[email protected] wrote in message
...
On Thu, 3 May 2012 02:26:10 +0100, "Arfa Daily"
wrote:

These moving heads have the reflector as part of
the fixed optics. The lamp is 'bare' and fits into a ceramic holder that
is
then fixed in some way behind the reflector, such that the lamp pokes
through the centre hole in the reflector to a distance where the internal
quartz glass discharge tube sits at the focal point.

That's the idea I'd like to try. We have two Chauvet Q Spots that do
something
similar with a bright white LED, though I doubt the particular LED they
use
would be bright enough. It seems to be mounted directly to a heat sink if
I
remember right, and if it *has* to be mounted on a heat sink that would be
a big
problem. But if it could be mounted on an extending piece of metal even if
it
has to be perforated or whatever, it seems it could then be put through
the
reflector and positioned wherever it needs to be. It would take some
thought and
work to make such an adaptor, but then the fixture would be good to go
again
using a lot less power, creating a lot less heat and the resulting damage
from
heat, and there would be no need to buy bulbs again instead of every six
months
or so. Also fixtures wouldn't be shut down by problems with lamping on,
which is
the biggest problem we have with our fixtures. From what I understand, two
of
our electronic ballast Mac 500s are not worth fixing because the ballast
costs
$1300+, even though the rest of both fixtures seem to be in good
condition.

Something else. The Mac 101s kick ass with a nice solid beam in pretty
much all
colors. Do you know what wattage LEDs they are? Someone told me 3 watt,
but I
haven't been able to find where it says that specifically. Anyway, I would
like
to find some LED "par can" type fixtures that put out a similar beam, and
I've
seen 3 watt LED pars advertised but don't know if it would be the same or
not.
The idea is that if we can get some of those, we could strip our old
messed up
600s down pretty much to the frame and mount the LED pars in them to get
something similar to the 101s. They would be run as two different
fixtures, but
we'd only have to fool with pan and tilt on the 600s part... So do you
know of
any LED pars, the cheap type from China, that might do the job? Or what
specifically I should look for in an attempt to find them?


High power LEDs definitely need cooling. Sometimes, it's done through a
special PCB that has an internal metal layer, but 'proper' high power
examples require screwing down to decent sized metal heatsinks. Also, in
order to get best efficiency and life from the LEDs, they prefer to be pulse
driven, so that's some additional electronics that's required. I also don't
think that you would get much success trying to substitute a flat plane
light source like a LED, into optics that have been designed to work with a
short arc discharge lamp that emits light in pretty much every direction
except at the very ends. The eliptical reflector is designed to collect
light from this type of source, and focus it into a loose forward beam that
is then distance-focused by the multistage lens system at the front.

Presumably for that sort of money, the ballast is electronic ? If so, just
repair it and save yourself $1200. Most ballast faults that I've had, are
down to failed power semiconductors. No great shakes to find or replace.
Also, in contrast to most manufacturers of electronic equipment these days,
I've found lighting manufacturers to be quite helpful in terms of service
information. I'm not sure how Martin are in this regard, but it would be
worth an ask.

Arfa