ETC Source Four Socket Problem


We have a set of 8 yr old Altman Shakespeares that we’ve never done anything to or with that was more complicated than changing the lamps. Ditto for a set of six-year old Strand ellipsoidals, but not so for our set of 62 six-year old source fours. For the last couple of years, a couple of sockets per six-week run would need to be taken apart, have the three prongs on the lamp contact cup rebent and put back together.

When the problem became 2 bad sockets per performance setting an all-time record of 5 bad sockets for one performance, it really got our attention.

First, why were we suddenly having more problems than before?
Second, why do the source four sockets appear to need more maintenance than other TP22 sockets and has this been everyone else’s experience too?
Third, what can be done to remedy the problem?

Had you asked me a month ago if I had ever encountered a TP22 socket that couldn’t be fixed, I would have said only when one of the prongs on the cup had broken off. Had you asked me a month ago why we were having more problems now than before, I would have said that since the instruments were all purchased at the same time, it wasn’t particularly surprising that they were all having problems at the same time.

But here’s the interesting part. Someone else between April and November decided to replace any bad sockets and not bother trying to repair them and our current problems, although it took a while to realize this, are predominantly with these new (ETC M709) replacement sockets and not so much with the old original sockets, which can still be repaired as described. The design of the replacement sockets has changed to include a wire ring around the top of the cups, which appears to be part of the problem, and although we can repair them, they fail again within one or two performances.

This has led us to begin a number of experiments. We put in an ETC 750 socket (even though we don’t use 750w lamps and rarely run our 500w lamps above 50) to see if we got better results. We opened up a Sylvania TP22 socket and removed the leads and put them in a source four, but they are about 6 inches shorter, which means we had to cut back our cord, which we’d rather not do unless we have to. We opened up a Ushio socket and put both its leads and its porcelain in a source four (a somewhat snug fit since the porcelain is slightly thicker and the cups noticeably longer). We also cut slivers (1/8” x 3/8”) of sheet aluminum and put them between the back of the etc cups and the mica to try to push the cups higher into the porcelain on the assumption that perhaps the pins on the lamps were only making partial contact at their very tips.

It’s too soon for us to have any reliable results yet. Has anyone else been down this road? Has anyone else encountered similar problems?


Active Member
I've never experienced any problems with our S4's but I have had plenty of problems with our Altman sockets. It is very easy in the Altman socket for the bulb to not be seated all the way causing a carbon build-up and forcing us to replace the socket. Not a real expensive fix (~$15), but it's just tedious and occurs at bad times. The S4 has little arms to keep the bulb seated, which is a better design IMO.


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some of the older S4's dont have that clip which drives me crazy personaly.... and i have had the same problem with our older s4's... its relativly easy part to relace though


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I've had horrible experainces with carbon build up in the new (3 year old) s4's in my space. Don't rember the process we used to fix them though. Also you can put a 545 lamp in a 700 watt s4 and still run it at full, you just can't do the oposite.


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you can buy new leads for the s4... call any lighting supplier and they should be able to get them to you... its basicly a new socket inlit that fits in the porcelan... they are very easy to change (i did 3 tonight in about 30 min)... its a cheap and easy fix... also you can get retainer clips for older s4's that dont have them....


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My first question beyond - wow, way more dangerous than I would ever attempt, would be did you put brand new lamps in the base or attempt to install potentially trashed lamps by way of base/pin into the new sockets.

Beyond this, wow, what the heck are you attempting to do here?

You know way back when Philips came out with a GLA/GLC with heat sink conversion for their lamps to fit into a ETC S-4 Leko, that’s about the messing with lamp base I might attempt. Yep, did the FEL into a S-4 given the removable sink installed on the FEL. Not pretty.

You talk about base contacts and mica of a S-4 and Ushio or other TP-22 contacts installed into a ETC fixture and I only stand back and ask why on such a thing.

Yep, of a lot number and series of fixture bought at the same time, you can often expect a cascade of problems as initial assumption with all. Experimentating to solve the problem better on the other hand can and should be done but without better results should be assumed not to be best when as different as you note. Didn’t fit - a aluminum piece as a spacer... perhaps it fitting now but later flopping around inside the lamp base caused the problem. Hate to see what would happen should two such spacers touch inside the base.

On the TP-22 base, the Ushio base at this point is not a recognized lamp base to use on them. There is a few brands Altman does recognize for use in their fixture, Ushio at the moment is not one of them. The Shakespear lamp base in TP-22 form has low and high temperature lamp bases of upgraded and old style forms. The Ushio while exactly similar to the most modern of upgraded bases still is not UL listed or recognized for use in an Altman fixture. This much less once dissemembled and used in a ETC fixture.

G-9.5 Altman #97-1580 Med. Bi-Pin Lamp Base, Porc. (Newest Style)TP-22, 1000w/250deg. c. Socket As #58-0018
G 9.5 Altman #97-1570 Med. Bi-Pin Lamp Base, Porc. (Newest Style) TP-22, Lower Temp. Leads. As #58-0017
C3A, G9.5 Ushio #1000113 Med. Bi-Pin Lamp Base, Porc.
G-9.5 Altman #58-0018 Med. Bi-Pin Lamp Base, Heat Sink (Old Style) (TP-220)
G-9.5 (Disc.) Altman #58-0017 Med. Bi-Pin Lamp Base, Old Style TP-22 Socket

That retaining ring above the contacts on the ETC base is also not the cause. This rig keeps the socket together.

In repair of either of these G-9.5 bases, there is not much repair you can do to them. It’s certainly more cost effective to just replace what goes bad. If a base goes bad before it’s time, it would be something to take up with your base or fixture supplier. No upgrade on your end by way of trying other things will work well.

6" shorter in whip,... are we talking problems with the lamp base or problems in whip.

If of any help, stop playing around with the inside of less than a G-38 lamp base. Not much you can do in re-surfacing and lots of injury you can cause. Certainly take apart and learn from the bad, but don't use as production model your experiment.


You wouldn't throw out a $5 stage pin connector just because it wasn't making a good connection in its receptacle anymore. You'd spread its pins and fix it--at least I would and I suspect you would too.

For similar reasons, there's no point in throwing out a $15 TP22 socket just because the pins on the lamp aren't making good electrical contact anymore.

From an engineering standpoint, it's the same problem. A cylindrical peg or pin is applying friction to the inside of a cylindrical hole. In one case the split pins are spread apart and in the other case the the cylinder is pinched together.

There is however another factor. Someone mentioned that when the socket is new, the contact cups look like chrome inside and out, but after they have been in the instrument for a while they look rusty. What causes this? What is this stuff? Is it affecting the conduction of electricity? And how would one clean it? Can it be prevented from coming back? Has anyone seen this mentioned or discussed in say a lighting book.

The sylvania sockets claim that the contacts are silver-plated brass. My guess is that other brands may be as well. Brass can tarnish and tarnished brass doesn't conduct electricity. I have a tarnished brass belt buckle, and I'm putting the multimeter leads on tarnished areas about 3/4" apart and am getting nothing. I also have one of the ETC leads that was removed and I can touch various places inside the cup with the active probe, and current will not pass from the connector end of the wire. We soaked this same contact in Brasso and cleaned it with a Q tip and this fixed the conducting electricity problem.

Also we have noticed that the pins and screws inside of our stage pin connectors, which are also brass appear bright and shiny and not tarnished at all. Is that a coincidence or to do they treat the brass with something or add another metal to the alloy. Does anyone know?


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You are correct in noting oxidation or carbon where resistance is concerned when not pitted or arched. On the other hand, how much is a $15.00 lamp base as compared to if even un-paid time given the lamp base has only a certain amount of life rated for it and cleaning it will only often extend that life a few hundred more hours until it comes back to visit you again how much cleaning is worth it.

Lets' see, I make more than $15.00 per hour. Were I as an expert in properly cleaning a lamp base as opposed to someone making $10.00 per hour be given this base, I would toss it out if other than an easy fix. Nuch less I also will not instruct other than at times a cleaning of the lamp base how to more properly clean if at all this size of base. How much time did it take for the $10.00 per hour person to take the fixture apart? Given it's a quick fix and you won't be able to clean much of it, how long will this extend the life of the lamp base before it becomes troublesome again? If I spend 15 minutes on this base or even shoud I teach someone at a lower pay scale to, they later are veary likely to see this base again in say a few hundred hours. Let's say a lamp base is rated for 20,000 hours. Should it fail at say 15,000 hours but only a simple cleaning be needed, how much time does this take given one will see this fixture again soon? You than add to the cost of repair, a second visit for repair where for just about the same amount of time, one could have just replaced the lamp base. Now granted chemicals and tools to clean and treat the lamp base might be cheaper than purchasing a new lamp base, add to this the cost of labor much less at times skilled labor in instruction or doing it how much it will cost once this lamp base not just visits you once but twice within the base's lifespan. How much is that worth the cost of just replacing the thing?

Yea, it's a corporate or mercinary type of attitude on this type of base but also one that banks on safety and wear.

When not too bad, your solution is a good one also peroxide might help as with other chemical cleaners. I might spray some de-natured alcohol into the lamp base and whipe clean to remove any residue that under heat can form a build up on the other hand. Otherwise it's feasible that you might clean out the old but add new problems.

Brasso should work well, ETC uses gold plated contacts by the way. Other contact treatments aganinst corrosion or heat is often nickel and silver plating. Very rare it's using a brass contact block or contact pin without a plating. If nothing else it might be bronze. Normally new lamps and bases will come with a plating you should not be messing with. It is only after you clean or even re-surface a lamp or base that you should add a coating.

A really quick way to destroy a perfectly good lamp base is to install a trashed lamp by way of it's contacts into it and visaversa. This much way a good way to destroy all your equipment is by way of lamp swapping without inspection of the lamp you remove. Always have a good look at the lamp you remove at it's pins or contacts when you remove it. This is primary and the easiest way to notate a bad lamp base, much less a lamp you should never install in another fixture. Same by the way with lamps, a lamp that costs $15.00 probably is not worth your time to do more than a carbon build up cleaning of it.

These pins should measure 3.2mmx8.4mm long. There is not a lot of pin to be working on. Short of thinning down the Q-tip, also not a lot of cleaning that can be done. Other types of lamp and lamp base, sure, I have brass wire wheels from grinder to Dremmel, and also soft fiber wheels to work on them. At the moment in fact I have a host of Fresnel lamp bases to get done and these I will work on as long as the center spring has sufficient tension to it.

I normally use McMaster Carr #7437k15 "Electrical Contact Cleaner w. Lubricant" in a 16oz spray can to treat any pins I treat from a stage pin plug shined up to up to a 5Kw fresnel. Yep I spread pins with a pin spreader, than even test to ensure the pin has not been spread too wide. I also cuss at those who paint the fixture and overspray the plug.

The other ME where I work normally uses GB brand de-oxident. I'm not a big fan of it because it dries up and becomes gummy after heating. Some in the industry I have deep respect for Ron Hebbard and Craig Leerman from ProSound amongst others in the industry prefer products from .

"One more thing I might mention; when I first decided to try CAIG, I called and spoke with a lady who was basically an applications specialist. She was very interested in making sure that I was getting the best product for my application and asked me about eight to ten questions before settling on the right combination of two products for me. This was about seven or eight years ago when I was at the point of having to replace the input faders in a Yamaha console. That console got that one application and it's still working just fine. A little seems to go a long way.

Just a few words about CAIG and how they developed some of their products. As I understand it, they were collecting the worst of the worst parts that RANE was replacing in their service department; taking those abused components, switches, potentiometers and connectors, and developing "magic" chemicals to restore them to like new performance. Everything I know about chemistry, you could put in your eye with no discomfort. I don't know how their "magic" works but it works for me.

Hope it works out well for you.
Ron Hebbard"

Others in the industry attest to a copper based de-oxident. This for me is problematic in if the fixture should get wet, cold the water cause the copper based chemical to break down and short. Other than that, a metal base to it should withstand the heat well.

This being about a lamp base that is making good electrical contact. When it's not by way of testing - the lamp should not fall out be it PAR 64 or GZX-4. The lamp base no matter the type sould not allow the lamp to wiggle out or and also be able to lift that lamp and perhaps even bounce it once without the weight of the lamp being sufficient to fall.

Yep, I have been inside a PAR 64 lamp base and squeezed together it's contacts some. Heck in the past I have even installed some quick disconnect terminals inside a MOEP (GX-16d) base base above. This was in the past when I was tinkering. Sure it worked, how long it worked on the other hand or will I have been better investing my time on other things is by far another question. At one point when Altman discontinued all of their 2Kw thru 5Kw studio Fresnel lamp bases before they came out with the upgrade, I was re-surfacing Mog BP (G-38) bases like crazy. In this I got really good. Even still almost constantly either instructing how to or doing lamp base re-surfacing. It can be done, and is done frequently, but it's probably not worth one's effort in a smaller size than say GY-16 lamp base.

In the past, yep I can remember being inside a TP-22 lamp base. Perhaps I collected up two of them and in the case of where the hot wire went bad but neutral was still in decent shape, combined two bases to make one. Probably did this in the past. These days, not a chance not just due to pay scale but because of an opinoin on my part that might not be shared, that a $15.00 lamp base (in my case perhaps a bit less) is just not worth working on given it's pin size.

On the other hand, in modifying a lamp base, a week ago I needed some rear flange RSC (R-7s) lamp bases. My noting of the metric or industry term (R-7s or say G-9.5 or G-38) is not to impress but instead to get others used to it because it will eventually become a standard. Altman was backordered on them and It was too late to do a Osram, Ushio, Buel, Stucchi, Leviton or other research task in finding one that was reverse from normal. Instead I took apart some front flange RSC bases and made them into rear flange. Somewhat tricky but also simple enough. This type of thing I will do, and I have probably been inside most lamp bases from ones stamped with the Warner Brothers logo to those off a table lamp. Little Light lamp bases (BA-9s) I run about a 10% chance of saving for instance.

My point is more that it's possibly not cost effective to be working on certain types of lamp base.
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Consider this an interim report. We are now several months down the road, and we have at least partially solved the problem, and we think we understand what caused it in the first place.

First, there were three sockets that we replaced with a sylvania socket, a ushio socket and an etc 750 fully enclosed socket. All three are doing well and have required no additional maintenance. We maligned the ring at the top of the contact cups and considered it to be part of the problem; we now think it had nothing to do with the actual problem.

We had great hopes that by putting slivers of aluminum under the cups of the standard M709 ETC 500 watt replacement leads that we could push them higher into the porcelain and get better contact with the lamp. This proved to be a stupid idea that was completely ineffective.

On the other hand, cleaning the contacts with Brasso, which we thought was at best a lame idea that probably would go nowhere, turned out to be the star of the show. On instruments that failed to work, the first remedial effort has been (using a burned out lamp as a Q-tip) to dip the contacts in Brasso and work it in and out of the socket. Since starting to do this we have not replaced another socket.

Since some of the new ETC sockets failed after 3 or 4 weeks, we think the gold-plating was either missing or badly applied or it wore off or burned off. In any event, had it been there, we doubt that the brass could have oxidized to the extent that it obviously did.

Of the replacement sockets, at this point we think the Ushio is the most promising, but it is really too soon to tell. As mentioned in the start of this thread, we have sets of Altman Shakespeares and Strand Ellipsoidals that we have had longer but have never needed any maintenance, whereas the Source Fours have not been anywhere near as reliable.

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