Zenit EM complete CLA ongoing thread (pic heavy)

jaeae · Oct 20, 2020

I just bought two EMs from Ebay, both from late 70's. The other is worn and rusty (cost under 4€), second one is much cleaner. To my surprise both of them work, and have intact shutter curtain rubbering (!). The selenium cell metering also works. Over 40 year old cameras after all. It really shows that you should not buy a mint camera from Ebay, the one with use marks might just work better.

I decided to start from the beaten up one, I'm going to ignore all the rust and just make it work nice and not touch anything cosmetics.

For tonight, I disassembled the top part.

1. Cock the shutter and rotate the top plate clockwise (reverse threaded). I use snap ring pliers that have their pins filed to fit (sharper). Then remove 3 screws that hold the lever

2. Loosen all set screws around shutter dial and shutter button

3. Note that you may have 1 or more shims here and there. Don't loose them

4. Remove film rewind knob (2 screws + long spring). Then you have to improvise a tool to remove top collar and exp calculator. Under it, there are 2 screws that hold the top cover in place. One is next to the shutter cocking lever.

jaeae · Oct 20, 2020

Shutter button assembly

Some fancy looking fungus or something. I need to replace the prism..

jaeae · Oct 21, 2020

Clean focusing screen as always, they have put sticky substance around the edges that catches possible dust particles.

To lift out mirror assy remove 3 top screws

And the bottom cover

Seems that they put more effort to dampen internal reflections in the 70's. Stuff from the 90's aren't this matte..

Here's also a video how to lift the assy

4season · Oct 21, 2020

Thanks for posting this, I have an early silver-dial Zenit E that I've been meaning to work on.

In cases were it's not practical to replace the prism, I wonder if it might be possible to restore it by scraping away damaged coatings and repainting with a mirror-finish paint such as this:
https://www.rustoleum.com/product-catalog/consumer-brands/specialty/mirror-effect/
I have a badly damaged Olympus prism that I may experiment on.

Kino · Oct 21, 2020

4season said:
Thanks for posting this, I have an early silver-dial Zenit E that I've been meaning to work on.

In cases were it's not practical to replace the prism, I wonder if it might be possible to restore it by scraping away damaged coatings and repainting with a mirror-finish paint such as this:
https://www.rustoleum.com/product-catalog/consumer-brands/specialty/mirror-effect/
I have a badly damaged Olympus prism that I may experiment on.

I did that with an OM 1 and found that unless you get every little bit of silvering off the surface, it shows up as annoying ghost lines. Also, the spray mirror coating reflects a "cooler" wavelength of light, so any sliver left looks a bit warmer. It's not the greatest fix, but it does work.

foc · Oct 21, 2020

Thank you for sharing.
I have this bookmarked as I want to follow your progress.

AgX · Oct 21, 2020

4season said:
In cases were it's not practical to replace the prism, I wonder if it might be possible to restore it by scraping away damaged coatings and repainting with a mirror-finish paint.

A classic method of silvering is the one named after Tollens or Liebig, where a sugar is used as reducer of a silver-salt.

In most chemical experiments on this a glass hollow body is filled with the reactants and inside a silver coating appears (christmas ball). But silvering on the outside is possible too.
See here:
http://www.otterstedt.de/atm/silvering.html

But with this silvering thing we are spoiling this disassembly manual...

jaeae · Oct 22, 2020

Today I removed the shutter assembly.

Rotate top using thin wire etc (counter-clockwise). The pliers may leave a mark but it does not matter on the shaft

Remove screw completely

CAREFULLY nudge the shutter timing wheel with flat driver. Mine was quite tight because the screw hole had malformed a bit

Loosen the curtain tensioning springs (CW). You may want to leave just a tad of tension. This way, the curtains will stay put when you pull the whole assy out of the camera

Loosen (but don't remove) the screws holding shutter button spring (the metal plate). Pull out the plate and retighten screws. They also hold the light blocking plate on which the curtains slide, that does not need to be removed.

jaeae · Oct 22, 2020

This pin is for the self-timer release (goes in to the hole)

Remove the left side light plate. Note that you might want to re-install the screw as it also holds the aperture stop down lever hinge (so that it will stay out of the way)

Next you can DROP out the shutter assy. It's better if you press the shutter drum shaft slightly, so it stays in the bottom plate hole. Some newer Zenits have a lock ring there, so they are easier to assemble. But the EM does not.

It's a good idea to mark the position of the wheels and such to guide when you re-assemble, BUT it's not essential. The mechanism is so simple that you can figure out the correct positions with some trial and error.

foc · Oct 22, 2020

jaeae said:
Some fancy looking fungus or something. I need to replace the prism..

I have only ever seen this type of markings on Zenits.
Soviet fungi?
Never to be seen in the decadent and capitalists west.

Joking aside, your detailed photos are great. I am following this with great interest.

Kodachromeguy · Oct 22, 2020

This is very interesting. I am impressed by the many machined parts and small fittings and screws in the assembly. Were these cameras assembled by hand?

AgX · Oct 22, 2020

Yes.

see here , here

This applied on all european camera manufacturers. Automation/robotics was only used at drilling/milling. For instance Pentacon had a huge automatic machine for this.

Basically there were two concepts:

-) conveyor belt - where every worker assembled/aded only few parts, before the assembly went back onto the belt

-) nest - where a whole camera is assembled by just one worker

KMZ applied both concepts, depending on model of camera.

Of course the Zenit was assembled along a belt (even visible in that first photo).

jaeae · Oct 24, 2020

I was not going to do this but since it's simple (just take out screws and lift off) I cleaned the old grease from the winding gears. If these are not well greased you'll get the "grinding gears" -like film advance feel.. Also, this is the only place you can grease significantly. Many other places, like the shutter itself, you only must add a tiiiiny amount of grease to certain places or not at all.

Here's the shutter winding and release gear. It's inside the film advance sprocket "barrel". The small tip on the gear is responsible for releasing the 1st curtain.

jaeae · Oct 24, 2020

Kodachromeguy said:
This is very interesting. I am impressed by the many machined parts and small fittings and screws in the assembly. Were these cameras assembled by hand?

Yes and I must say I'm impressed by the workers that put these together in the USSR. Because all the parts, especially ones made from thin sheet, are cheap and coarse. They require some twisting and adjusting and fiddling with when they are screwed into place, and the workers have managed this very well.

In Japanese cameras, the parts just slide in and you are done. BUT they have 10x more parts and they are half the size of Zenit parts.

Tel · Oct 24, 2020

Some years ago, I owned an assortment of movie cameras including a couple of Konvas 2M/7M cameras and two Arri 2Cs. The Konvas cameras (also KMZ products) had parts that were machined to somewhat lesser standards than the Arri cameras. But they were designed with much simpler mechanisms, which made them easier to maintain in the field. The Arris were less friendly for field maintenance, but all the parts were literally interchangeable because they were machined to the exact same tolerances. The Konvases were cruder machines but they almost never broke down. It seemed to me that they were hand-made individually; stripping one down, I could imagine a technician making small adjustments to the parts to make them work together--a practice that would make part-swapping problematic.

But the KMZ techs were capable of fine quality work. I also owned a Kinor 35N made in 1986 (on the verge of the Collapse) that was still working perfectly when I gave it to a former student last year. (Edit: the 35N was a crystal-controlled synch camera that could hit and hold a perfect 24 fps every time you fired it up.)

jaeae · Oct 30, 2020

Today I cleaned the shutter gear assembly. I put a tiny amount of light oil into the conical spring gear and equally tiny amount of regular lithium grease to the mirror flipper wheel axle. The mirror flipper wheel has the most stress (pressing the wheel towards the bottom) and it has been greased from the factory as well. Otherwise no oil or grease to the gears, they need to run freely without stickyness.

Here's the mirror flipper wheel

The start/end point gear has a special bearing that is adjustable in tightness and has a VERY delicate copper shim in it. Don't bend it as I did. It's a bit tricky to adjust, but correct way seems to be to put the screw to "a bit too tight" setting, keep it there while tightening the nut on the opposite side, then do final tightening of the screw clockwise. Rotating the screw clockwise also loosens the bearing a suitable amount.

jaeae · Oct 30, 2020

Also I noticed that the upper curtain string has worn for some reason. I might try to replace only that with a spare one from a 122 (yes the curtains are just the same in 1979 EM and in 1994 122..)

I already started to dismantle the curtain edge. I might just ruin it, but I have more used spare parts to try if it fails..

baachitraka · Oct 30, 2020

Wow and nice to see. I got a broken Zenith but no guts to open it and mine is broken mirror assembly and as well as shutter.

jaeae · Nov 2, 2020

Today I've been putting the one replaced shutter string back to the shutter "blade". It wasn't as hard as I thought, you just need to use sharp knife to open shutter blade edge. I carefully pressed it back again with a flathead screwdriver and then between table vice softened with painter's masking tape. There's also some glue there to ensure the string also stays in the blade.

I have been experimenting with these 2 glues both are "sort of" contact glues for fabric. The BISON rubber seems a bit thick for the job, I may need to apply less of it in the future. See below picture

The "BUTAPREM" is a Polish rubber contact glue, it's very thin and does not mess things too much, seems optimal for many projects. Both glues do not adhere too well. Sort of like a strong tape. So you can dismantle things again if needed.

The shutter in this EM was operating OK in the sense that the curtains were not detached - but the factory glue was just gone to dust and barely held the curtains on the rollers. Just barely. Still they hold enough..

jaeae · Nov 29, 2020

I had to disassemble and clean one Jupiter-9 so this project has had some break but now it might continue.

I glued the one curtain string back to the main roller. But how to ensure it is straight, glued to the same lenght as the other one? I figured that it's no use to try to measure it, since the strings are not equal (just thereabouts) and how do you measure something that is on a round roller, within 0,5mm?

This method worked ok;

1. tape the string on the roller from it's end using painters masking tape
2. roll the curtain so that the blade comes close to the rollers. this way you can visually quite easily see if it's straight or not (see photo below)
3. adjust if necessary
4. when you think it's ok, use a very tiny drop of super glue and glue the end of the string to the roller. assemble shutter and test
5. if all is OK, disassemble + glue the rest using contact glue

jaeae · Dec 21, 2020

Found out why the upper string had worn. This Zenit probably had 2 faults right from the factory.

The upper roller on the curtain shaft did not have it's hole drilled entirely through. It did rotate but the position was wrong, so that the curtain string was rolling on it only halway. Also, the 2nd curtain had been glued a bit crooked, which meant one of the strings pulling it was tight and the other loose. I fixed it by exchanging the 2nd curtain from a 122.

jaeae · Dec 21, 2020

Correct position for glueing strings on the 2nd curtain tensioner

There has been a tiny amount of grease on curtain axles of every Zenit I have disassembled. So I put some fresh also, but only this much. However I think they would operate well without any lubrication.. the axles are steel and the drum is brass. If there are service experts here, what do you think?

jaeae · Dec 21, 2020

Here's some pictures how I assembled the shutter.
First align the curtains on a table like this

Put the shutter chassis on the curtains and then axles in their holes

[url=https://flic.kr/p/2kj3hEJ]

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jaeae · Dec 21, 2020

Then put some tension (just a bit) to the drums so the curtains will stay put.

Ready to be lifted to the camera chassis:

Here you can see how the upper bearing should be aligned to the shutter drum

jaeae · Dec 29, 2020

If the shutter assembly doesn't want to go easily to the camera chassis, most likely the light blocking plate is poking to the camera chassis or the shutter axles are not going to their holes in the camera body. So check those.

Then you should install the bearing and the shutter assembly with a couple of screws. Install the shutter latch mechanism / pin / hook also and you should have a working "B" mode. Check the shutter movement WHILE cocking it:

And when you open the shutter in "B" mode, the 1st curtain blade should be just outside the film opening at the left. 2nd shutter blade should be "waiting" at the right, optimally some millimeters before film frame opening (not just at the edge).

Zenit EM complete CLA ongoing thread (pic heavy)

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