Contax lla ultrasonic cleaning

[Kevcaster]

With the help of Rik Oleson's and Mike Elek's site, the excellent pictures put up by pb908, and the commentary by Highway 61, I have stripped and cleaned a Contax lla and discovered that I was not thorough enough and it failed the 'shelf' test after only a few days.
The issues are with the hesitant self timer, a hesitant 1 second speed and 1/1250 blanking. I'm ready to go again and guess that ultrasonic cleaning will help. My questions relate to two aspects:
1. How difficult is it to remove the various assemblies. In particular the slow speed escapement, medium speed module and the self timer and what should I watch out for?
2. My machine instructions suggest just warm water or a dilute cleaning agent supplied with the unit. What cleaning agents would you recommend for these assemblies?
All help very gratefully received
Kevin

 

[Rangefinderfreak]

Water in the camera will be DEATH... even if you warm it and blow water away quickly.
I`d rather use a solvent like rubbing alcohol or purified gasoline and then a through lube work.

 

[sevo]

Forget the 1/1250s blanking - grappling with that means disassembling the coaxial roller and springs. Given that the top speed on cameras of that age usually will not settle to a reasonably stable value no matter what you do, it is not worth while the risk...

 

[colyn]

I`d rather use a solvent like rubbing alcohol or purified gasoline and then a through lube work.

Rubbing alcohol contains water.

I use Xylene in my ultrasonic cleaner..

 

[Kevcaster]

Water in the camera will be DEATH... even if you warm it and blow water away quickly.
I`d rather use a solvent like rubbing alcohol or purified gasoline and then a through lube work.

Thanks for the swift responses to this post. I'm now very pleased I asked the question. I had imagined that there would be a proper fluid but hard no idea what it might be. I'm unfamiliar with Purified Gasoline, what about 'White Spirit'? The type used for thinning paint and cleaning brushes in model making? This is freely available.
Kevin

 

[Kevcaster]

Rubbing alcohol contains water.

I use Xylene in my ultrasonic cleaner..

OK thanks, Xylene is freely available, I have ordered some and will try it out.
Kevin

 

[Kevcaster]

Forget the 1/1250s blanking - grappling with that means disassembling the coaxial roller and springs. Given that the top speed on cameras of that age usually will not settle to a reasonably stable value no matter what you do, it is not worth while the risk...

I had a feeling that this might elude me, good to have your thoughts. I'm a novice with some loosely acquired understanding of very basic mechanics. The Contax lla is a masterpiece of engineering design and it strikes me that all the linkages and gears throughout the Contax should result in dependable and repeatable actions. That is until the two factors that are unpredictable step in. 1. The friction acquired from years of dirt, grease/oil degradations and various corrosive chemical reactions, and ...
2. Spring tensions

I can live with 1/500th top speed and will likely have to!
Kevin

 

[Vickko]

Wow, a IIa is challenging if you want to take it ALL apart.
Have you looked here: http://www.zeisscamera.com/
It scared me away, from doing a full rebuild

 

[Highway 61]

You can use distilled water in your ultrasonic cleaning tube.

But to one condition : you must blow some pure compressed azote on the parts as soon as you take them off the bath.

No further corrosion to fear if you do this. Less toxic/dangerous than using Xylene.

The slow speeds escapement is a breeze to take off : two screws only. Same for the selftimer.

You may want to take the shutter box off the upper deck ; not that difficult (four screws). Once done you can drop the whole upper deck in the ultrasonic tube. Of course you will not put the shutter unit in it - this would destroy the shutter cords and the shutter ribbons.

Ideally you must tension the bottom roller spring so that the 1/25 is both accurate and the quietest possible. If the camera is a good one, the high speeds will work well under those conditions once it has been cleaned thoroughly. If you need to overtension the bottom roller spring so that the high speeds seem to work at the expense of a very noisy 1/25 only : not good.

At the end of the day : what Sevo wrote for the high speeds geartrain shafts. The problem with those cameras is that the 1/500 very often behaves like the 1/1250 after the "shelf test".

 

[Platinum RF]

I think the problem is we do not have a good service manual. I bought a copy of what it called repair manual in Germany as well as English, however, it only show you how to disassembling the camera but not how to adjust it. For example the how to adjust shutter brake or shutter tape length et al

 

[Kevcaster]

You can use distilled water in your ultrasonic cleaning tube.

But to one condition : you must blow some pure compressed azote on the parts as soon as you take them off the bath.

No further corrosion to fear if you do this. Less toxic/dangerous than using Xylene.

The slow speeds escapement is a breeze to take off : two screws only. Same for the selftimer.

You may want to take the shutter box off the upper deck ; not that difficult (four screws). Once done you can drop the whole upper deck in the ultrasonic tube. Of course you will not put the shutter unit in it - this would destroy the shutter cords and the shutter ribbons.

Ideally you must tension the bottom roller spring so that the 1/25 is both accurate and the quietest possible. If the camera is a good one, the high speeds will work well under those conditions once it has been cleaned thoroughly. If you need to overtension the bottom roller spring so that the high speeds seem to work at the expense of a very noisy 1/25 only : not good.

At the end of the day : what Sevo wrote for the high speeds geartrain shafts. The problem with those cameras is that the 1/500 very often behaves like the 1/1250 after the "shelf test".

Thanks for this, I saw another of your posts about the 1/25th speed and would like to pursue that. I understand the problems of over tensioning. I'm uncertain about how to do the actual tensioning as yet and suspect that this camera may benefit from de-tensioning.

I like the idea of removing the shutter assembly and dunking the lot!
Azote (Nitrogen?) seems to be unavailable domestically or am I missing a proprietary name/pseudonym for it? I am wondering if it is something as simple as 'Dust Off' that comes in a spray can from Maplins etc.

All input continues to be very welcome.
Kevin

 

[Highway 61]

De-tension the bottom roller totally - the shutter won't fire.

Then, slowly tension until it both fires and gets accurate at 1/25 (you need a shutter tester or at least an old TV screen). As soon as 1/25 begins to get noisier, stop tensioning.

1/25 won't become faster with an over-tensioned spring - it will only become noisier.

If the shutter is a good one, and if it has been cleaned and relubed properly, it must work at all speeds (including 1/1250) with a super quiet 1/25.

There are some compressed azote (yes, nitrogen in English 😉) cans is many sciences universities labs, in general.

 

[Kevcaster]

Highway 61, I much appreciate your commentary on all of this.
I have a further test roll to develop tonight to confirm my suspicions and after that will start the strip down later in the week. I do not have a shutter speed tester or an old TV screen so I'm using an Audio recording suite to determine the shutter speeds on those that fully open the film gate - 1sec to 1/50th. It is fairly easy to determine peaks of the open and close sounds and of course it will not work on those speeds that rely on a 'slit' for exposure speed.
I can speculate that a recording will also reveal quite accurately the point at which the noise increases and the speed remains the same.
To de-tension: I notice a retaining leaf spring covering a gear on the bottom right of the shutter module as one looks through the film gate. Loosen the spring while holding the adjacent screw and allow it to turn anti-clockwise to release the tension? If not this then what is the procedure?
Kevin

 

[Highway 61]

To de-tension: I notice a retaining leaf spring covering a gear on the bottom right of the shutter module as one looks through the film gate. Loosen the spring while holding the adjacent screw and allow it to turn anti-clockwise to release the tension?

This is the correct procedure to de-tension.

 

[Kevcaster]

Good, very valuable and I will pursue this path.
The film test shows blanking from the 1250 and 500 speeds, the 250 runs 1/2 stop fast and the rest are consistent and good enough for b&w film. All other functions are excellent, so press on.
Thanks again for your input Highway 61, good of you to share your knowledge.
Kevin

 

[davidphillip]

May I add my 2 cents worth: I have overhauled about a dozen postwar Contaxes. I use watch cleaning "rinse" solution as a non-aggressive sovent which doesn't leave metal with excessive friction, as naptha sometimes does. If the shutter has been over-tensioned for long (this is quite frequent), the two fastest speeds usually won't be salvageable. 1/500 "works", but with uneven exposure. 1/1250 frequently barely opens. Also, take Henry Scherer's advice: use Moebius watch lubricants (Syntha-lube).
Best of luck.
David

 

[Kevcaster]

Thanks David, I have noticed the effect Naptha has on the surfaces of components and assumed it was a deposit, it may be as well as a surface effect. I have some Moebius oil.
The watchmakers rinse sounds appropriate, I will order some it seems widely available.
Yesterday evening I removed the top assembly from the body and de-tensioned the shutter. I'm busy recording the 1/25th while gradually re-tensioning the spring in line with the advice from Highway 61. On first go I can get all the speeds to fire with surprisingly little tension dialled in - 3/4 turn from just tensioned - but I wait to see the evidence of accuracy.
I also removed the slow speed escapement, self-timer and the shutter box. The first two I flooded with Naptha three times even though they had a clean previously. A fair bit of grit, grime and gunk was released and both are improved. They will still get an ultrasonic clean later this week. I also found 3 pieces of swarf released by a flooding of the wind on/shutter tensioning mechanism! They appeared to be very thin flaked chrome plate? - irregular shapes and no evidence of component damage so I conclude debris from a previous workshop or more disturbing debris from the Zeiss factory. I doubt the latter.
I will post some of the audio screen shots for interest once they are edited.
Thanks again for all assistance
Kevin

 

[Kevcaster]

These are sound recordings of a Contax lla shutter at 1/25th second marked speed - it should be 40ms. They show the effect of tensioning the shutter on both the speed and the sound. If a Contax shutter is over tensioned it leads to excessive wear and breakdown of the ribbons. In addition it affects the accuracy of the marked speeds. The bottom wave is 50ms and shows slightly more sound amplification than the top wave which is minimum tension and 57ms. The middle wave shows over tensioning , higher sound wave and shorter speed - about 45ms.

These are sound recordings of a Contax lla shutter at one second. They show the effect of tensioning the shutter on both the speed and the sound. If a Contax shutter is over tensioned it leads to excessive wear and breakdown of the ribbons. In addition it affects the accuracy of the marked speeds. The bottom wave is almost exactly 1000ms and shows slightly more sound amplification than the top wave which is minimum tension. The middle wave shows over tensioning , higher sound wave and shorter speed - about 900ms
Here is a handy tool for de-tensioning the shutter. 3 Toothpicks sellotaped together - works fine. Future models could be better in plastic.



Off to clean stuff ultrasonically.
Kevin

 

[Kevcaster]

Ready for testing with film.

After repair and service. Bought cheaply as 'broken' I stripped this and serviced it. There was evidence of previous service (s), I would say several over the years, the leather is worn smooth on the front left panel and some wind-on components show signs of heavy use. The body has a crazing of fine scratches and wear and tear has rubbed the paint off on the upper rear panel by the flash sync. All in all a well used but not abused camera. Today I will put a film through it and see if my work, works. If so then on to my colour dial llla.
Kevin

 

[Highway 61]

Nice work ! 🙂