Focus stuck Minolta MD 50mm f1.7

[Wade D]

I bought a nice SRT 201 for a very low price because of a non focusing lens. Minolta MD 50mm f1.7. The aperture works freely as it should but the focus ring will not budge. Granted, they are very inexpensive now but I'd like to see if this one will work. Should I try to disassemble it? If so, how does one do that? I have a set of jewelers screwdrivers and a spanner.
Thanks in advance,
Wade

[benjiboy]

If it was mine I'd buy another one that works and save myself a lot of trouble.

[RMD]

http://www.pbase.com/pganzel/disasse...xxum_50mm_lens

http://www.youtube.com/watch?v=u9sK-iDytms

[ic-racer]

Many times you can flush the helicoid without disassembly of the lens. I just freed up two hard-to-turn Zeiss lenses yesterday. I use a syringe and needle to get some Naptha to the helicoid, working from the back. Sometimes you have to remove some stuff to see. Last month I got a Yashica lens with sand in the helicoid. I was also able to flush that out with Naptha and not have to disassemble the lens.

Realize that most lenses have the helicoid and a threaded portion that spins. You need to get both the threaded portion and the helicoid stared in the correct grooves for it to work correctly when you put it back to gether. This can be difficult.

[John Koehrer]

Hi Wade,
I suspect the lens has been dropped and jammed the helical. If you can get it to rotate at all you may need something like a valve grinding compound to get enough clearance for it to loosen up.

If you're just curious, start at the back and remove stuff that's in the way. watch out for the ball bearing or spring that provides the detent action. When you pull the aperture ring there will be grooves that it rides along. take pitchers or commit it to memory or notes.there will be a spring or two but they're secure. they have loops on the ends and fit over small studs with grooves for the loops.

DON'T DO THE FOLLOWING. Until you're sure the helical is really jammed.
There are two guides for the helical that are screwed in from the back. they're on opposite sides of the lens and held in with two screws each That will allow the helical to unscrew.

FROM THE FRONT.........The decorator ring unscrews CCW. Grip it with the edge of a rubber plug(bathtub stopper?)
under that there are three screws holding the focusing ring on.

I don't remember now exactly but the diaphragm may be removed now. three screws? springs on the lever in the back?
If you're in need of some real training in patience, take the diaphragm assembly apart(snicker) won't take but a minute. Reassembly will take a bit longer. First one might be an hour or two, depends on how steady you are and whether you sneeze on the assembly when it's almost done. Note the direction the blades face when yu take it apart, It doesn't work with them in backwards.

[Wade D]

Thanks for the replies. I was most interested in getting the camera and wasn't too concerned about the lens. I have a nice 35mm f1.8 to put on it. Mostly I was curious as to the cause of the jam and if it could be a simple fix. Doesn't sound like it so with no further ado I will tear into it just out of curiosity. If I mess it up, no harm done.