Olympus-OM
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[OM] Scratch Build

Subject: [OM] Scratch Build
From: HI100@xxxxxxx
Date: Sat, 12 Oct 2002 03:15:50 EDT
Cc: Doggre@xxxxxxx
Rich wrote: 
>>
I know the circuit boards would limit the modifications to a great degree, 
but what about the mechanical parts?  What fits across different models?  
What doesn't?

A "bullet-proof" OM-2S with pawl & gear wind mechanism and battery-saving red 
"flash ready" LED would be a beautiful thing.  Any other mods that might be 
made?  Other models?
<<

Rich,
        as far as the cct board for the 2S this would be a major software and 
hardware undertaking to duplicate, but the 2N or 2 would be a much more 
modest electronic effort.  There are now low voltage commodity CMOS opamps 
and comparators that could easily be used to simplify the circuit a 
little,cut power consumption and improve performance. Board leakage control 
without using a ceramic "board" like the OM would be a challenge but not 
insurmountable. The relay curtain release would be very difficult to 
substitute but these probably don't fail very often, apart from getting 
sticky with oil? The blue enhanced silicon photocells could be replaced since 
cells of about the right area are common. Finding one with a suitable tiny 
lens might be an issue and a small filter to cut infrared might have to be 
added. Spare cells for the Calcu-flash meter series from Quantum might be 
close to ideal replacements since they include a suitable filter and molded 
lens. Small CdS cells for the manual meter are available but the component 
values for the cct resistors would need changing, since it is very unlikely 
the cell characteristics would match the OM cells exactly. The meter movement 
would have to be salvaged. With newer surface components, the 2N auxiliary 
board functionality could even be duplicated on a small pc board. The battery 
test LED cct could be duplicated or better yet simplified with newer parts. 
The flash SCR and diode isolator should be easy to find or substitute. The 
switches might be tougher to repair if the contacts are worn?

Tim Hughes
TimHughes@xxxxxxxx
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