The same manual in Russian: ???????? FA50 - ?????? ?????-?????
Being unable to find a manual on the disassembly of these popular lenses, I had to find the method by trial and error. By the way, my experience can be useful for the community
The lens described is the FA50/1.7, FA50/1.4 must be identical, or very similar.
Of course, you perform the actions described below on your own risk
It is recommended to have a set of quality screwdrivers.
0. Infinity focus adjustment. If you just want to adjust infinity focus (like me), you don't need to disassemble the lens! I found this out after disassembly, as always
0a. Set the focus to the MFD, so that the moving lens housing is all the way out. There are three screws around this moving part (one of them shown with an arrow), unscrew them.
Take the decorative lens housing off.
0b. Set the focus to infinity. There are three screws inside the focusing ring that are holding it,shown by arrows on the picture below. Loosen them.
Be attentive: the screws in the deep, closer ones hold the front lens group, don't touch them!
0c. Hold one of the screws with tweezers or something similar and turn the inner ring counter clockwise. When the infinity focus is obtained (check on the camera), carefully set the outer focusing ring on the infinity mark (to the limit) and fasten the screws.
0d. Install the decorative lens housing back.
Lens disassembly.
1. Unscrew the five screws shown by arrows and remove the bayonet mount. Hold it while removing, because there are spring loaded contacts inside. In my case they did not actually jump out, but who knows...
2. Here are the contacts and springs, don't lose them.
3. Remove the aperture ring, A-position lock button will fall out of it.
4. Remove the round part that transfers the set aperture stop to the aperture blades and camera lever.
5. Remove the plastic contact group housing, it is held by one screw.
6. Remove the screws, shown by arrows.