Yashica M shutter speed issue

[jenniferkshields]

Kia ora!

First post here! I just picked up a Yashica M - which is a Minister with an updated lens - and it’s got this funny shutter issue! It fires fine on bulb - the blades open as expected - but on all other speeds, it appears to fire at 1/500s - or at least very, very fast.

I’m having trouble finding any repair manuals for the early model Ministers, and would love some tips on where to start! I intend to give the blades a clean, and if that doesn’t fix it, look into the speed escapement. I’ve seen a couple of conflicting suggestions - both that I should disassemble from the very front of the lens, and that I should hold the focus ring firm and disassemble from there.

Does anyone have experience disassembling these that could give me a few pointers? Thanks in advance!

 

[shutterfinger]

This instruction manual https://www.cameramanuals.org/yashica_pdf/yashica_35_m.pdf says the M uses a Copal shutter.
There are Copal service manuals in the Leaf Shutters and Mamiya sections of https://learncamerarepair.com/productlist.php?category=2
If that is a front focusing lens then it will likely have multiple start threads with a stop screw at the extremes. Marking and installing the lens at the correct start point is critical for correct focus. The instructions for removing from the front of the lens/shutter is correct. The delay timer is stuck or very sluggish in operation. If the blades or controller were at fault B would not work. Remove the delay timer mechanism to clean it. The lens mount will need to be removed from the front of the body by lifting the leatherette, removing the mount screws, disconnecting the release mechanism from the body and disconnecting the rangefinder which may require calibrating on reassembly. I recommend avoiding removing the lens/shutter mounting if possible.
While I have not serviced one of these camera I have serviced Copal, Compur, Graphex, Supermatic, and Ilex shutters.