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Other Vintage Household Electrical or Electromechanical Items For discussions about other vintage (over 25 years old) electrical and electromechanical household items. See the sticky thread for details. |
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21st May 2022, 7:22 pm | #1 |
New Member
Join Date: May 2022
Location: Toulouse, France
Posts: 1
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Bell and Howell Filmosound 592 valve amp help.
Hello, I subscribed to ask if by any chance someone here would have the service manual of the Bell and Howell 642 16mm Projector.
https://ian-partridge.com/bh_642.html This has a tube amp has two row of tubes : upper row = EF86 - EF86 - EF86 lower row = EL84(6BQ5) - EZ81 - EL84 - EL84 - ECC83(12AX7) the downer row is the EF86 used probably as preamp for the mic input and/or the light cell (for optical sound) and the upper is the rest of it. Does someone have a schematic of this machine? I don't know if it works I don't want to fry anything if someone one day put the tubes back in the amp without watching where is what. It seems strange to see 3 EL84... |
21st May 2022, 9:39 pm | #2 |
Dekatron
Join Date: Feb 2007
Location: Lynton, N. Devon, UK.
Posts: 7,088
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Re: Bell and Howell Filmosound 592 valve amp help.
It's possible that one of the EL84's is used as a high frequency oscillator, to drive the sound exciter lamp. 50Hz is no good because the light will vary at 100Hz rate - it needs to be either DC or high frequency. And HF was often easier than having metal rectifiers and smoothing.
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22nd May 2022, 12:13 pm | #3 |
Heptode
Join Date: Dec 2020
Location: Swaffham, Norfolk, UK.
Posts: 587
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Re: Bell and Howell Filmosound 592 valve amp help.
Have you contacted Van-Eck video services? They may have what you are looking for and will provide a PDF for a small charge... (Search Van-eck.net).
Last edited by G.Castle; 22nd May 2022 at 12:15 pm. Reason: typo |
22nd May 2022, 4:50 pm | #4 |
Octode
Join Date: May 2009
Location: Stevenage, Herts. UK.
Posts: 1,518
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Re: Bell and Howell Filmosound 592 valve amp help.
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