I did accidentally posted this elsewhere, so I'll have another go. I must get on these forums more often but always short of time: I'm just writing a blog post about this and thought I'd add my own thoughts. So far, in order to keep Leica rangefinder cameras alive, we figured out how to restore rangefinder prisms, utilising physical vapour deposition to do so. When I got back into the business, I didn't think vacuum chambers and magnetrons would be on my tool list! In order to solve the brightline mask issue, we had to find a way of reverse engineer these things and we did just that. The M6 concerns me. Let me explain.
The circuit comprises of three main parts. The flex which is the stuff you see everywhere in computers, other cameras, flexes that break in compact camera zoom lenses etc. There is a section of conventional PCB material that houses the shutter speed contacts and components and the piggy tail (meter switch). Then you have a hybrid circuit board. I'm old school. You were not allowed to swap parts unless really necessary, you had to fault find down to component level. Everywhere else, normal soldered SMD components are used. The hybrid board is ceramic with screen printed tracks and contacts, along with what look like screen printed resistors directly onto the substrate. Some components are covered with blobs of epoxy, either to protect or hide them.
This means work is very precarious and SMD components aren't soldered, they are attached using conductive epoxy. Sometimes we can fix them, sometimes we can't. My approach is this, re-design the whole thing and remanufacture them. I'm already working on this. I might also think about the TTL version too and include adjustment pots like the M6, avoiding the need to hook the camera up to a Leica computer just for adjustment.
