side walls. The downside of welding ordinary nuts onto a frame as captive nuts is that they both soften with the heat and shrink narrower. They are more likely to seize and strip threads.
If a tiny dag of weld flies in and fuses, then as the bolt is screwed through against what is thought to be the resistance of shrinkage, the threads on both will be permanently modified. The bolt and nut will continue working but only as a matched pair.
The bolt heads in the original repair had been pulled down onto the heat shield material which is not metal-hard. Use has fretted it and the bolts have become loose enough to wobble but fortunately not enough to turn.
I have re-assembled it as originally repaired with hardened shoe tacks as wedge keys and tightened the bolt head firmly down onto the inside of the frame where it should have been in the first place. That arrangement seems to be holding tight. There is a tiny dose of Loctite in there for good measure. The bolts are in effect fixed studs through the frame and facing outwards.
I imagine that in original assembly the yoke went on before the bolts were inserted and pulled down from the inside. Getting it on and off by springing it over the "studs" is grunt labour but it can be done. If the threaded sleeve eventually works loose again, I'll capture it with a small spot weld.
Bob Hart November 10th, 2015, 11:57 AM Here it is in its skeletal state
Bob Hart November 18th, 2015, 12:18 PM Time for first try. Switch on. Nothing. Switch off. Switch on again. Nothing. Turns out a little rocker switch, which should switch on, no longer switches on, just feels like it does.
Here's hoping this easy trouble-shoot is not Murphy setting me up for a bigger headache. A bonus really because that switch has never been used in the whole history of the light since I have had it because it is normally out of reach with the lamp on a high stand.
So probably it laid down on being tested for the first time. Hopefully one more little ambush avoided when it counts.
Chris Medico November 18th, 2015, 05:07 PM Here it is in its skeletal state
You are going all the way. No doubt about it!
Bob Hart November 19th, 2015, 04:03 AM The latest in the adventure. There was a dead shutoff switch. The switches in the back of the lamphouse are momentary triggers. One is normally open and connects when operated and signals the ballast to strike the lamp strike. The other is normally connected and opens when operated to signal the ballast to kill the lamp. It is wired in series with the door safety switch.
The second switch is proving to be a mission to find a replacement for. For the meantime I have taken the broken switch apart and repaired it.
Set is all up and tested again. The old globe is really old, as in well past use-by. The envelope is full of dust holes, the gap is wider than it should be and the internal conductors have begun to crack the envelope near the ends. Obviously it should not be used. It strikes but is too much of a burden on the ballast which will drive it for a while but eventually will trip, not a good way to be treating an electronic ballast.
So having got the test out of the way, with everything nice, clean, shiny and well connected, the new globe could go in. - Wrong move. The new globe was gassy, went black in a heartbeat and would not strike at all.
When I bought it, I thought "GE, a good reputable US brand". Yep. Let's get this one. Then I discovered the globe is by an outfit called Koto. Any warranty is way expired as the globe has been stored for three years. Any chance of getting a replace by good grace is also gone. The Outfit "Koto" appears to be no longer making the item. No prize for guessing why.
So, any recommendations on 12K HMI double-ended globes, which are not about to lay down. They are a bit too expensive to be buying as garden curios or cute pretties to park the mantle shelf as novelty ornaments.
Bob Hart November 24th, 2015, 04:46 AM The long road is done. The appliance is closed up and the yoke back on without any spare parts that were not replaced on purpose. A bonus was that a "spare" part found inside the electrical enclosure was in fact the missing anti-friction bearing one of the yoke pivots. Now to build some funds for a replacement globe.
Bob Hart November 29th, 2015, 01:18 AM The reflector did not look quite right. The four tiny screws which hold it to the frame are 3mm. One screw on being unfastened turned and turned and turned and turned but come out it wouldn't. The reflector looks a bit dented and gouged, so may have been straightened out after a bulb explosion. The dodgey screw turns out to be a something from somewhere else. It seems it was forced. Out with the 3mm x 50 thread tap and four new screws later. Add two 6mm dome nuts to the back of the spot-flood carriage where uncovered sharp screw ends had worn through one of the old cable sleeves. Some stove window gasket to remount the fresnel glass and a lick of paint and the door's done. Lots of evidence of past hasty patchups and gettum-goes. I guess that happens over thirty years of use.
Bob Hart December 12th, 2015, 09:13 AM THE 12K HMI LAMP SAGA. CONT'D.
There was an apparently insoluble problem encountered and one knew not which way to turn. It looked like being expensive. However the guru of all things "Lightmaker" branded, Gilbert Navarro of Galaxy Repair Service in the US west coast, generously put me right on track to getting it fixed.
So it lives again to burn moths another day. A double-bonus. A breeder rat has been hanging around this past two weeks or so. It has been trying to eat its way into the lamphouse through sheet metal to get at the nice new glassfibre cable sleeves for nesting material. It met the electric trap last night. So what sort of a bizarre world is it when you end up using a 12K lamp for rat bait?
As another bonus, the three years old G.E. globe, which was thought to be a dud from new, apparently was just a hard starter and has also come good after a fair few tries to light it up. The hard start in combination with the other glitch is what caused it to be apparently moribund. So fair's fair. It should be said, the G.E. globe has turned out to be okay.
Bob Hart December 13th, 2015, 02:53 PM It lives. Local friend checking the lamp with his colour temp meter.
12K HMI LAMP COLOUR METERING TEST - YouTube
Bob Hart December 29th, 2015, 10:53 AM The final installment,the lamp on a production meeting its purpose and without being consumed by catastrophe.
There is implied non-disclosure regarding the project, an indie being filmed in Western Australia. This much by way of image can do no harm.
Thanks again to contributors of advice and knowledge here at dvinfo and at reduser for making this happen.
All the best for the New Year one and all.
Bob Hart August 19th, 2016, 05:11 AM A few months down the track and the edit of the indie movie "3RD NIGHT", for which I was tasked to shoot some BTS footage is now closer to lock off. This is the project the Desisti HMI lamp was restored for. Most of the exterior night work was lit with 1.2K, 2.4K HMI and a selection of modern LED lamps which worked a lot better than I thought they would. The big Desisti was used for moonlight effect on large areas for a few shots.
Here is the first teaser.
3RD NIGHT MOVIE OFFICIAL TEASER TRAILER 1 - YouTube
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