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Cleaning old lamps


pmiller056

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I need to properly clean the optical parts of some Strand Prelude (500/650W) profile spots at our local community theatre. The light output from them is very poor, even with new lamps. When looking at the lenses when they are lit, they are clearly covered in accumulated crud. Any hints and tips would be appreciated. Do any of the lenses in these lamps have any optical coatings? Are the reflectors front or rear silvered? If so how do I clean them without damaging any coating/silvering?

 

Thanks

 

Peter

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I need to properly clean the optical parts of some Strand Prelude (500/650W) profile spots at our local community theatre. The light output from them is very poor, even with new lamps. When looking at the lenses when they are lit, they are clearly covered in accumulated crud. Any hints and tips would be appreciated. Do any of the lenses in these lamps have any optical coatings? Are the reflectors front or rear silvered? If so how do I clean them without damaging any coating/silvering?

 

Thanks

 

Peter

I don't think that there are any special coatings on the lenses and the reflectors have the reflective surface at the front. I tend to avoid more than a light dust on the reflectors but the lenses receive a much more thorough treatment since they can gather some very stubborn deposits. Once I have gained good access to the lenses (significant disassembly can be quicker in the long run than trying to clean 'through a porthole') I wash them in luke warm soapy water. Wash this off with clean water and then finish with a spray of isopropyl alcohol water (50:50 as in spectacles cleaner) and a polish with a micro fibre cloth. I then use the same cloth to remove any dust from the lamp. Re-assembly takes sufficient time to allow everything to be dry and alcohol free before testing.

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it's amazing how few amateur or school theatres clean their lenses - quite a few pro theatres as well!

 

you'll be shocked at how much dirt comes off.

a dab of HT grease on things like worm drive helps as well.

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Agreed - it makes a huge difference cleaning the lenses.

 

I find removing the front frame holder and sliding the entire lens carrier out is pretty quick and makes it much easier to get the lenses really clean. Preludes are pretty easy to strip and reassemble - easier than quartets.

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...and while you have them in pieces check obvious things: right lamp fitted (you would be amazed how often this is not the case) and lamp holder in good condition (no sign of arcing in particular). Check that the correct lenses are fitted and are the right way around (if they can focus to a sharp spot at both minimum and maximum beam sizes then this means they are OK).

 

I did a mega clean for a local amdram company some years ago and the difference in light output afterwards was amazing (including identifying one with the lens tube reversed so was just a light on the rig which did nothing useful!) At my little theatre we give our lanterns a gentle clean once a year - soft dry cloths on the reflectors and soft damp clothes on the lenses, then a visual check of everything else.

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http://www.poundland.co.uk/microfibre-cleaning-cloths-4-pack

 

microfibre cloths are the thing for cleaning lenses, reflectors and LCD screens, use one wet then one dry.

 

Vinegar makes a good surfactant, water is the solvent, vinegar makes it wetter. Washing up liquid can contain salt.

 

Isopropyl and water for more stubborn stains.

 

ETC reflectors and lenses are coated and possibly a bit more sensitive than Strand`s from back in the day

 

https://www.etcconnect.com/Support/Articles/How-To-Clean-Source-Four-Lenses-And-Reflectors.aspx

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