Synchro-Compur MXV repair. Need help

[yurik_prshw]

I have a non-working copy of a Synchro-Compur MXV shutter. There are 2 problems with it.

1) The shutter fires right after cocking. Obviously, this mechanism doesn't work properly. As I understand, during cocking gear 1 moves in the direction of the arrow. Meanwhile, lever 2 moves towards the centre of the shutter and locks in that position. At some moment the gear 1 gets locked by flange 3. After firing the shutter lever 2 gets moved in the opposite direction and flange 3 frees gear 1 that makes shutter blades open and close.
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2) Sometimes the shutter blades are stuck. They simply don't open. After some attempts of moving them back and forth they move freely.

How to fix my shutter?

Nick

 

[Dan Daniel]

Oh my, where to start? There are so many little parts that need to be in the right position.


Probably best to post photos of your actual shutter. The drawings from the repair manual are far too clean and do not show what is going on with your actual shutter.

 

[yurik_prshw]

Probably best to post photos of your actual shutter.

2019-07-12_12-53-40

Idk if it is enough, so please tell me what exactly i need to photograph if needed.

 

[Sarcophilus Harrisii]

Shutter will also fire after cocking if the mesh of the main spring pinion to the cocking rack is a tooth or so out. Those parts are not installed in your image, so impossible to say if it's a factor or not but FYI.

 

[Dan Daniel]

Have you cleaned the shutter? Soaked in naphtha? That interior has more scratches than I think I have ever seen onside a shutter, so maybe it is all gunked up with oil or dirt.



And yes, having the cocking gear and rack installed properly is critical. As well as makiong certain that all levers are properly engaged in their slots and such.

 

[yurik_prshw]

Those parts are not installed in your image, so impossible to say if it's a factor or not but FYI

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This is the shutter before cocking without the cocking ring

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Same but with the ring

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Cocked


Stuck

Have you cleaned the shutter?

Yes

During the test the shutter worked correctly a couple of times (it fired after pushing the shutter button) but then it started working wrong again

 

[Dan Daniel]

Any oil applied? If so, where?

That part at the top center, #2 in your original labeling. It should be dropping down (toward center) and latching the cocking ring at the tab that is, in the last shot, aligned directly below it. The diagram you posted is the cocked position. So the cocking ring should be rotated slightly clockwise, not at the full stop position.

As this arm, #2, comes toward the center and latches on the cocking ring, it also does things lower down (well, sorry, I'm not totally clear so can't explain it but I know it is happening? that prevent other things from opening the blades like that.

Try this- cock the shutter, and as you let the cocking ring go back to home, push #2 to the center and have its tab stop the cocking ring from going all the way back to full stop position.

A little light oil in that pile of stuff below #2, including the pivot of #2 itslef, has gotten some Synchro Compurs working for me. Very light, try only for pivot points.

 

[yurik_prshw]

Try this- cock the shutter, and as you let the cocking ring go back to home, push #2 to the center and have its tab stop the cocking ring from going all the way back to full stop position.

A little light oil in that pile of stuff below #2, including the pivot of #2 itslef, has gotten some Synchro Compurs working for me. Very light, try only for pivot points.

I applied some watch oil on the axle and it helped a lot. So I have one problem left. To my mind, the shutter gets stuck because of some dirt which could get into some slots during soaking in the benzine. I'll clean it once more and then we will see.

 

[Dan Daniel]

How long are you waiting after any soaking? If I do any deep cleaning with naphtha, I need to make certain the interior is very dry. Open and close blades manually again and again, blow off blades each time as more liquid appears. My oven is gas and has a pilot that keeps the oven warm. So I will let the shutter sit in there for a few hours.


There seems to be a curve to the effect of cleaner in side the mechanism. At first, the liquid can act as a lubricant, making things move smothly. But as it dries out, the liquid becomes more of a glue as it sits in only some spots. Be sure to dry it out well.


And then sometimes there is just too much gunk and dirt inside the mechanism and it needs to be broken down. Take hundreds of close up photos as you disassemble. All angles, every part that comes off gets a few photos, etc.

 

[retinax]

That part at the top center, #2 in your original labeling. It should be dropping down (toward center) and latching the cocking ring at the tab that is, in the last shot, aligned directly below it. The diagram you posted is the cocked position. So the cocking ring should be rotated slightly clockwise, not at the full stop position.

It's possible that this is the whole problem. As someone mentioned earlier, when these shutters get "cocked too far", they fire.