Reviving an AO 735 illuminator

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Radazz
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Reviving an AO 735 illuminator

#1 Post by Radazz » Fri Oct 19, 2018 4:31 pm

Since more than half my collection consists of microscopes with mirror illumination, I decided I wanted to find a laboratory illuminator with an iris. The readily available illuminators that fit were both AO Spenser’s. The 370 or the 735.
I figured the device was going to stay at the back of my observing table, and being an aesthete, I went with the 735 because IMHO the 370 looks Ike a railroad lantern, and the 735 looks like something from Dr. Zircov’s laboratory.

The one I got was missing the condenser lense and the filter rack.

Image

First test the device projected an image of the filament. Then after 15 minutes the lamp rung down the curtain and joined the choir invisible.
I looked on line for a replacement lamp and found one only for $40 USD.
So I changed out the bayonet socket with a candelbra socket, giving myself a wide variety of readily available lamps to choose from. I selected a 60w clear lamp and carefully lined the filament up with the center of the parabolic reflector to get the most light, and it worked fine but still projected the filament.

Image
I placed 2 layers of wax paper over the front of the condenser, which doesn’t get too hot for it, and the filament image disappeared!

Image
Next I found a Cokin style filter set and rack, and adapted it to fit on the front of the illuminator

Image

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With a neutral density filter I get nice even bright light.
The rack came with two dozen filters in solid and gradient colors with some ND filters as well.
Now I’m narrowing them down to the 4 or 5 that I will probably us with the microscope.
The set came with a second rack that I can use with my camera as well.
These old illuminators usually get HOT, but I was surprised how efficiently this design handles the cooling. I could place my hand on the unit after 30 min. of operation and, while uncomfortably warm, I didn’t burn myself.

Enjoy, Radazz
Arnold, Missouri
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rnabholz
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Re: Reviving an AO 735 illuminator

#2 Post by rnabholz » Fri Oct 19, 2018 5:16 pm

Nice work getting it up and running again. They are a cool looking device.

If you search for "BMY 100w bulb" you should be able to find a replacement for the original bulb much cheaper than $40. Here's one:

https://www.amazon.com/Ushio-BC6069-100 ... B000YL1PEA

Have fun with it, I do.
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Hobbyst46
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Re: Reviving an AO 735 illuminator

#3 Post by Hobbyst46 » Fri Oct 19, 2018 6:44 pm

Radazz wrote:These old illuminators usually get HOT, but I was surprised how efficiently this design handles the cooling. I could place my hand on the unit after 30 min. of operation and, while uncomfortably warm, I didn’t burn myself.
That means, that the temperature of the unit was less than about 47-50C.
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo

einman
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Re: Reviving an AO 735 illuminator

#4 Post by einman » Fri Oct 19, 2018 7:05 pm

Those older lamps were beautiful. I have 2 myself.

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Radazz
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Re: Reviving an AO 735 illuminator

#5 Post by Radazz » Fri Oct 19, 2018 7:36 pm

rnabholz wrote:Nice work getting it up and running again. They are a cool looking device.

If you search for "BMY 100w bulb" you should be able to find a replacement for the original bulb much cheaper than $40. Here's one:

https://www.amazon.com/Ushio-BC6069-100 ... B000YL1PEA

Have fun with it, I do.
Well, I’m committed to the new socket now I can get a new lamp at the grocery store if I need one.
Arnold, Missouri
Olympus IX70
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MicroBob
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Re: Reviving an AO 735 illuminator

#6 Post by MicroBob » Fri Oct 19, 2018 8:38 pm

Hi Radazz,
nice new light source!
I saw here in the forum that somebody has a nice old Köhler-lamp on his desk for use with his old microscopes and liked the idea very much.
Your AO 735 is a beautiful piece of cast metal in a nice paint.

Once I converted a Projectina forensic microcope lamp to LED. It was quite difficult to find a way to get the heat away from the strong LED. The microscope was intended for a permanent display in a museum display cabinet and would have run 16 hours a day so the cooling would have to be good.

Bob

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rnabholz
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Re: Reviving an AO 735 illuminator

#7 Post by rnabholz » Fri Oct 19, 2018 10:57 pm

Radazz wrote:
Well, I’m committed to the new socket now I can get a new lamp at the grocery store if I need one.
Of course, I offered the info in case someone else might benefit.

You came up with a nice work around and have it up and running and that is the main thing. My comment was not meant to diminish that. Well done.

Rod

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Radazz
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Re: Reviving an AO 735 illuminator

#8 Post by Radazz » Sat Oct 20, 2018 12:20 am

Perfectly alright :)
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KurtM
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Re: Reviving an AO 735 illuminator

#9 Post by KurtM » Sat Oct 20, 2018 12:22 am

Ah yes, the old 735 is a perfectly lovely lamp! 8-)
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Radazz
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Re: Reviving an AO 735 illuminator

#10 Post by Radazz » Sat Oct 20, 2018 5:33 pm

And the Spencer model 13 MLH is a thing of beauty as well.
Arnold, Missouri
Olympus IX70
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