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Author Topic: DC ammeter on lamphouses- a must or not? Luciano Brigite Master Film Handler Posts: 277 From: Sao Paulo, SP, Brazil Registered: Jan 2002 posted 05-21-2003 07:18 PM                     Hello all, I'm on the final stage of setting up a pair of GK President lamphouses and I've been wondering lately if the current metter is really a must or not. these LH's doesn't have any metter nor have any cutting in the panels to fit one. The rectifiers also doesn't have the metters ( both rectfiers made by myself). The reason I'm asking about it is because the prices of them. I know that there are some direct metters ( that won't need a shunt) but they're hard to find. the standard ones ( that requires a shunt) I can find easy, for about $25.00 each. but the kick comes with the shunt.. it'll cost around 3 times the price of the panel metter . the only direct ammeter I have right now is marking 40 amps all alone ( and no.. it's just there standing on the bench hooked to.. nothing) and the std type ( with shunt) is only up to 75A. my last resource is the metter from a peerless, it'll go up to 110A but will look odd on the Gk lamp.. but I have only one..and two LH's any hint? Thanks!  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 05-21-2003 07:40 PM                     All the GK presidents I ever worked on had a ampmeter  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 05-21-2003 08:19 PM                     It would be a very good idea to have an ammeter on the lamphouse. If calibrated, it can be a very good troubleshooting aid in case something went wrong. It also gives a very good idea if you are operating within the current parameters of the bulb.  |  IP: Logged Luciano Brigite Master Film Handler Posts: 277 From: Sao Paulo, SP, Brazil Registered: Jan 2002 posted 05-21-2003 08:48 PM                     Hello, That's a little strange but none of my Gk president or the ones I saw/worked with have/had ammeters and the manual I have for it also doesn't show any nor has any mention of one anywhere ( the manual I found here on Film Tech).I have pictures of it but when I tried to scan, my scanner went poop on me. I ended taking a picture of the picture with the webcam, then sorry for the poor image, it's from the rear of LH where an ammeter should be located, it's before I took it down for re-paint/rebuilt and xenon conversion. The two fuse blocks on the lower left are gone and it's there I'm planning to put the ammeter. the black square at the top is a dark green glass and was kept there.  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 05-21-2003 10:52 PM                     It may have been an option, or someone removed them. I personally feel very uncomfortable operating a carbon arc lamp or a Xenon lamp that is not equipped with an ammeter. One never knows what idiot may have come in the booth and said, "Duh, what a pretty knob. I wonder what it does?" and they give it a "spin" to see what it does. Then they forget where it was.....or just leave it in a new setting. Seen it!  |  IP: Logged Stan Gunn Expert Film Handler Posts: 176 From: Clematis, in the hills near Melbourne Australia Registered: Aug 2000 posted 05-22-2003 01:19 AM                        The President lamps were never fitted with amp meters. They had a floor standing unit with the rect switchs, volt and amp meters.  |  IP: Logged Dick Prather Master Film Handler Posts: 259 From: Portland, OR, USA Registered: Feb 2002 posted 05-22-2003 01:27 AM                     Mayby the GK President lamps sold to North America had them. I agree with Gordon that all the ones I have seen had the meter. They were all in Vancouver, British Columbia and vacinity. The one I have in my basement has one.  |  IP: Logged Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 05-22-2003 01:58 AM                        Also, make sure that if you do have an ammeter, it is of the correct sort and working properly. At one cinema I worked we couldn't work out why lamps were only lasting 1,000 hours or so before dying of a badly blackened envelope and/or a charred anode lead. After months of head-scratching, the answer turned out to be that the ammeter was of the wrong sort, and giving a reading which was way too low. We thought we were running the lamp at 65-70 amps when in fact it was doing 110-120. Needless to say, that explanied why we were nuking the bulbs, and also why the picture looked nice and bright!  |  IP: Logged Stephen Furley Film God Posts: 3059 From: Coulsdon, Croydon, England Registered: May 2002 posted 05-22-2003 02:42 AM                     Paul wrote: quote: I personally feel very uncomfortable operating a carbon arc lamp or a Xenon lamp that is not equipped with an ammeter. With xenons, I wouldn't want to run without meters on the lamphouses, though ones on the rectifiers are a reasonable substitute, if the rectifiers are in the projection box. If they are in a separate rectifier room, then meters on the lamps, or at least somewhere in the box, are a must. I don't feel that they are as necessary with carbon arcs, there is no risk of explosion, and you can normally tell by noise, carbon consumption, etc., if a lamp is running much above its normal current. One exception might be with very high powered lamps, running at close to the limit of what the film can stand, where even a small overcurrent might be enough to damage the print, but I'e never fun anything above 75 Amps. Agree with Leo, check the calibration.  |  IP: Logged Peter Hall Master Film Handler Posts: 314 From: London, UK Registered: Dec 2000 posted 05-22-2003 07:26 AM                        Have to add to Leo's post - even at 120 odd amps, with a VERY bright image (I'm sure the apt operators didn't increase the curreny beyond what was needed to get 16FL) the Superior Quartz lamps in that screen almost reached their warranty hours ! Not bad really - maybe a case for a low cost, ultra compact 3k lamp !  |  IP: Logged Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 05-22-2003 08:44 AM                        quote: I'm sure the apt operators didn't increase the curreny beyond what was needed to get 16FL In retrospect I'm sure we did. Screen luminance is a bit difficult to judge subjectively and without a spot photometer, especially when lots of (differently graded) prints are passing through (so in effect you're trying to judge a moving target) and we'd never seen that screen with a lower illumination level. Needless to say the difference was startlingly obvious when the correct ammeters were in and the current was back down to 70, though... It's for that reason that I'd be very cagey about ever operating a lamphouse without a verifiably kosher ammeter: if you suspect that something's wrong with the power supply, there is no other way of checking it objectively unless you have a light meter (which most cinemas don't) or you're willing to take the cover off a live rectifier and poke a very high-spec multimeter up its innards. Call me a wuss if you like, but I think I'd pass on that one!  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 05-22-2003 09:03 AM                     If you notice that black bar below the rear view port with the two holed that is where the surface mount meter went the two stud of the connection went through two porcelain bushings andthe shunt was mounted across the back Considering how many were sold (very popular lamphouse and very efficient) I would be suprised that they were not on all of them  |  IP: Logged Jim Spohn Film Handler Posts: 95 From: Bakersfield, CA, USA Registered: Jan 2003 posted 05-22-2003 10:16 AM                     In a pinch, amp-clamps will give a pretty good idea of how many amps you are pulling. (Yes they will work on DC) You might also find an ammeter on an old carbon arc lamp, it will have the proper shunt on it for the meter. The shunt goes across the meter and the meter goes in series with the load....Jim  |  IP: Logged Luciano Brigite Master Film Handler Posts: 277 From: Sao Paulo, SP, Brazil Registered: Jan 2002 posted 05-22-2003 05:47 PM                     Hello again, thanks for all the information until now. The black bar bellow the rear view port has the switchs for the inspection lamp and the feed motors, what they control is written on that bar.( that bad pic. I posted isn't showing it clearly). I have a clamp meter,bought it mostly to take dc current readings after reading somewhere here in the forum about that same situation Leo mentioned ( I believe it was his own post i read at the time about it) anf after had about the same problem once with a bad ammeter ( it'd stick at about the 70 amps while the real current was reaching the end of scale, 100A). The only ammeter I have that'll fit the 2000W bulb range is one from a peerless lamp ( up to 110A), but I have only one, it's working ok and is in good shape. I'm looking for another one ( or maybe for a new pair of them) if I can't find.. I'll have to find a place that sells ammeters for a fair price. Thanks!  |  IP: Logged John Spooner Expert Film Handler Posts: 186 From: South Australia, Australia Registered: Jan 2003 posted 05-23-2003 12:23 PM                     Dear Luciano and interested parties. Here is a picture of an original Gaumont Kalee President carbon arc lamp (with Kalee 21 head). The amp meter was mounted on the pedestal directly under the lamp. John S.  |  IP: Logged

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