8mm Forum: Bell & Howell 642 Exciter Lamp

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Topic: Bell & Howell 642 Exciter Lamp

Paul Mason
Jedi Master Film Handler

Posts: 540
From: Aldershot, Hampshire, UK
Registered: Nov 2013

posted June 24, 2014 03:14 AM

Dear All,
I have recently bought a Bell & Howell 642 projector. All seems well but the exciter lamp is missing. The handbook says it needs a 6 volts 1 amp lamp and quotes a Bell & Howell part number I don't recognise. I have several spare G27 4V 0.75A lamps used in later Bell & Howells but no 6V version. Do I need a G5 lamp (this has the same P30s base)? Has anyone tried using the 4V lamp and how long do they last? All comments gratefully received.

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Paul.

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Maurice Leakey
Film God

Posts: 5895
From: Bristol. United Kingdom
Registered: Oct 2007

posted June 24, 2014 05:06 AM

Paul
The lamp you need is a G/40. (6 volt 1 amp.)
The G/27 you have is for Elfs and Elmos, the later B&H projectors used the G/29.

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Maurice

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Paul Mason
Jedi Master Film Handler

Posts: 540
From: Aldershot, Hampshire, UK
Registered: Nov 2013

posted June 24, 2014 06:17 AM

Maurice,
Many thanks for your definitive answer. I should have said I have G29s as these are horizontal filaments not G27s with vertical filaments. G5s are definitely wrong as these also have vertical filaments. A trap for the unwary.

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Paul.

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Dominique De Bast
Film God

Posts: 4486
From: Brussels, Belgium
Registered: Jun 2013

posted June 24, 2014 11:26 AM

I was trapped a few months ago. I was wondering why the bulb I put as a replacement was not working. Maurice gave me the answer by explaining some exciter lamps only differ by the position of the filmament. Thanks again, Maurice.

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Dominique

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Maurice Leakey
Film God

Posts: 5895
From: Bristol. United Kingdom
Registered: Oct 2007

posted June 24, 2014 02:57 PM

I have mentioned this a long time ago but I'll repeat it. A non-movie friend had acquired a Bell & Howell TQII which he wanted to sell on to me. When I had a chance to try it out the sound was so bad it was barely audible.

Obviously it needed some attention so I got the 1658 for £15, this was in 1994.

When I got the projector home I gave it a good check-over and discovered it was fitted with a G/27 exciter lamp. After replacing it with the correct G/29 it worked like a charm.

As Dominque said the lamps only difference is the position of their filament, the G/27 operates (Elf and Elmo) in a horizontal position, the G/29 for the Bell & Howells operates in a vertical position.

I still have the projector and over the last few years have spent £75 on routine maintenance. It's a useful projector as it also has magnetic playback capabilities.

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Maurice

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Paul Mason
Jedi Master Film Handler

Posts: 540
From: Aldershot, Hampshire, UK
Registered: Nov 2013

posted June 25, 2014 05:46 AM

I think the filament positions are the other way round
G/27 vertical, G/29 horizontal as can be seen in several Ebay listings.

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Paul.

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Maurice Leakey
Film God

Posts: 5895
From: Bristol. United Kingdom
Registered: Oct 2007

posted June 25, 2014 02:45 PM

Paul
You are right, but I was referring to the lamps' operating positions in the projectors, not the filament.
In each position the filaments of the two different lamps are, of course, horizontal.

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Maurice

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Paul Mason
Jedi Master Film Handler

Posts: 540
From: Aldershot, Hampshire, UK
Registered: Nov 2013

posted June 26, 2014 03:16 AM

Maurice,
Apologies for not reading your post properly. I am not familiar with the use of the G/27 lamps. I suppose it would be rather difficult to focus a vertical filament onto a horizontal slit.

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Paul.

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Paul Mason
Jedi Master Film Handler

Posts: 540
From: Aldershot, Hampshire, UK
Registered: Nov 2013

posted July 01, 2014 02:55 AM

I have now fitted a G/40 exciter lamp as suggested by Maurice. It seems to be physically identical to the G/29 except for a slightly longer filament. Incidentally, according to the 1960 Bell & Howell book by Edwyn Gilmour the 600 range up to the 640 require a G/29. Bell & Howell then changed this to the G/40 for the 641 onwards before reverting to the G/29 in 1969 for the TQ models!! [Confused]

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Paul.

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Maurice Leakey
Film God

Posts: 5895
From: Bristol. United Kingdom
Registered: Oct 2007

posted July 01, 2014 07:58 AM

The very first British made Bell & Howell, the Bell & Howell-Gaumont 601, used the G/19 or G/4. These were virtually the same as the G/29 but without the "skirt".

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Maurice

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