8mm Forum: Bolex M8

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Posted by Norman Peters (Member # 3993) on October 24, 2013, 12:25 AM:

Hi all - I have just bought a late model Bolex M8R (in Australia) with the stroboscope. Obviously in common with all M8s, it has a 500 watt lamp, and a dirty great wire wound resistor inside as teh lamp is a 110V device, and our power grid is 240V.

Both get incedibly hot, and a stream of hot air is blown out when the lamp is lit and teh projector is running. After the projector is stopped, I would imagine the residual heat in the internals must be intense.

My question - do you need to run it with the lamp off for a while to cool it down, blowing hot air out until it cools somewhat, or is it safe just to switch it off and let it stew?

Also, has anyone successfully replaced the 500 watt circutry with a modern halogen unit, or perhaps a spaceman bulb to circumvent the heat issue?

Many thanks, Norm

Posted by Dominique De Bast (Member # 3798) on October 24, 2013, 12:38 AM:

I would higly recommend you to run the fan several minutes after you switched the lamp off in a first time and to check the overheating of the electric wire you're reporting as soon as possible to avoid any danger and keep you among us.

Posted by Bryan Chernick (Member # 1998) on October 24, 2013, 10:13 PM:

I agree with Dominique, I run mine for a few minutes to cool the bulb when I'm done. I let the fan run wile I'm breaking down my screen and putting stuff away. Don't move the projector when it's still hot, that can damage the bulb. The heat can also damage wires and other electronic components.

Posted by Norman Peters (Member # 3993) on October 25, 2013, 03:14 PM:

OK and thanks, I will heed your good advice.
Norm

Posted by Steve Klare (Member # 12) on October 26, 2013, 03:15 PM:

If you could find a 240V equivalent bulb, you could bypass the wirewound resistor and cut the power inside the machine in half.

I'm on the fence with the issue of running the fan after the machine is turned off. A lot of the damage that temperature does is the mechanical stress that comes when something changes temperature very quickly and different materials expand or contract at different rates. Running the fans while the bulb is cooling means the bulb cools off much faster. By the same token what else are those hot parts cooking in there without the benefit of cooling air protecting them? (Listen to your heart!)

Dad always ran his fan after he turned his projection lamp off. Then again Dad had a habit of shifting into "Drive" while the car was still rolling backwards: even when I was 10 years old this made me wince!

Posted by Norman Peters (Member # 3993) on October 26, 2013, 05:35 PM:

Does anyone have any schematics of the electric circuit in the Bolex M8R they might pass on to me? From there I can probably work out what to do in regards to a lamp transplant.

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