8mm Forum: Bell & Howell ext speaker problem

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Topic: Bell & Howell ext speaker problem

Jason Moffatt
Expert Film Handler

Posts: 104
From: Denham, Buckinghamshire, UK
Registered: Aug 2014

posted September 29, 2019 12:31 PM

I have just picked up my first bell & howell 16mm projector (a 1695) it seems to work ok but the extension speaker that comes with it seems to be dead, no sound at all.Ive tried another speaker in the extension socket on the projector and it works ok so that rules out a problem with the projector itself.The speaker and wire connections all look ok, no loose wires so what else could be stopping it from working ?.

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Maurice Leakey
Film God

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

posted September 29, 2019 02:48 PM

Jason
You use the words "extension speaker" as in the singular. The proper side cover should have two 16ohm speakers in it, wired in parallel to give 8ohms impedance.
If you have a meter that registers ohms, take a reading across the terminals of the speaker plug to see if there is continuity. Or, perhaps, it's not a proper Bell & Howell speaker unit?

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Maurice

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Jason Moffatt
Expert Film Handler

Posts: 104
From: Denham, Buckinghamshire, UK
Registered: Aug 2014

posted September 29, 2019 06:32 PM

Hi maurice, yes it’s the double speakers that are in the front removable cover.The built in speaker in the projector itself works ok but is not very clear.

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Maurice Leakey
Film God

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

posted September 30, 2019 02:28 AM

Jason

Look in the speaker case and you will see a socket for another speaker to be added as a further extension.

I suggest you plug the speaker lead into the projector, then, connect the earlier speaker which you mentored into this socket.
If it works, the wiring is probably OK to that socket.

If it does work, pull back the speaker cloths and check all connections, there may be a dry joint somewhere, if so, it's a job for your soldering iron!

You said the sound is not very clear, this may be dirty optics. Remove the exciter lamp cover and use a blower brush. Pay particular attention to a gentle blow behind the sound drum, this is where the solar cell is situated.

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Maurice

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Jason Moffatt
Expert Film Handler

Posts: 104
From: Denham, Buckinghamshire, UK
Registered: Aug 2014

posted October 02, 2019 03:10 AM

Ok, the low sound was due to the spring for the two sound drum tension rollers needing freeing, the sound is much better now.The two speakers in the side cover are still dead though, i plugged a second extension speaker into the socket which is inside the speaker cover and that second speaker worked but the original speakers do not.I have opened the black cloth covers around each one and had a close look at the wiring and all looks ok so i’m puzzled as to what it can be, what else can go wrong with them ?.

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Maurice Leakey
Film God

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

posted October 02, 2019 05:37 AM

If the wiring to the speakers is OK then it would seem that a previous owner has connected them to a high powered amplifier and severely damaged them in some way.

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Maurice

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Jason Moffatt
Expert Film Handler

Posts: 104
From: Denham, Buckinghamshire, UK
Registered: Aug 2014

posted October 03, 2019 06:54 AM

Thanks for the answer maurice, yes I've checked the wiring very carefully with a magnifying glass and there are no problems so you maybe right.There should be plenty of these about from machines with broken worm gears so it shouldn't be too hard to locate another one.

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Barry Fritz
Phenomenal Film Handler

Posts: 1061
From: Burnsville, MN, USA
Registered: Dec 2009

posted October 04, 2019 02:47 PM

Take a 9v battery and wire it so you have a lead from each terminal on the battery. Touch them to the speaker terminals. If you get a thump sound the speaker is ok. If not, the speaker is bad.. i’ve Never had a bad speaker, let alone two of them.

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Maurice Leakey
Film God

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

posted October 05, 2019 03:25 AM

An excellent tip from Barry.
But don't forget that the two speakers are wired in parallel, so if you do get a "thumping noise" make sure that both speakers are OK by listening very closely by each one.

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Maurice

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Jason Moffatt
Expert Film Handler

Posts: 104
From: Denham, Buckinghamshire, UK
Registered: Aug 2014

posted October 06, 2019 09:45 AM

Ok, i just tried that with the 9v battery and one speaker sounded but the other one nothing.

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Maurice Leakey
Film God

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

posted October 06, 2019 11:31 AM

If one speaker "thumps" and the other does not I suspect dry joints could be the problem. With a soldering iron carefully remove all speaker connections. Check each speaker individually with the battery.

Before you do this take photographs of the wiring to ensure you can re-solder the connections paying particular attention to the phasing. If a camera is not to hand make some drawings and particularly note the colour of the wires.

I've got many Bell & Howells, and like Barry, have never had "duff" speakers.

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Maurice

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