Repair Copal SV shutter stuck on highest speed

[Mikey Antonakakis]

After studying the assembly a bit more, there are three main controls the shutter timing:
1) drive gear (don’t know the correct term, the partial circle-shaped gear) travel distance, as set by the bumpy cam. Has a pattern of full, half, quarter travel (1s, 1/2s, 1/4s), repeats for 1/8-1/30, then repeats once more with added one-eighth travel for 1/60-1/500.
2) gear ratio lever - between 1/4s and 1/8s, the gear ratio of the escapement changes, it stays in the faster ratio all the way to 1/500.
3) pallet engagement lever - between 1/30 and 1/60, the pallet is disengaged.

Between all these, it seems the only action that could be adjustable is the drive gear distance, as mentioned by adjusting the swaging and/or the entire escapement assembly position (thereby changing the travel). Gear ratio and pallet engagement are either on or off.

So, that leaves spring tension on the drive gear as the main adjustment, I suppose (if trying to adjust 1/60 and faster)? The Compur manual mentioned bending one of the levers for that adjustment so at least now I have an idea of what I’m looking for…

EDIT:
Okay, I see now - the escapement is actually driven by another lever (external to escapement assembly).

At this point, 1s to 1/4 is running a bit fast (0.9s, 0.4s, etc). 1/8 to 1/30 is nearly perfect. 1/60 to 1/500 still running slow - but 1/60 to 1/250 has improved a bit.

 

[Dan Daniel]

This image is stolen from post #12 in this thread. The slot and tab at the 'bottom' of the escapement affects the basic timing of slow speeds. You put a screwdriver in the slot to push the tab away from the slot. This will speed up the slow speeds. You push the tab towards the slot to slow down the slow speeds. Be gentle, patient. It won't take much bending.

The tab is the stop for the pallet as it interacts with the star gear. Moving the pallet away means less engagement and the star gear can wind down faster. Moving the pallet towards the star gear means more interaction, slower speeds.

 

[Mikey Antonakakis]

OKAYYY I think I get it now. The spring on the

This image is stolen from post #12 in this thread. The slot and tab at the 'bottom' of the escapement affects the basic timing of slow speeds. You put a screwdriver in the slot to push the tab away from the slot. This will speed up the slow speeds. You push the tab towards the slot to slow down the slow speeds. Be gentle, patient. It won't take much bending.

The tab is the stop for the pallet as it interacts with the star gear. Moving the pallet away means less engagement and the star gear can wind down faster. Moving the pallet towards the star gear means more interaction, slower speeds.

View attachment 365883

Ah excellent, thank you!

I realized last night that the spring on the cocking lever is what actually drives the escapement - the spring on the semi-circular gear inside the escapement assembly acts in the opposite direction in order to push the timing lever onto the cam during cocking.
The spring on the cocking lever appears to be adjustable but I am going to hold off on adjusting it unless it's absolutely needed. I may take another shot at cleaning shutter blades and cleaning and maybe lubricating the shutter ring.

 

[BrianShaw]

Use the lubrication specification in the repair manual rather than “maybe”!!

 

[Mikey Antonakakis]

Can't find a repair manual for SV anywhere... I will try SVE which I was able to find.

 

[Mikey Antonakakis]

I disassembled the shutter again and cleaned aperture and shutter blades individually and thoroughly. Fastest speeds are running a bit faster now - 1/250 improved from ~1/125 to ~1/190, and 1/500 is now ~1/250. Almost there!

 

[BrianShaw]

Given that the typical tolerances are up to 1/3 stop, you seem to be about where you should be. The fastest speeds, as you seem to well understand, will rarely be as advertized. Might be time to call it a day. Congratulations; Enjoy the camera!

 

[Mikey Antonakakis]

Minor update - after applying a little oil to the main lever and to the drive lever in the escapement assembly, and working the shutter a few dozen times, it's basically spot-on at all speeds now! 1/500 is now somewhere around 1/450, give or take, 1/250 is right on (maybe a tiny bit fast), and all other speeds are nearly perfect (except 1/30 which is running on the fast end of spec). Quite pleased! Going to close up the camera now before the magic disappears!

 

[reddesert]

Bear in mind that "shutter efficiency" affects leaf shutters at the highest speeds. At the highest speed, the time it takes the blades to open is comparable to the overall speed. This means that the effective open time at a small aperture is longer than the effective open time at large aperture. Depending where you put the photoresistor to do your measurements, you might be measuring a narrow beam of light through the shutter and getting a slightly longer time than the effective open time for a large aperture. That's a mouthful, but basically, don't get too worried if you measure the fastest speed as a little slow.

 

[Mikey Antonakakis]

Bear in mind that "shutter efficiency" affects leaf shutters at the highest speeds. At the highest speed, the time it takes the blades to open is comparable to the overall speed. This means that the effective open time at a small aperture is longer than the effective open time at large aperture. Depending where you put the photoresistor to do your measurements, you might be measuring a narrow beam of light through the shutter and getting a slightly longer time than the effective open time for a large aperture. That's a mouthful, but basically, don't get too worried if you measure the fastest speed as a little slow.

Yup, that shows up quite clearly the way I'm measuring it - close the aperture and the same measurement points (very start of the rise in the signal and very start of the fall) get further apart (and the closing point is a lot easier to distinguish, since the shutter blades are moving quite quickly by the point they pass the mostly-closed aperture blades - same reason 2-stroke engines have such loud exhausts, but now I'm way off on a tangent).

If I cared a little more I could actually measure the change from smallest to largest aperture, which would give a good idea of how long it takes the blades to open and close, but it won't help me take better photos lol.

 

[Mikey Antonakakis]

"Final" measurements for the shutter, 5 readings at each speed, at two aperture values, after replacing my photoresistor with a much faster response phototransistor, and with camera fully assembled.

Basically all speeds with pallet engaged are running a little fast - adjusting the pallet engagement was indeed very sensitive and I couldn't reliably get it running slower without stopping the mechanism intermittently. Still, within Compur spec for basically everything other than 1/500, and 1/30 is just barely out of spec. The consistency is also quite good. Plots are normalized to percentage (first plot) and "stops" (second plot).

 

[sagrotan]

Hallo,
I have found this post as I am looking for some information regarding the copal-sv. I have a Yashica Mat 124G with Copal-SV. The apperture and shutter blades were all messed up. I have disassembled everything so far and cleaned the blades, but now to my problem: I have no information, how the blades are arranged. There are many images for the Copal-MXV and a repair manual for Copal-SVE (which I have brought). But I am not sure, if the Copa-SVE has the same parts, as mine does not have spacers for shutter blades. The "diaphragm" blades are also 5 pieces. So to my questions: Does the Copal-SV has spacers? If yes, then someone has "lost" them... And second: Is this correct for Copal-SV (from manual Copal-SVE): "There are 5 diagphram blades, laid counter-clockwise with the tails (smallest portion) of the blades pointing counter clockwise. The diaphragm blade control ring should be turned to its most counter-clockwise position (as seen from the sutter front) for the wide open position".

Best regards and thanks in advance
Nena