Durst CLS450 broken part

Hi all, thanks for letting me join the forum and hope this post is ok. I have a durst CLS450 head with a couple issues and looking for advice on if I can repair forget it repaired by someone the UK. I've been using it to a basic level okay even with this issue and only spotted it recently when I went to replace the bulb and got a torch inside. There's a broken piece of square glass below the colour filters as visible the pix. I've tried and struggling to remove there metal top to get to the part. I guess my main queries I'd be super grateful for any advice, specifically:
what is the part and what does it do?!
Is it vital for basic print quality? - (I haven't see any corresponding imprefections on points so far but I'm not very experienced printing! There seems to be a diffuser below it that masks the problem somewhat.)
How do I get to the part (I am struggling too get the top off - do I need to remove the colour filter controls to get the metallic off?)
Is it a part I could realistically replace myself, or is there a repair person/place in the UK?
One other question if I may, I print b/w & only use the colour filters for contrast, but the colour controls seem to move a different colour piece of glass (although the correct ciorresponding colour dial on the front). The blue control moves blue dial but the red glass, the red moves red dial but the yellow glass and the yellow moves the yellow dial blue glass! this seems weird to me ..have colour filters been put on the wrong way?? Does it matter?
The head's case is a bit gaffered together and missing a few screws so I know it's been got at but and it does seem function to a level but I'm hoping I can get it fixed up better.
Any advice VERY gratefully received! Thank you!

Welcome to Photrio @aderollei !

I find the picture a little hard to interpret, but I suspect the piece of glass you're referring to is a heat filter that protects parts of the head (i.e. the diffusor and everything downstream from it) from the heat of the bulb.

You could try approaching one of the sellers on eBay dealing in Durst stuff and see if they perhaps have a replacement to sell to you. Such parts are generally sold at a premium.

aderollei said:

Is it a part I could realistically replace myself

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On these heads, in principle almost anything can be DIY-ed; it's relatively straightforward mechanics.

aderollei said:

the colour controls seem to move a different colour piece of glass

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Dichroic filters look differently depending on the angle you look at them. The cyan (not blue) filter reflects red light and transmits the rest, that's why it's cyan (cyan being the inverse of red). Likewise, the yellow filter looks blue if you let light reflect off of it, and the magenta filter looks green. This is nicely visible in your photo.

koraks said:

Welcome to Photrio @aderollei !

I find the picture a little hard to interpret, but I suspect the piece of glass you're referring to is a heat filter that protects parts of the head (i.e. the diffusor and everything downstream from it) from the heat of the bulb.

You could try approaching one of the sellers on eBay dealing in Durst stuff and see if they perhaps have a replacement to sell to you. Such parts are generally sold at a premium.



On these heads, in principle almost anything can be DIY-ed; it's relatively straightforward mechanics.



Dichroic filters look differently depending on the angle you look at them. The cyan (not blue) filter reflects red light and transmits the rest, that's why it's cyan (cyan being the inverse of red). Likewise, the yellow filter looks blue if you let light reflect off of it, and the magenta filter looks green. This is nicely visible in your photo.

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Thanks very much @koraks that makes total sense and very much appreciate the reply/ thoughts. it explains my filter colour confusion, and also makes sense that the broken glass is a heat filter part as it is first in line beneath the bulb so would perform that duty well. I will explore replacement as you suggest. Many thanks appreciate the help as I was a bit lost. thanks!

Things that one might find broken in a CLS 450 head would be the UV filtrer, Heat Absorbing Filter, Mirror and Diffuser.

ic-racer said:

Things that one might find broken in a CLS 450 head would be the UV filtrer, Heat Absorbing Filter, Mirror and Diffuser.
View attachment 366887

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thanks very much @ic-racer that's a helpful parts diagram...I'm going to take a closer look .. I think it's the top one nearest the bulb as I can reach in to the broken hole from the top/bulb so I think probs heat filter-probs- if it was mirror then i'd guess the images wouldn't print out ok and they're not really affected much by the broken part. thanks for the help

aderollei said:

so I think probs heat filter-probs- if it was mirror

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I agree with your line of reasoning. The heat filter is also the one likely to be closest to the bulb. Logically it should also be between the bulb and the dichroic filters, to protect the latter from heat damage in the long run. But that's speculative on my part.

koraks said:

I agree with your line of reasoning. The heat filter is also the one likely to be closest to the bulb. Logically it should also be between the bulb and the dichroic filters, to protect the latter from heat damage in the long run. But that's speculative on my part.

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cool thanks @koraks