Leica R8 disassembly - Part 1

[Zhenggg]

Advertisement (gone after registration)

33 minutes ago, rick_dykstra said:

It is the blue part that touches the solenoid. This is the 'steel bar' I've mentioned. Try to manipulate this, so it moves a tiny distance away from the solenoid. Or is it stuck? The solenoid is the black part (with the red and white wires) to the left of the steel bar.

When you push the trigger sear manually, it is normal to see no reaction from the steel bar and solenoid. By doing it manually, you've tipped the last domino in the sequence. The others that normally come before it are unaffected. However, when this group is working correctly, the solenoid pushes the steel bar away, which allows the next part to move by spring action, which allows the trigger sear to release the main spring mechanism. It's like a game of Mouse Trap.

I've watched the slow-motion. It doesn't help establish whether the steel bar is being pushed away by the solenoid. So, push the steel bar and watch closely to see if it separates from the solenoid. It will spring back immediately, so could be difficult to observe. However, simply manipulating it could free it up.

Check if I’m right.

P1 is “cocked, fired, but mirror up” config, and in this configuration I can indeed, as demonstrated by the blue arrow, push the blue component (the steel bar).
By pushing according to the blue arrow, the blue component pushes the yellow squared part of P2, this “rotates” the yellow component and is equivalent to directly pushing the sear. And then mirror is back to normal position.

SO if I’m not wrong, the blue part is movable (not glued to the interface of the solenoid, and there left two possibilities: (a) electronic issues regarding the solenoid, there is no (anti?)current when pushing the shutter release button, and thus the blue bar can not be pushed to rotate the yellow part. (b) the blue part is (over)magnetized, so that the force induced by the (anti?)current when firing is not strong enough to push it away.

(just for ref since this is not a canon community, situation (b) is exactly what causes the common-existing “BC error” of the early EOS models (especially EOS 1,1n))

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

Edited November 14 by Zhenggg

[Zhenggg]

1 minute ago, Zhenggg said:

Check if I’m right.

P1 is “cocked, fired, but mirror up” config, and in this configuration I can indeed push as demonstrated by the blue arrow. 
By pushing according to the blue arrow, the blue component pushes the yellow squared part of P2, this “rotates” the yellow component and is equivalent to directly pushing the sear. And then mirror is back to normal position.

SO if I’m not wrong, the blue part is movable (not glued to the interface of the solenoid, and there left two possibilities: (a) electronic issues regarding the solenoid, there is no (anti?)current when pushing the shutter release button, and thus the blue bar can not be pushed to rotate the yellow part. (b) the blue part is (over)magnetized, so that the force induced by the (anti?)current when firing is not strong enough to push it away.

(just for ref since this is not a canon community, situation (b) is exactly what causes the common-existing “BC error” of the early EOS models (especially EOS 1,1n))

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

Also want to know what the transparent plastic hood/cover (right to the solenoid) used for?

[rick_dykstra]

From looking at this main spring firing system closely, it's not clear to me that the firing solenoid does have a magnet to hold the steel bar to it. It might have, but it might not. Rather, it looks like the long spring, shown by the green arrow in the following picture, does the job of returning the steel bar to its resting position against the solenoid. There could be a magnet to help hold it there. Unconfirmed at this point. And this could mean that trying to demagnetise the steel bar might not be an appropriate action. Further investigation needed. 🙂

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

[Zhenggg]

10 minutes ago, rick_dykstra said:

From looking at this main spring firing system closely, it's not clear to me that the firing solenoid does have a magnet to hold the steel bar to it. It might have, but it might not. Rather, it looks like the long spring, shown by the green arrow in the following picture, does the job of returning the steel bar to its resting position against the solenoid. There could be a magnet to help hold it there. Unconfirmed at this point. And this could mean that trying to demagnetise the steel bar might not be an appropriate action. Further investigation needed. 🙂

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

Yes. I’m looking back into your disassembly video, hoping that reveals some detailed structure of the component. Thanks anyway, it’s lucky to have you in this community!

Regards,

Zheng

[rick_dykstra]

Re your comment #21, it's good to hear that the blue arrowed part is not adhered to the solenoid and that you can fire the main spring mechanism by activating it. As you've figured out, moving this 'steel bar' as I call it (because I assumed early on that it was attracted to a magnet in the solenoid, as is the case in other parts of the camera) causes the trigger sear to move, which releases the main spring mechanism.

I agree with your thoughts on the next two issues to investigate. 1 - the electrical integrity of the solenoid and 2 - whether the steel bar is magnetised to the point where the solenoid cannot push it away, given that it would then need to overcome this added magnetism and the force of the long spring I pointed to above. 

Can you measure the resistance between the two solder points on the flex tail? That will give us a clue as to whether the solenoid is shorted or open. There should be some resistance, but not too little or too much. The rest of the circuit could confuse the measurement, but if the solenoid is OK, the resistance should be in the tens or hundreds of Ohms. Not 2 Ohms and not infinite.

Edited November 14 by rick_dykstra

[rick_dykstra]

1 minute ago, Zhenggg said:

Yes. I’m looking back into your disassembly video, hoping that reveals some detailed structure of the component. Thanks anyway, it’s lucky to have you in this community!

Regards,

Zheng

I don't think my videos are going to be much help with this particular issue. The main spring mechanism's solenoid pushes the steel bar way, but it returns instantly. In other parts of the camera (not shown in my videos), solenoids push a bar way and it stays away, until returned to it's resting, cocked position against the solenoid.

Any luck with your multimeter, measuring resistance of the solenoid?

[Zhenggg]

Advertisement (gone after registration)

9 minutes ago, rick_dykstra said:

I don't think my videos are going to be much help with this particular issue. The main spring mechanism's solenoid pushes the steel bar way, but it returns instantly. In other parts of the camera (not shown in my videos), solenoids push a bar way and it stays away, until returned to it's resting, cocked position against the solenoid.

Any luck with your multimeter, measuring resistance of the solenoid?

Unfortunately I don’t have a multimeter now as I only moved to Belgium a few months ago and brought merely minimum equipments as I’m more like a photographer than a technician.

Fortunately I’m more like a physics grad than a photographer, so probably I can find some instruments from some EE dept. friends.

One more question still, I didn’t get an idea how the long spring (the one on the right hand side of the yellow/blue components) works? What it’s associated with and what’s its function in the triggering sequence? 

[rick_dykstra]

Something else I'm wondering about is the black discolouration on the pivot point for the steel bar and the trigger sear. I've added an arrow to your pic. Could this be gunking up the free movement of these parts? It's different from the same part in my camera. Hmmm..  Though, you did say that the steel bar is moveable. And I've seen that the trigger sear moves with your pen, the same as in my R8. So, there might be no effect from whatever has caused this discolouration. 

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

[Zhenggg]

That’s probably some oil-dust mixture, it’s indeed kind of strange to appear there.

For now I am more concerned about the long spring, I attached a pic regarding its relative position when cocked. Is it normal that its upper end is detached from the pivot?

And again could you explain the function of the long spring again, I didn’t really get it.

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

Edited November 14 by Zhenggg

[rick_dykstra]

43 minutes ago, Zhenggg said:

Unfortunately I don’t have a multimeter now as I only moved to Belgium a few months ago and brought merely minimum equipments as I’m more like a photographer than a technician.

Fortunately I’m more like a physics grad than a photographer, so probably I can find some instruments from some EE dept. friends.

One more question still, I didn’t get an idea how the long spring (the one on the right hand side of the yellow/blue components) works? What it’s associated with and what’s its function in the triggering sequence? 

I'll add a photo I've found which shows the relationship between the solenoid, the steel bar and the trigger sear. The long spring pulls the steel bar back to its starting position against the solenoid.

The green arrows point to the 'steel bar' and its associated, long spring, which pulls the steel bar back into its resting position against the solenoid.

The red arrows point to the trigger sear. It has a spring hooking over it, which can be seen under the head of the red arrow at upper-right. This spring pulls the trigger sear down, so it catches the main spring mechanism while being cocked. The dashed, red arrow shows the part of the trigger sear that is pushed by the steel bar when the solenoid activates to push the steel bar away. Edit: Hmmm, I'm not happy with the red arrow (that was previously) pointing to the coil spring. The picture you sent in post #29 makes me unsure that it acts on the trigger sear. Look at the colour and thickness of the spring that is hooking over the trigger sear. It looks different from the coil spring. There appears to be another spring on the pivot pin, beneath the brass coloured coil spring. You have your camera open, so can best assess this. Regardless, I'm satisfied that the long spring is pulling the steel bar back into its resting position against the solenoid.

I'm going to re-do this picture and take out the red arrow that is (was) pointing to the brass coloured coil spring. Done. This new picture should not mislead.

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

 

Edited November 15 by rick_dykstra

[rick_dykstra]

@Zhenggg 

Re your question in comment #29 and the blue arrows, this disposition of the end of the long spring could be due to the cocked or uncocked status of the main spring mechanism. Either way, it won't be affecting the solenoid's ability to fire the mechanism, as this spring resists the solenoid rather than assists it. I don't think it's a problem.

[Zhenggg]

Yes I think your are right about the long spring and that’s actually why I asked in #29. Since the spring is detached when shutter cocked, there seems no force resisting the solenoid pushing the steel bar away, it should be rather easy for the solenoid to push the steel bar away so that mirror go down. And given the steel bar is not adhered to the solenoid, the original two possibilities regarding electronic integrity and magnification are very convincing at this point. I’ll update once I find a multimeter.

[rick_dykstra]

I agree with your assessment at #32. For your benefit, I hope the problem is magnetism of the steel bar, which should be easy to resolve. However, if I had to put money on it, I would say the problem is more likely to be a dodgy solenoid. If it is the solenoid, repairing the problem will be easy once a replacement is found.

I'll watch for news.

[Zhenggg]

Hi Rick! Lucky me it’s magnetization.

I don’t know where to find an AC demagnetizer here in Europe, so my first attempt was to use a (strong) neodymium magnet which is easily accessible from Amazon.

The first several attempts weren’t very successful: as I tried to repeat what I used to do for fixing BC errors of early EOS models, the simple trick of “putting the neodymium magnetic above the solenoid component (and thus the weakly magnetized steel)” didn’t work. This could be the magnet I got from Amazon was just not as strong as the one, which is of strength N52, I used back in home for EOS 1n; or it’s some components had indeed lost lubrication.

Now that I don’t know where to get N52 magnets in Leuven, and even if I know, I couldn’t determine whether they were gonna work. What I can do with these weaker magnets? To mimic the effect of “(slowly) putting strong magnet toward the steel bar”— or roughly speaking, mimic an AC demagnetizer — we must “rapidly putting the weak magnet…”. More rigorously speaking, it’s all about the rate of change of magnetic field. So I just continued taking more attempts, using the magnet to knock around the steel bar (the lower end of it since that’s where it was magnetized). I put a photo to demonstrate where to knock your magnet at.

During like the first 20 or more attempts, the mirror can occasionally be “triggered”(meaning lifted up) by knocking the magnet, depending your angle, velocity, positions, etc. Then after about 30 attempts you can now complete the whole mirror-shutter-mirror process by simply pressing the shutter release button. At this stage the mirror stuck issue re-occurred many times and I had to lift the mirror by knocking (or our early trick directly manipulating the components). After about 100 dry firing (I think this is okay for a machine with EM shutter, but of course you can load a roll to avoid possible damage) , the mirror stuck issue stoped to occur anymore (at least for now).

At the end of the story, I really want to express my gratitude to Rick and this community, it’s so kind of you to be so generous sharing your knowledge with us!!!

Best regards! 
Zheng

 

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

[rick_dykstra]

Congratulations Zheng! You've succeeded in making your Leica R8 work again. I'm sure you're feeling good about that.

So, to help the search engines and their AI robots find this thread and draw attention to it for folks who might have the same issue with their Leica R8 (or other cameras with similar technology), let me paraphrase our discussion of the problem, the symptoms, the diagnosis and the solution. First, I'll define the events of an exposure cycle in the simplest terms. Events are composed of multiple actions, which are not all addressed here.

• Event 1. Mirror goes up & lens aperture blades close. While these are two actions, they are triggered by the same solenoid, so I'll include them within the same event. A shutter release signal causes the camera's microprocessor to command a solenoid in the mirror gearbox to push a steel bar away from it, which releases two trigger sears. One of these releases the mirror, which is pushed up by a spring. The other releases a hook in the gearbox, which can then free-wheel while the aperture spring in the lens closes the aperture blades.  
• Event 2. The first curtain of the shutter fires. The camera's microprocessor commands a solenoid in the shutter to release the first curtain.
• Event 3. The second curtain of the shutter fires. The microprocessor commands a second solenoid in the shutter to release the second curtain.
• Event 4. The main spring mechanism fires, pulling the mirror down and the aperture open. The microprocessor commands the main spring mechanism solenoid to push a steel bar away from it, which pushes a trigger sear, which releases the main spring mechanism. Two actions from this are: the main spring mechanism pushes on the mirror return arm, thereby lowering it, and; a toothed rack is pulled, which pulls gears in the mirror gearbox, which rotate the aperture opening tab, which pulls the lens' aperture blades open.
• Event 5. The main spring mechanism is re-cocked. I've called this Event 5 because I came up with this list while trying to diagnose why my motor winder would not cock the main spring mechanism at the end of an exposure cycle. A person who only ever uses the manual wind-on lever just before making an exposure might prefer to put this event at the start of the list. When the main spring mechanism is re-cocked, the strong spring tension of this mechanism is made ready to pull the mirror down and re-open the lens' aperture blades. This serves as a good example of how many actions within the camera involve a strong spring resetting the position of an item that was first moved by a weaker spring.

With your Leica R8 SLR camera, the mirror was not coming down after the second shutter curtain had fired. That is, Event 4 was not occurring. We didn't talk about it, but another symptom would be that the lens' aperture blades would not re-open. The bottom of the camera was removed, which made it possible to push the main spring mechanism's trigger sear, causing the main spring mechanism to fire. Through this action, the mirror would be pulled down and the aperture blades would open. This result shows that the gear box for the mirror and aperture in your camera has been OK all along.

With the bottom of the camera removed it could be seen that pressing the shutter did not cause the main spring mechanism to fire. Of course, another clue was the absence of noise of the main spring mechanism firing. A few, possible causes for the main spring mechanism not firing were established, being:

• the 'steel bar' that is normally parked against the main spring mechanism solenoid might have become magnetised over time, such that it was being held to the solenoid by too strong a magnetic force for the solenoid to overcome;
• the solenoid might not be working, electrically;
• the steel bar might be adhered to the solenoid, by corrosion, gunk, etc, and;
• the pivot point for the main spring mechanism's 'steel bar' and the trigger sear might be corroded or gunked up, such that free rotation of these parts is impeded.

You established that the 'steel bar' was not stuck against the solenoid. The steel bar and the trigger sear were pivoting freely. The springs acting upon them were intact. Measuring the resistance of the solenoid, to establish whether it was shorted or open, was planned but a multimeter was not available. This left the possibility of magnetisation of the steel bar which lies against the solenoid as the next, convenient issue to investigate. Without further disassembly, you used the repeated movement of a magnet against the steel bar to change it's state of magnetisation, which allowed the solenoid to do its job and push the steel bar away from it. Success! And well done. You win the bet. 🙂 

Regards, Rick.

Edited November 15 by rick_dykstra

[rick_dykstra]

In case someone is reading comment #34 while trying to diagnose a problem with the main spring mechanism solenoid, I'll add some clarifying notes to the observations made by Zheng.

In the fifth paragraph Zheng mentions that while knocking his magnet to neutralise the magnetisation of the 'steel bar' which is parked next to the solenoid, on occasions the mirror would be 'triggered' and lift up to the raised position. I'll mention here that this is not happening because of any affect upon the main spring mechanism (including the solenoid), as its job is to pull the mirror down and pull the aperture blades open. Rather, I suspect that the mirror was being released and allowed to lift up due to magnetic effects upon one of the solenoids in the mirror gearbox and the metal bar that is held by magnetic force against it. I described these parts in Event 1 in comment #35.

In the same paragraph there is mention of concern about firing the main spring mechanism, whether by the shutter button, or pushing the trigger sear, or knocking a magnet to overpower the magnetic force of the solenoid's magnets. Yes, these actions can cause the main spring mechanism to fire, but the resulting strong movement is no different to what happens normally. At times, while performing tests with the main spring mechanism, I would cushion its strong, fast movement with my thumbnail. I would do this if other pieces such as the circuit's flex tails were out of their normal position, risking damage. Certainly, the main spring mechanism makes a lot of noise when it fires and it sounds worrying.

Further, to the question in the same paragraph on whether it might be an idea to use a roll of film to avoid possible damage, I would say 'No!' and quite loudly. Film is the last thing you want to put in a film camera, if avoiding damage is preferred. Film in cameras is like patients in hospitals - nothing but trouble.

[AdrianFinch]

Hi Rick, since you have once disassembled your R8, do you have any clue on how the shutter speed dial works? 
My problem is kind of weird: when I select speed between  1/1000 and 1/3000, the shutter will actually work on 1/8000 (and so is the finder display); when I select speed between 1/4000 and 1/8000, the shutter will work at 1/1500 (and again, so is the display). The camera is otherwise working properly, for example, in A mode, all shutter speeds are usable, and the speeds missing in M mode are also available (and the LCD display shows them properly).

Given what I have seen, I suppose it’s not a malfunction of the shutter (or its circuit), or of the display (since all speeds are available in A mode), and probably something related to the speed selecting dial. This is not something intolerable since generally I use aperture priority, but it would be better if I could fix it.

Thanks in advance, and it’s amazing to see someone finally posted about servicing an R8/9 and you have already helped someone fix his/her camera, given Leica itself has quit servicing this model.

[rick_dykstra]

3 hours ago, AdrianFinch said:

Hi Rick, since you have once disassembled your R8, do you have any clue on how the shutter speed dial works? 
My problem is kind of weird: when I select speed between  1/1000 and 1/3000, the shutter will actually work on 1/8000 (and so is the finder display); when I select speed between 1/4000 and 1/8000, the shutter will work at 1/1500 (and again, so is the display). The camera is otherwise working properly, for example, in A mode, all shutter speeds are usable, and the speeds missing in M mode are also available (and the LCD display shows them properly).

Given what I have seen, I suppose it’s not a malfunction of the shutter (or its circuit), or of the display (since all speeds are available in A mode), and probably something related to the speed selecting dial. This is not something intolerable since generally I use aperture priority, but it would be better if I could fix it.

Thanks in advance, and it’s amazing to see someone finally posted about servicing an R8/9 and you have already helped someone fix his/her camera, given Leica itself has quit servicing this model.

Hi Adrian.

It's fun to work on these cameras. I enjoyed breaking through the barrier of making my first move to really open up my original R8. And then fix it. Please feel encouraged to dive in yourself.

I think you've worked out the most likely diagnosis. It sounds like the shutter speed dial is gunked up. I didn't need to touch mine, but once the camera's top is off, it looks to be an easy job to get it out. A squirt of CRC CO Contact Cleaner or equivalent (Servisol, or De-oxit?) and then some dial spinning, perhaps with a follow-up squirt of cleaner, should do some good. Make sure to thoroughly dry anything you've cleaned before reconnecting or allowing any electricity to flow through it. 

Edit: The CRC CO Contact Cleaner I have says it behaves nicely with plastic. Yeah, still, try to avoid soaking the top of the plastic dial with the spray. Aim to get at the electrical contacts only, if possible. Use as little as possible and necessary.

Edit 2: Once you've lifted the lid off, you might be able to leave the main flex-tail between the camera top and camera body connected, while you remove the shutter speed dial and its flex-tail. However, if you feel confident, go ahead and disconnect the main flex-tail between the top and body first, as seen in my Part 1 video. I've just watched that part again; it took a little longer than shown as I worked carefully. Some fine, bent-nose or straight pliers would help. Another technique for pulling the flex-tail out of an opened connector is to use the flat end of a spudger to gently prise the tail out. Twisting the spudger between the connector and the flex-tail's stiffening reinforcement can work to pop it out.   

Another (but far less likely) possibility is the flex-tail connector for the shutter speed dial. Simply disconnecting and reconnecting this could be enough to clear any oxidation. Cleaning is an option. 

So, grab your Phillips 00 screwdriver, a set of fine circlip pliers (straight ones will work) and a plastic spudger and get that camera top off! Enjoy. Oh, and you'll need a sharp-ish fingernail. The girls in the Part 2 video will be cheering you on.

Regards, Rick.

Edited November 17 by rick_dykstra

[AdrianFinch]

Ok some updates on messy shutter speed.

1). Searched over many ancient forums, found 1 similar case back in 2000s, user reported messy shutter speeds (except for a certain range) on a 22xx R8, fortunately or unfortunately Solms still serviced the model back in that time, so no valuable info about where the error originates. However, this case indeed support this problem might be common in 22xx (first batch) R8.

2). Removed the top cover and unplugged the FPC connecting the shutter speed dial, the shutter speed is then fixed at 1/1500s, meaning this is the default config of shutter speed. Thus the mismatch “1/4000,…,1/8000 \mapsto 1/1500” is probably “no signal and set to default”; while the “1/1000, …, 1/3000 \mapsto 1/8000” mismatch might have a different origin. 

3). By cleaning the contacts, I can recover 1/1000, while 1/1500~1/8000 still messy.

[Advertisement]

Hallo,

Look here: Interesting Leica gear

[rick_dykstra]

2 hours ago, AdrianFinch said:

3). By cleaning the contacts, I can recover 1/1000, while 1/1500~1/8000 still messy.

Hi Adrian.

Well done on diving in. The cleaning you’ve done seems to have had some effect. Can the shutter speed dial be disassembled further, to allow you to see the condition of the contact strip? I’m wondering if grit, salt deposits, or corrosion are stopping smooth running of what I expect is a continuous potentiometer, similar to the contact strip in the body’s aperture sensor. Pictures would be helpful.

If you do disassemble further (I don’t know if it’s possible but I’m thinking it should be), watch out for a tiny ball and spring which might go flying. These will provide the clicking as the dial rotates. Be careful if you’re cleaning the contact strip directly. Gentle wiping with a cotton-wool bud (Q-tip) wet with cleaner could do the trick. Try to avoid leaving fluff behind.

 Are there any electronic components on the circuit near the shutter dial or under the camera top? Condition? I don’t have clear photos of this area, but my videos might have some useful views. I’ll look. I’m thinking about what kinds of signals the circuit here sends to the body; direct voltage readings or something more sophisticated.

Edited Thursday at 08:18 PM by rick_dykstra