16-12-2021, 10:15 PM
As I could not work out which forum this post belongs in, could the mods relocate this if necessary please. There seems not to be a heading for film, not surprising!
Bell & Howell 626 16mm cine projector.
Ex education dept so its been hacked about a lot by some very bad repairers.
I was not interested in the mechanism, there were no reel arms, lamp or belt drives with it, bought as scrap.
But I thought the amplifier may be interesting as they are a bit unusual.
First odd thing is that these are AC/DC machines yet there is a transformer and a dropper resistance! All the voltage and AC or DC selectors have been removed long ago so its a bit of a detective job.
I have read that there have been guitar players electrocuted trying to use these amps, hopefully I have more understanding of the risks and how to mitigate them.
I can't find a circuit diagram, I'm not surprised as this is a bit of an oddball, dates from the mid 1950s.
Glass photocell feeds into an EF86 for the detection of the sound track. ECC83 amp/phase splitter into four UL84 valves. I don't yet know how these are arranged in push-pull. Worth what I paid for it if any of the valves are OK.
Strange construction of two pcbs, component sides facing one another, makes access very difficult. Valves sticking up around some green electrolytic cans.
Any input from someone who has played with one of these? Any circuit diagrams?
Sam.
Bell & Howell 626 16mm cine projector.
Ex education dept so its been hacked about a lot by some very bad repairers.
I was not interested in the mechanism, there were no reel arms, lamp or belt drives with it, bought as scrap.
But I thought the amplifier may be interesting as they are a bit unusual.
First odd thing is that these are AC/DC machines yet there is a transformer and a dropper resistance! All the voltage and AC or DC selectors have been removed long ago so its a bit of a detective job.
I have read that there have been guitar players electrocuted trying to use these amps, hopefully I have more understanding of the risks and how to mitigate them.
I can't find a circuit diagram, I'm not surprised as this is a bit of an oddball, dates from the mid 1950s.
Glass photocell feeds into an EF86 for the detection of the sound track. ECC83 amp/phase splitter into four UL84 valves. I don't yet know how these are arranged in push-pull. Worth what I paid for it if any of the valves are OK.
Strange construction of two pcbs, component sides facing one another, makes access very difficult. Valves sticking up around some green electrolytic cans.
Any input from someone who has played with one of these? Any circuit diagrams?
Sam.
Boater Sam.
