Lamp orientation

[sunray]

Against several lots of advice we have just purchased 5 'Microspot 308 Fresnels' from ebay and possibly paid too much at £85. They are just as described: working and very dusty.

 

This brings me to the questions:

The frame holders on 4 are positioned so the lamp would be cap up.

From the dust it can be seen these have been used at a steep angle but 3 have been cap down 2 cap up.

The bulbs are currently 500W Osram M40's

 

Are these fussy which way up the should be? A very quick google search has so far been fruitless.

[timsabre]

Philips say their M40 can be used in any orientation. Not sure if this goes for other brands

 

"Very high light output (14500 lumens) from a compact source

Enables use at higher temperatures in any burning position

 

Two distinctive features make this lamp ideal for use in theater luminaires where long life is essential. Firstly, the filament is especially designed for extended lifetime. Secondly the highly innovative P3 technology, developed by Philips, allows the pinch to better withstand extreme heat conditions which extends the average lamp lifetime, ensures consistent high-quality light output over time, and results in fewer early failures and fewer maintenance man hour costs."

[sunray]

Thanks Tim, I'd been trying to look at Osram [as fitted] I know it's silly but I'll assume that applies to the style of lamp, especially as there isn't any obvious sign of suffering other than the crispy mains cable.

[timsabre]

Thanks Tim, I'd been trying to look at Osram [as fitted] I know it's silly but I'll assume that applies to the style of lamp, especially as there isn't any obvious sign of suffering other than the crispy mains cable.

 

Yes I suppose that's the other concern. If the internal wiring is going to get cooked by being used upside down then that isn't a good result. Couldn't you turn the fronts round to make them all lamp-base-down?

[Gerry]

[... Couldn't you turn the fronts round to make them all lamp-base-down?

Unless they have changed the design of them the colour frame runners are screwed to the front, so just turn them around. The colour runners where an optional extra.

I bought 4 when they first came out, they give out quite a lot of light including from the front.

They are also very hot in use as the case is just made of sheet steel without any significant means of keeping the case cool.

Cheers

Gerry

[sunray]

Brilliant info thanks.

Yes they are just screwed on, in fact they are all completely stripped down for cleaning/drying and I wanted to check before I re-assembled as so many of them were upside down.

I wondered how much light leaks and how hot these get as they are basic, there is no sign of overheating so I guess there is enough light leaking to be OK :)

[timsabre]

... they give out quite a lot of light including from the front.

Haha good description

[xllx]

I had the joy of focussing some of these when I helped out at a local AmDram show. They do get hot, I got a lovely burn on the inside of my forearm :-)

 

Personally if you are stripping them down. I would, use them lamp base down and adjust the colour runners to suit. I am pretty sure the M40 can be used base up, but I would be concerned about the wiring and would always prefer that to be below the lamp.

[sunray]

I had the joy of focussing some of these when I helped out at a local AmDram show. They do get hot, I got a lovely burn on the inside of my forearm :-)Personally if you are stripping them down. I would, use them lamp base down and adjust the colour runners to suit. I am pretty sure the M40 can be used base up, but I would be concerned about the wiring and would always prefer that to be below the lamp.

I've always preferred cap down but some lamps are designed for cap up and with the 'random' format of these 5 fittings I thought I'd check before it all goes back together. The wire above the bulbs has gone hard so this is the deciding factor.

My concern now is the amount of light leakage, there are a lot of big holes.

[sguy42]

I had the joy of focussing some of these when I helped out at a local AmDram show. They do get hot, I got a lovely burn on the inside of my forearm :-)Personally if you are stripping them down. I would, use them lamp base down and adjust the colour runners to suit. I am pretty sure the M40 can be used base up, but I would be concerned about the wiring and would always prefer that to be below the lamp.

I've always preferred cap down but some lamps are designed for cap up and with the 'random' format of these 5 fittings I thought I'd check before it all goes back together. The wire above the bulbs has gone hard so this is the deciding factor.

My concern now is the amount of light leakage, there are a lot of big holes.

 

I'm assuming they've all the got the reflectors?

 

I've seen a few where they are missing,in that case the leakage is astounding (& in my view would make them unusable).

 

Spares would probably be like rocking horse poo to find especially after nstage bought Lancelyn a couple of years ago.

[sunray]

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I had the joy of focussing some of these when I helped out at a local AmDram show. They do get hot, I got a lovely burn on the inside of my forearm :-)Personally if you are stripping them down. I would, use them lamp base down and adjust the colour runners to suit. I am pretty sure the M40 can be used base up, but I would be concerned about the wiring and would always prefer that to be below the lamp.

I've always preferred cap down but some lamps are designed for cap up and with the 'random' format of these 5 fittings I thought I'd check before it all goes back together. The wire above the bulbs has gone hard so this is the deciding factor.My concern now is the amount of light leakage, there are a lot of big holes.

I'm assuming they've all the got the reflectors?I've seen a few where they are missing,in that case the leakage is astounding (& in my view would make them unusable).Spares would probably be like rocking horse poo to find especially after nstage bought Lancelyn a couple of years ago.

 

Funny you mention reflectors, they are all very lose especially the cap up pair, I intend replacing the pop rivets and may add more if I can get past the round bulge.

Other than bulbs I don't think I'll be spending any money on spares as these are a bit basic and cheap construction, I have only got them to add a bit more operability to a local AmDram who currently have 4 fresnels on stage and FOH have 4 profiles & 4 slimline LED pars. I have a hunch the ceiling will be well lit with them and would look at other products to spend money on.

[richardash1981]

Having built a lot of these for Lancelyn, the colour holder was supposed to go on so the holder was at the bottom and the lamp base down. I suspect the mains cable gland also wouldn't like the other way up.

 

Whilst you have them apart check the earthing of both the lamp tray and the main body, this had to be added as a design change over the life of the product. The earthing was bare braid with bare crimp eyes, presumably because insulation would have melted!

 

I don't remember the reflector being a problem to replace once you had the lamp tray out, took the plug off and removed the slider lock knob, so that the sliding bit with the lamp on detached. Reflectors used to be a bulk item but I don't know where they came from. Beware they were metallised surface so don't use abrasive on them!

[sunray]

Having built a lot of these for Lancelyn, the colour holder was supposed to go on so the holder was at the bottom and the lamp base down. I suspect the mains cable gland also wouldn't like the other way up.Whilst you have them apart check the earthing of both the lamp tray and the main body, this had to be added as a design change over the life of the product. The earthing was bare braid with bare crimp eyes, presumably because insulation would have melted!  I don't remember the reflector being a problem to replace once you had the lamp tray out, took the plug off and removed the slider lock knob, so that the sliding bit with the lamp on detached. Reflectors used to be a bulk item but I don't know where they came from. Beware they were metallised surface so don't use abrasive on them!

Thanks for this Richard.

I must admit there were several surprises when I stripped them down and studied them.

I wondered about earthing as the outer case is not bonded, they have all passed electrical PAT when the lock nut is tightened but the moment it is slackened [whilst focusing] the outer case loses its protection.

The colour holders were in random positions and some of the fittings had been running base up, as demonstrated by the dust patterns and brittle cable, I have shortened the cable by removing the heat damaged end but the glands have survived very well.

The reflectors are in good condition [after washing with water and a touch of fairy], in fact the fittings are all in quite good condition as I suspect they were installed and left untouched until their removal. I have drilled out the slack pop rivets and replaced them and the reflectors are now firmly secured, I suspect the heat softened them and I will keep an eye on them and replace with something else if they get lose again.

The only issue now [other than earth strap] is one lampholder is faulty and I really can't make up my mind if it's worth spending any money to replace.

[richardash1981]

I must admit there were several surprises when I stripped them down and studied them.

I wondered about earthing as the outer case is not bonded, they have all passed electrical PAT when the lock nut is tightened but the moment it is slackened [whilst focusing] the outer case loses its protection.

They must be older units then. By ~1999 when I was there the three-way earth bond lead I described was employed to provide an earth path to the main outer case, the lamp door and the sliding lamp base at all times. This lead with a set of hardware had been sold a a field upgrade kit previously - there were still some around but I never made or fitted one so not sure of the details.