Post by John Farrell on May 10, 2017 23:01:24 GMT -5
A few weeks ago, I bought 3 old Prakticas, 2 FX3s, and one even older - so old it isn't even called an FX.
Surprisingly, the FX3s both work reasonably well. The mirror on the older one, though, wasn't locking down when it was wound.
To get a closer look at the problem, I removed the front plate
and the lens mount. There were no shims under the mount.
This disclosed the offending mechanism - the odd shaped plate with the pin in the slot, you can see here:
The pin moves the plate forward, to release the mirror, when the shutter release is pressed. A spring then returns the plate ready to engage the mirror on the next wind. The plate was sticking forward, and not catching the mirror.
I tried cleaning and lubricating what I could see, but it made no difference. I needed to get at the outside of the mirror box.
The outside of the mirror box is accessed through the film takeup chamber. Getting into it means removing the film gate plate - it is held in by 6 screws. Under the plate is where you will find the shims that are used to adjust focus. The camera top plate also has to be removed, so you can later take out the film sprocket assembly - the rewind clutch release pin sticks though the top plate. Six screws secure the top, and you will need a special tool to undo the speed selector knob - I made one out of an old screwdriver, years ago. The thread is a left hand thread, and unscrews clockwise.
Surprisingly, the FX3s both work reasonably well. The mirror on the older one, though, wasn't locking down when it was wound.
To get a closer look at the problem, I removed the front plate
and the lens mount. There were no shims under the mount.
This disclosed the offending mechanism - the odd shaped plate with the pin in the slot, you can see here:
The pin moves the plate forward, to release the mirror, when the shutter release is pressed. A spring then returns the plate ready to engage the mirror on the next wind. The plate was sticking forward, and not catching the mirror.
I tried cleaning and lubricating what I could see, but it made no difference. I needed to get at the outside of the mirror box.
The outside of the mirror box is accessed through the film takeup chamber. Getting into it means removing the film gate plate - it is held in by 6 screws. Under the plate is where you will find the shims that are used to adjust focus. The camera top plate also has to be removed, so you can later take out the film sprocket assembly - the rewind clutch release pin sticks though the top plate. Six screws secure the top, and you will need a special tool to undo the speed selector knob - I made one out of an old screwdriver, years ago. The thread is a left hand thread, and unscrews clockwise.
