[SML] How to gauge the age of a Source Four?

[Dale Farmer]

Paint flaking off of the lamp cap over time is normal, and the photons 
don't care about that paint or lack thereof.   I'll speculate here, but 
I think ETC switched to a low or no VOC paint process and the different 
coatings react differently.
    Paint adhesion over time is one of those simple sounding things that 
turn out to be stupendously complicated.  formulation of the paint, 
surface preparation of the painted surface, primer, application 
conditions, curing conditions, working life conditions.  I took a dive 
into that a few years ago, and quickly bounced.   Physics and chemistry 
and manufacturing and end users all matter.

   The reflectors, they do take on a yellowish hue on the reflector 
surface over time.  This presumably changes how it reflects or passes 
the various wavelengths.  I believe this is aging of the coating, but 
that really is just a guess on my part.   It does change the light 
coming out the front, but I never had the means to actually measure it 
other than using the Mark I eyeball.  It seems a bit darker, but won't 
try to quantify it more than that.
  I will say that some fixtures that were in night clubs, before they 
banned smoking, that the yellowish tinting of the coating was stronger, 
but a vigorous cleaning removed a lot of it.
   I have no doubt that ETC's local dealership would be more than happy 
to sell you as many replacement reflectors as you care to buy.   Might 
just be easier to group the older fixtures for specials and the new ones 
for washes.

Dale

On 5/2/2020 2:03 PM, Jon Ares via Stagecraft wrote:
> I was able to go into my facilities yesterday to start prepping for a 
> buncha new fixtures, and found some interesting things, and I'm curious 
> about any other "changes" that have come to the Source Four over the 
> years...
> 
> I have some bodies that are 2015, and others that are 2006.  All use 
> 575w HPLs, some long-life, none at 750w. All the 2015s all have 
> cooked-off paint on the lamp housing.  The 2006s still look fine.
> 
> The reflectors are clean on both bodies, but the 2015 reflector has a 
> definite 'cooler' color to it... the older ones have a warmer tone. But 
> they're clean - no haze.
> 
> So have there been changes in paint?  Reflector coatings?
> 
>   - Jon
> 
> 
> On Sat, May 2, 2020 at 10:56 AM Dale Farmer via Stagecraft 
> <stagecraft at theatrical.net <mailto:stagecraft at theatrical.net>> wrote:
> 
>     The source 4 middle bodies are, afaik, unchanged from the early days.
>     Single and double yoke bolt versions were the only distinctions, I can
>     recall.
>        Reflector housings went through a couple of changes early on.  Main
>     one was adding baffles to the air vents facing back to reduce light
>     leaks.
> 
>     The lens tube revs only matter when you have a broken one needing to be
>     replaced or your are changing the glass out of an existing lens tube.
>     ETC doesn't keep old revisions in stock, so you have to purchase a
>     matching pair of the newest revision, and the unbroken half of the old
>     lens tube goes into the bin of misfit parts, in hopes that it will be
>     useful for a future broken other half of the same revision lens tube.
> 
>     trying to mate different revs of the left and right lens tube castings
>     is an exercise in futility.  they designed the mating lips of the two
>     castings so they only fit together properly with the same rev.   You
>     can
>     force them to go together, but now the lens tube is out of round,
>     leading to glass falling out when it's bumped, and it won't fit into
>     the
>     rest of the fixture easily.
> 
>     The lamp caps are the old 575 watt or below only, 575/750s, and the
>     dimmer doubler ones.   There are lots of the old 575 caps around that
>     people drilled out to allow 750 lamps to fit, but they need that extra
>     heat sink and light blocking casting to handle the heat long term. 
>     When
>     you don't have that extra heat sink, the heat messes up the dichroic
>     coating on the reflector, giving it a case of dandruff. (flakes falling
>     off)  At that point you have to replace the reflector, which is a bit
>     spendy.
> 
> 
>     Dale
> 
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> 
> -- 
> Jon Ares
> www.arescreative.com <http://www.arescreative.com>
> 
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