Conventional Fixtures Strand Fresnelite bases

Pdnate

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Jul 18, 2013
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Hi all, I have about 30 Strand 6" Fresnelites that I have been replacing bases on more frequently than I think necessary. The problem appears to be arcing with carbon build up between the bottom of the lamp base and the spring loaded connector in the base. I have tried different brands of porcelain bases (currently getting them from Grainger) and I have even been re-wiring them with high temp wiring. I am now wondering if there is a problem with the distance between the lamp bases and the spring loaded base connector. Has anyone had any experience or luck repairing these things. It is not in the budget to just buy new fixtures. Thanks.
 

derekleffew

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gafftapegreenia

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Trust me, when you go to an industrial lighting supply warehouse and ask if they have MPF bases they look at you funny.

That said, three things:

You can’t reuse a lamp that’s been in an arcing socket, it spreads the diseases.

Is there a replacement for the old Bryant socket with a flat bottom contact? Last time I was in this situation (and mind you it’s been about 5 years) the only sockets on the market had cup shaped center contacts.

Lamps also changed in the last decade to a small center for contact instead of a nice big solder blob.
 
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JonCarter

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If you're dealing with prefocus lamp sockets, either medium or mogul, the lamp base contact and tops of the base flanges make contact with the spring-loaded center contact and the undersides of the flange mating surfaces of the socket. These two surfaces are under the pressure of the base contact spring. Be sure the mating surfaces in the socket (which you can't see, being the bottoms of the flange facing surfaces ) and the base contact are clean and the spring on the base contact has not lost tension.
 

ship

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You can at times clean a bad P-28s based lamp center pin. (Medium Pre-Focus) You can also do so for P-40s G-12, G-38, E-26 and E-39 lamp bases safely. It's just the little bi-Pins from G-9.5 to G-4 that won't work well. It will some times work on R-7s (RSC) bases if you use the dremmel.)

Takes a silicone abrasive grinder wheel (Bench or right angle) or the same type of cone sanding wheel for a Dremmel (though the Dremmel won't do as good of a job, too small of surface contact.) There is also lots of nylon mesh polishing pads some even like Scotch Brite Pads for right angle grinders, drills and Dremels (grinder ones are good but wear out fast, drill polishers are mostly too slow and won't do as good a job - use only where a grinder won't get to like a pipe and a Dremel would be like painting a wall with a pencil - won't do a good job. And that's why your use Dremels on lamp sockets (small areas) and not larger areas. Most of these pads say they are for soft materials.... ingnore that, this is why they remove light surface corrosion & smooth pitting but don't dig into the metal much.

Such "fine" grit polishing/sanding pads remove corrosion and light arching to a mirror like conductive finish fairly quickly without grinding deeply into the metal or solder making up the button of the lamp base. If you need to remove a little more material or weld blobs there is other less fine bits or pads or cones that can be used - these items are not to remove much damaged material but will remove some where needed to flaten a lightly pitted plate. After polishing, you must treat the freshly exposed metals or it will oxidize and resist conducting.

If there is corrosion on the (Neutral) outer shell, you can use Chrocus Cloth or very fine steel wool. Chrocus Cloth is better and what I would also use on G-12 or G-38 pins. Dremmel EZ Lock Silicone nylon mesh (fine) are also really useful for cleaning the shell to a P-28s or E-28 and or P-40s or E-39 lamp socket. They work much better than a brass wire dremmel wheel on a lamp base shell.

High temp DeOxident - Especially Craig's with copper has been recommended, I use Sprayon #EL2001 Electrical Contact Cleaner & Protectant for up to 5Kw lamps. Clean the halogen lamp globe with denatured alcohol and a lens or clean room whipe after done.

McMaster Carr part numbers cited above:
4721a11 - 4.1/2" Angle Grinder disc. Also useful for Leko Shutters, Followspot Choppers & Dousers, and with a jig - individual Iris leafs. Don't forget to polish the leading edge of what you are polishing. If careful you can easily clean especially a P-28s lamp socket base tip with it. A light swipe across the material than have a look to see if another pass or more and where needed until practiced at agressiveness or not is a good thing. Different than grinding - takes practice or you will overheat what you are polishing.

4763a13 I believe this is similar to the Nylon Mesh 2" Bench Grinder Wheel I use, I also have a 1" wide 4763a12 at work which I don't recommend - gets eaten up too fast by barbarians. Useful that size also, but keep an eye on who is using either and for what.... it's not a grinder wheel!!! Difference in the current wheels offered and what I have are mine are beige - McMaster wheels are gray so they might not be exactually the same, but description is similar so they should work. Also useful for cleaning up Buss bars, contacts for follow spot lamp bases, plates of conductive material, getting a chisel or knife extra sharp if used properly etc.

46835A11 Nylon Mesh Cushioned Sanding Bit, 1/4" Diameter x 2" Long Shank, 2" Diameter, Fine Grade (Though Memards has scotch brite flap sanders that do a good job.) 3127A78 12" Long Extension for 1/4" Hex-Shank Drill Bit = needed.

4630A173 Nylon Mesh Cushioned Sanding Bit, 1/8" Diameter x 1-1/2" Long Shank, Shape No. W163, Fine

4630A193 Nylon Mesh Cushioned Sanding Bit, 1/8" Diameter x 1-1/2" Long Shank, Shape No. W185, Fine

4630A133 Nylon Mesh Cushioned Sanding Bit, 1/8" Diameter x 1-1/2" Long Shank, Shape No. B52, Fine

7437k15 Electrical Contact Cleaner w. Lubericant 16oz. Spray

Add to the shopping list:

1289K17 Dry-Film Penetrating Lubricant for Chain, 10 oz. Aerosol Can 2

13725K12 Dry-Film Penetrating Lubricant for Wire Rope and Cable, 3 oz. Aerosol Can 1

7089T31 Polyester/Cellulose Clean Room Wipe 4" X 4", Packs of 300
 
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ship

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Mar 29, 2003
Location
Illinois
"Hi all, I have about 30 Strand 6" Fresnelites that I have been replacing bases on more frequently than I think necessary. The problem appears to be arcing with carbon build up between the bottom of the lamp base and the spring loaded connector in the base. I have tried different brands of porcelain bases (currently getting them from Grainger) and I have even been re-wiring them with high temp wiring. I am now wondering if there is a problem with the distance between the lamp bases and the spring loaded base connector. Has anyone had any experience or luck repairing these things. It is not in the budget to just buy new fixtures. Thanks."

Had a CamLoc to 6x L21-30R AC Distro come back today with a melt down on the black CamLock from panel mount melted into it's plastic shell, thru the outer jacket of the 2/0 SC. Scorched buss bar linking the CamLoc feed thru and it's nut's/lock washers turned green with corrosion. No... Doesn't have to be weather to turn something green and corroded. All other nuts from 2/0 wire to the CamLoc were tight, but the one in question while not loose, came loose somewhat easily. Question came up from one of my assistants.... "Did our supplier of this distro screw up again in forgetting to tighten a lug nut on the CamLoc?" While a very high profile AC distro company... my department somehow always seems to wind up with their mistakes - frequently. This corroded lug did seem to loosen easier than others, but perhaps that expansion/contraction and corrosion was a factor in this. Had a thought, in that all the other lugs were tight and there was melting of the plastic around the inlet CamLoc, what if it was not this Distro that caused the problem but the cable feeding it? Nobody turned in for repair that cable and the cable dpt. is searching for that missing cable. (Hmm tracking of gear and serial numbers is useful.) Until I see the feeder cable that plugged into this distro - which would have heat damage also anyway and need replacement, the cause of the problem cannot be determined for sure. But I think the cable failed for now.

Why I say this above is that it's related to your problem, if you put a bad lamp into a perfectly good socket, it makes for a perfectly bad socket. If you than put a perfectly good lamp into a bad socket, it becomes a bad lamp. If you than put that lamp into another socket.... You see the problem.

Grainger sells P-28s lamp sockets? What's it's part number, very curious in another source. What brand do they sell?

Punch list:
-What wattage of lamp are you using?
-Selcon fixtures are too new to be having spring problems.
-Are you also going thru lamps left and right or just re-installing as above post disease (sounds familiar in initial term used.)?
-I note you are re-wiring with high temp. wiring - what spcific wire and gauge of it are you using? Why is the need for re-wiring is it also melting down? (Photos.)
-What type of crimp terminals are you using given most P-28s lamp sockets mostly no longer allow the terminal screws removabable so as to use high temperature ring terminals and lock washers? Are you using perhaps cut for a slot high temperature ring - now fork terminals, standard fork terminals or shoving bare stranded wire under the screw terminals?
-Can you take a photo of these connections and the crimpers and terminals used if any?
-Screws on the lamp socket sometimes loosen especially if touring by way bouncing about in a truck around the world or expansion/contraction from heat. Fine stranded heat wire can settle inside a crimp termial if not crimped properly with presser or the correct tool, this much less if installed directly under a terminal screw. Such even slightly loose screws can cause a bad lamp socket but doubt your situation.
-Photos of the bad lamp sockets in where arching heat discolored etc. and replaced wiring is helpful.
 

Pdnate

Member
Joined
Jul 18, 2013
Location
Southern California
"Hi all, I have about 30 Strand 6" Fresnelites that I have been replacing bases on more frequently than I think necessary. The problem appears to be arcing with carbon build up between the bottom of the lamp base and the spring loaded connector in the base. I have tried different brands of porcelain bases (currently getting them from Grainger) and I have even been re-wiring them with high temp wiring. I am now wondering if there is a problem with the distance between the lamp bases and the spring loaded base connector. Has anyone had any experience or luck repairing these things. It is not in the budget to just buy new fixtures. Thanks."

Had a CamLoc to 6x L21-30R AC Distro come back today with a melt down on the black CamLock from panel mount melted into it's plastic shell, thru the outer jacket of the 2/0 SC. Scorched buss bar linking the CamLoc feed thru and it's nut's/lock washers turned green with corrosion. No... Doesn't have to be weather to turn something green and corroded. All other nuts from 2/0 wire to the CamLoc were tight, but the one in question while not loose, came loose somewhat easily. Question came up from one of my assistants.... "Did our supplier of this distro screw up again in forgetting to tighten a lug nut on the CamLoc?" While a very high profile AC distro company... my department somehow always seems to wind up with their mistakes - frequently. This corroded lug did seem to loosen easier than others, but perhaps that expansion/contraction and corrosion was a factor in this. Had a thought, in that all the other lugs were tight and there was melting of the plastic around the inlet CamLoc, what if it was not this Distro that caused the problem but the cable feeding it? Nobody turned in for repair that cable and the cable dpt. is searching for that missing cable. (Hmm tracking of gear and serial numbers is useful.) Until I see the feeder cable that plugged into this distro - which would have heat damage also anyway and need replacement, the cause of the problem cannot be determined for sure. But I think the cable failed for now.

Why I say this above is that it's related to your problem, if you put a bad lamp into a perfectly good socket, it makes for a perfectly bad socket. If you than put a perfectly good lamp into a bad socket, it becomes a bad lamp. If you than put that lamp into another socket.... You see the problem.

Grainger sells P-28s lamp sockets? What's it's part number, very curious in another source. What brand do they sell?

Punch list:
-What wattage of lamp are you using?
-Selcon fixtures are too new to be having spring problems.
-Are you also going thru lamps left and right or just re-installing as above post disease (sounds familiar in initial term used.)?
-I note you are re-wiring with high temp. wiring - what spcific wire and gauge of it are you using? Why is the need for re-wiring is it also melting down? (Photos.)
-What type of crimp terminals are you using given most P-28s lamp sockets mostly no longer allow the terminal screws removabable so as to use high temperature ring terminals and lock washers? Are you using perhaps cut for a slot high temperature ring - now fork terminals, standard fork terminals or shoving bare stranded wire under the screw terminals?
-Can you take a photo of these connections and the crimpers and terminals used if any?
-Screws on the lamp socket sometimes loosen especially if touring by way bouncing about in a truck around the world or expansion/contraction from heat. Fine stranded heat wire can settle inside a crimp termial if not crimped properly with presser or the correct tool, this much less if installed directly under a terminal screw. Such even slightly loose screws can cause a bad lamp socket but doubt your situation.
-Photos of the bad lamp sockets in where arching heat discolored etc. and replaced wiring is helpful.
Some answers to your questions:
Wattage is 1K
Going through lamps like they were water
Wire I am using is BNTECHGO 12 Gauge Silicone Wire
I have to modify my connectors to fit in the sockets
The Grainger info is: Bryant Electric R13742 A; item #46587835
I'll try and get photos soon.
 

ship

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Mar 29, 2003
Location
Illinois
Stranding of wire in not SF-2 defined as normal is very flexible a good crimp to a terminal Briant (non-removable) screw should work if the brightwork contacts to the lamp is also good. And a good lamp. Very important as especially on your fine standed wire perhaps about your crimp terminal and means of crimping. Intent is good on your part, ours is to see what the problem is which should not be in finding it. You have a problem not solved as to the cause.

"I have to modify my connectors to fit in the sockets" - further define what you mean. Cutting a slot into a ring terminal so as to make it fork terminal, or in general are you also replacing the above wiring and how on the not related end terminated to the whip?
 

Pdnate

Member
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Jul 18, 2013
Location
Southern California
Thought I would jump in to this older post of mine. I have replaced bases on my Fresnel stock. The problem is simply in the old days the spring contact was a flat surface. The newer ones are concave. The lamp contact points don't always have the mass to completely make good contact. An Electrical contractor friend told me about Ideal Noalox, an electrical contact anti-oxidant compound. It is conductive and "fills" the gaps so to speak. It does not harden. It seems to be doing the deed. Thanks to all that originally responded and check out the Noalox. It is a great little item and can be purchased at Home Depot.
 

ship

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Mar 29, 2003
Location
Illinois
Surface contact area is surface contact area, as with spring tension on lamp sockets of cup or flat center contact types.. is tension and dependant on that spring tension. Overall it's the spring and a clean contact surface.

A lamp with a bean for it's contact probably won't conduct to a flat surface as well as a lamp with a flat plate unless by design that bean tip puts a little more length thus tension on the contact pad for better conduct of energy. (Don't know for sure but I think the bean tip of such a lamp sticks out a little longer in doing this.) Were there no added length in the bean lamp socket base, such a cup on new lamp sockets would have no advantage.

The flat plate lamp base, might be fine per lamp supplier supplying the bean base lamp. (I certainly have no idea unless I check stock of what brand is bean verses flat plate... might be Ushio as bean as a guess?).
It's also potentially a tension issue on a smaller lamp surface area either solved or not by lesser spring tension on older sockets. On the other hand, a flat base lamp socket will also have even if surface area advantages, problems if that spring is not sufficient in tension. Or the lamp socket corroded for contact in both cases.

A lamp with a bean base fitting into a cup also has a small surface area - and I have seen this a problem also with weaker springs.

Where are we in my comment...?

Don't install a perfectly good lamp into a bad lamp socket - and you can look at the bad lamp in indicating a bad lamp socket. If the spring on any of this type of lamp socket is springie enough for tension, either type cup or flat plate lamp socket if in good condition should be fine for either style of lamp. Lamp type bean or flat plat should not matter, as with cup type or flat plate lamp socket if in good condition.


Be very glad that the G-22 version of Leko lamp went out of style for some reason I think during the ladder part of the 1950's as opposed to the P-28s.... I See a lot of versions of fixture either/or in choice between lamp socket during that period of time. The G-22, is a great lamp base platform, but the lamp socket was not good... (They suck for that period of Leko!)

Almost no relation to a Fresnel in historical data, except around 1964 the RSC (R-7s) based halogen lamp for theater lights was invented for Leko's and Fresnels, (Kliegl or Colortran), and in the next few years the Quartz upgrade in a halogen double ended lamp about almost ended that of the P-28s single ended lamp concept currently in use, especially in Fresnels over the next ten years.
 

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