Zenit 3M repair help

Hi guys,

I've had a Zenit 3m (which needed new curtains) in pieces in a box for ages. I've been having a go at piecing it back together today, the new shutters are in, but I cant seem to get it back together. When I've put the bottom of the shutter cage and the shutter rollers in the shutter only cocks half way. The camera wont wind any further than about 1/4 of the way. The shutter "releases" when I press the shutter release, I dont have the mirror installed as of yet, but i have been depressing the little lever that the mirror hits to stop the shutter opening before the mirror is up, so I dont think this is the problem.

Any ideas?

Thanks in advance :)

Rob

Anyone?

I did a Zenit 3M some time ago, and it isn't the easiest camera to put back together. I remember it took me 4 or 5 times before the camera was properly put back together.

The gears beneath the main shutter drum have a stop (when the camera is fully wound) When the drum is installed in the wrong position the camera won't fully wind. Also make sure the pins of the smaller drums fit in the holes on the top of the camera body, otherwise the shutter crate won't fit properly.

When the camera is wound, the lever for the second curtain on the top of the drum should be under the 'catcher' (a little further could be possible as well)
There is a gear which lifts the mirror, this one should be in the right position to release the mirror before exposure takes place.

I wish you good luck and patience. :)

Thanks for the response :)

When you mean the "catcher", do you mean the arm type part on the top of the shutter drum? the one which is formed by a circular slot? and should it be aranged like in the top picture of the following link?

http://jay.fedka.com/index_files/Page477.htm

I have wound the restricting gear to its counter-clockwise limit.

Is this correct? or do you speak of the parts right on the top, the ones that set the shutter speed?

Black noise
the curtains of 3M FED and Zorki works the same way, In the Jay pages it was omited a litle gear that works together the bottom curtain gear spool- that is the opening curtain - teeth must be Matched!. Forget the closing curtain. But it is important that the curtains be correctly positioned!
I never replace the new curtains unless the mechanics are working properly in an all assembled camera!
Normal proceedings:
1 reassemble the camera without the curtains and without all the mirror mechanics top and bottom. Remove allso the cocking arm that works through the wall gear that is in the advance mechanism.
2 Put all axel parts including speed crown ans sector and selector.
do not place synchro tower.
3 try to put the camera into operation and see if the speed selector
is working the full 300 degree rotation!in the proper position.
How to determine the position?
When selector is in the "B" position the gate will be closed.
In the "30" position there is a slight touch of the selector inthe gate.
You must work the camera by your hands once there are no springs to work the mechanics
The limit of the drum is done by a free gear in the internal of the chamber. try to match those gears slight opening the bottom of the camera and trying to do so by trial and error tentatives.
Once this done I will continue explanations.
regards and good luck. Do that with patience do not force anything.
LP

Thanks for all the help Luiz, but I'm still a little confused...

Do you mean I should remove the curtains from the rollers again and re-assemble the camera? When you speak of the 'cocking arm' do you mean the small gear that meshes with the bottom of the large shutter drum and is driven by the film advance to cock the shutter? And when you speak of the 'gate', do you mean the little arm at the back (camera in shooting position) of the shutter speed selector that holds the second curtain? Also, how do I double check I have glued the curtains on in the right position?

Sorry for all the questions, but I just know your the man to help me! :)

P.s. The Sokol automat is still working well after your help :)

I am uploading the image taken from three pictures of Maizenberg catalog
http://www.ussrphoto.com/UserContent/1982009_zentac.JPG

1 If you took new factory curtains yet mounted in drum and spool , of course you do not need remove the curtains.
If you got only the new cloth curtains you need to remove them.
2 the main drum is composed wit a sool and an inner free drum.
Befor assemble the unit all parts must be absolutely clean otherwise the camera shall not operate. theccking arm and the gear I refer are
parts 3, 4, 5 pic 304

The gate is the hook under the spring around the curtain main rotating axle

You cannot know the exact position unless you have the original factory tool that holds tight spool and drum in the right position indicating the position of both. Also the curtains must be original with the right length of ribbons and panels.

Your camera must at first be completely assembled without the curtains and the internal mask os course like the three pictures I sent now

After that I will explain the correct movement of the main axle, before installing the curtains.

send your questions as soon you feel needig them.
regards
LP

Hi there Luiz,

That's cleared things up a bit, but I'm still a little confused as of what you mean by the gate, is it the small hook that catches the shutter speed setting parts, the one on the bottom left side of the first picture?

Also, I'm sure the curtains are identical to the ones removed, they came from a scrap Zenit TTL and I've checked them against the old ones.

Thanks

Rob

definition of parts

http://www.ussrphoto.com/UserContent/2282009_zentac2.JPG

Now after mounting the parts in the right position study the operational principle putting the parts into work.




http://www.ussrphoto.com/UserContent/2282009_zentac3.JPG


observe there is a limiting gear under this screw:



http://www.ussrphoto.com/UserContent/2282009_zentac4.JPG



the curtains should only be mounted after well knowing the operational basis. After understanding, You will see how simple it is.

Regards LP

Hi Luiz,

Thanks for the diagrams, they explained it all perfectly :)

I've had a 6am-2pm shift at work today, so I'm a little tired for camera repair now. So I'll have a shot at putting it together either tomorrow or the day after. I'll let you know when I've got it going.

Just out of interest, how do I know when I have set the restricting gear in the bottom of the shutter crate properly?

EDIT: I re-read your previous post, you line the little tab (not the one which is moved when the shutter speed is changed) with the gate when the shutter is cocked, am I right?

Rob

Of course the little tab BELONGS fom the tube you turn to change speeds.OK?
regardsLP

Obseve the picture Zenitac2.
The speed selector is in the "B" position and the curtain are released.
This is the right limit position when the gears are correctly adjusted.

Its all clear now Luiz, thanks so much for the help, should get round to putting it together by wednesday night, will let you know how its going.

Thanks :)

Rob

Sorry to bump this post to the top after such a long time.

I was at a camera fair the other day and saw a Zenit 3m (with the industar 50) for a very low price. There was a slight rattle, which didn't affect the operation, and when I opened the top up, was one of the small pieces of padding under the clamps that secure the prism, as I suspected. This was easily fixed, and I used to top off of my old 3M, which was in much better condition. This means I have the I-50 and the Helios for the working camera :)

Thanks for all your help Luiz, It will come in very handy when it comes to fixing another similar camera :)

Rob

While we are in the repair section, who knows how to soften a Zenit 3M shutter release without major disassembly?

I bought one from Cupog a few years ago, it works fine but the shutter release is pretty stiff...

Any cure suggestion is welcome!

Take care.

All 3M are a little stiff.
Try to advance the lever but hold its mevement slightly before the end. Release the shutter. If the shutter release is significantly smoother it will be needed an adjust on the rachet mechanism.
if not, it will be sufficient to lubricate the releasing system.
To do this, spray the camera with a WD or similar oil in the shutter release button, Under the advance lever, press rewind button and spray into. Also remove the four bottom screws of the chrome plate and lub under the large spring blade across the bottom chassis. point 7 at http://www.ussrphoto.com/UserContent/2282009_zentac4.JPG
Regards and good luck.
LP

Thanks Luiz for your clear explanations! I will follow your advice as soon as I have some spare time.