This one has me stumped

[colyn]

Last weekend I picked up a couple of Leicas. The IIIc and IIIf. The IIIf needs service as was expected. The IIIc works fine at all shutter speeds including the slow speeds except for B. The shutter opens as it should without sluggishness but will not close when the button is released. I then serviced this camera but the B continues to remain non-working.

Any ideas about what could be the cause??

 

[Vickko]

Hmmm. I wonder if the spring the pushes up from the bottom isn't as strong as it should be. Or when the shutter button is released, it isn't traveling up high enough.

 

[Mudman]

Are you sure you're not setting it to time by accident? I know with T mode you have to move the front speed selector

 

[Brian Legge]

If the slow speed selection works like it does on the earlier canon rangefinders, it may need an adjustment of screw in the middle of the slow speed adjustment knob.

At least on the canons, the slow speed adjustment knob pushes down a lever which controls the shutter speed. The screw in the middle of the knob controls how far down it is pushed. If it isn't pushing the lever far enough (or if its too far - not sure which direction it would need to be adjusted), B may be behaving like T. It would also mean that the fastest speed on the slow speed dial may be running slightly slow.

 

[colyn]

Are you sure you're not setting it to time by accident? I know with T mode you have to move the front speed selector

If you are referring to the "T" setting that is controlled by the slow speed dial. The "B" is on the main dial...

 

[colyn]

If the slow speed selection works like it does on the earlier canon rangefinders, it may need an adjustment of screw in the middle of the slow speed adjustment knob.

This adjustment only affects the speeds from 20th down to 1 second and T. It has nothing to do with the B which is on the main dial.

At least on the canons, the slow speed adjustment knob pushes down a lever which controls the shutter speed. The screw in the middle of the knob controls how far down it is pushed. If it isn't pushing the lever far enough (or if its too far - not sure which direction it would need to be adjusted), B may be behaving like T. It would also mean that the fastest speed on the slow speed dial may be running slightly slow.

All shutter speeds have been checked and are within tolarance..

 

[colyn]

Hmmm. I wonder if the spring the pushes up from the bottom isn't as strong as it should be. Or when the shutter button is released, it isn't traveling up high enough.

You were the closest... I had replaced the spring with 2 others with the same problem.. However it got me to thinking I had not checked the closing curtain latch so I replaced it with another and the B setting started working right..

Looking at the original one I found it was bent most likely by someone trying to adjust the 500th and/or 1000th speed without blocking the closing curtain latch which will result in a bent latch...

 

[martin_t]

You were the closest... I had replaced the spring with 2 others with the same problem.. However it got me to thinking I had not checked the closing curtain latch so I replaced it with another and the B setting started working right..

Looking at the original one I found it was bent most likely by someone trying to adjust the 50th and/or 1000th speed without blocking the closing curtain latch which will result in a bent latch...

Good Lord .......