This is a copy of a post I made to Facebook.

YASHICA FX-A

Now here's something you may not have seen before, or ever see again, it's the rarest of Yashica SLRs, the FX-A.

There's not much information around about the FX-A. It was introduced at Photokina in 1982 but the plug was pulled on the project soon after and there was only, allegedly, around 1000 made, most of which, allegedly, were bought by the US Government. I'm not sure any of this can be verified but it's a fact that few were made and they rarely show up for sale.

The FX-A has built-in focus-assist so is a predecessor of the later Contax RX. It is not auto-focus and I, personally, can't see how it could ever have been an auto-focus camera as there are no couplings to the lens that would allow the lens to be controlled by the body. I think this was only ever going to be a focus-assist system, just like the RX. At the same time, Yashica were developing a AF version of the Contax 137 which may have been a full auto-focus system - we'll never know.

The FX-A has been described as similar to the FX-D. In fact it has very little similarity to the FX-D and it would be misleading to say it is. It is a generation later than the FX-D and the style and build are much more similar to the FX-70 and the FX-103. Both of these cameras came later so it seems some of the development of the FX-A did not go unused and appeared in these later cameras. The shutter, particularly, is different than the FX-D or any earlier cameras but the same shutter was carried over into the FX-70 and FX-103. Other parts and assemblies also got reused in the later cameras.

If I am being perfectly honest, the FX-A, along with the FX-70 and FX-103, are not built as well as the FX-D. Maybe this was the result of cost cutting measures, perhaps due to Yashica's financial woes of the time prior to the Kyocera take-over.

It seems the camera was intended to have a number of accessories including a winder and a data (or date) back. There are four winder contacts on the base suggesting the winder would be based on the Contax 159 winder which also has four contacts. But one of the contacts on the FX-A is not connected so it would have had less functionality. The Contax 139 winder fits and works as intended. The later FX-103 also had four contacts and a winder which looks identical to the Contax 139 winder so this was probably what was intended for the FX-A. The 139 winder only needs two contacts though so I don't know why they included more.

The camera has a data back LED to trigger the data back each time the shutter is released. So a data back was planned. This eventually appeared with the FX-103.

Other functions include a flash ready contact in the hot shoe. This works with the Contax TLA20 but I've not checked it with any other flash models. There is no TTL flash. This was introduced with the FX-103.

There is also a self timer switch on the front of the camera which also provides a momentary exposure lock.

There is one thing about the camera I have failed to understand. At the top of the lens mount is a switch which is activated by the lens maximum aperture tab. Normally this tab tells the body the maximum aperture of the lens which it uses for displaying the aperture in use. But the FX-A doesn't display the aperture and, what's more, this is just a switch, not a variable resistance or a digital encoder as is found on other bodies to indicate the aperture. So what this switch was intended for I don't know. It just seems to tell the body that a lens has been attached and no more.

My example of the FX-A appeared recently on ebay. I was lucky. It had only just been put on when I saw it. The buy-it-now button has never been pressed so fast. There was no information other than it was untested so I expected it not to work. But on inspection it powered-up and the lights came on, including the focus indicators, but the shutter wouldn't fire. I also noted the mirror had slipped. Two common problems with Yashica SLRs. Having fixed these problems many times in the past on other Yashica (and Contax) models, I had no hesitation to attempt repairing the camera albeit knowing there would be some differences. The main difference, of course, is the additional modules and circuitry for the focus assist. This has caused the flexible circuit board to be enlarged and increased in complexity which makes removal, required to enable the camera to be dismantled, somewhat more complex and time consuming. Overall I spent nearly two days repairing and servicing the camera. The camera now works as intended and has also had a full service carried out.

The leatherette covers on the camera were perished as usually happens. Strangely, the cover around the grip is rubber and was in perfect order. I've replaced the other covers with some I had and have fitted a rubber thumb grip to the back which I think compliments the front grip quite well.

The focus-assist works well in good light with a contrasty subject. But it becomes less reliable as brightness and contrast reduces. There are no other focus aids in the viewfinder so you either rely on the focus assist or use the matt area of the screen to focus.

The FX-A is now a collectors item. I don't see this as a users camera. It's quirky and interesting to use (once) but will then sit on the shelf I'm sure. I'm not really a collector so if anyone is interested in becoming the owner of this FX-A, make me an offer. It will have to be a good one though.

I've attached a selection of photos taken during the repair for anyone interested in the internals.

Is your mirror staying up?

 I've seen a few discussions about this recently and the suggested reasons and solutions show a lack of understanding of general principles. So here's a few reasons of why a mirror may stay up.

1. Mirror is stuck to the mirror foam.

This is a myth, often repeated but, I imagine, never actually seen. I've never seen it in the hundreds of cameras I've repaired. Even ones with very sticky foam, I've never seen a mirror actually stuck to it. Let's move on.

2. Mirror hits the back of the lens.

If the mirror slips down in the mirror carrier such that the bottom of the mirror overhangs the carrier, it 'might' hit the back of the lens. It depends on how much the mirror has slipped and how far the lens protrudes into the camera. It may happen with some lenses and not with others. It may happen with some lenses only if they are focussed on, or near, infinity as the lens moves further away form the mirror as it is focused closer.

There are two possible scenarios if the mirror hits the back of the lens depending on how high the mirror gets before getting stuck. 

a) If the mirror rises sufficiantly for the shutter to fire, the shutter will open and close normally but the mirror will not fall after the shutter closes. The camera can be cocked again but the mirror will remain up.

b) If the mirror rises insufficiently for the shutter to fire, the shutter will remain cocked and no exposure made. The camera will become locked.

In both cases, the camera works normally if no lens is fitted.

3. Shutter fails to close.

The closing of the shutter triggers the release of the mirror. If the shutter fails to fully close, the return of the mirror doesn't get triggered and it stays up. The camera, usually, can be cocked again and the mirror will typically return back to the down position.

Depending on the camera and the type of shutter, sometimes the shutter can be pushed to make it close fully and the mirror will then fall. Try this at your own risk.

My S2 - it's a keeper

 I bought this S2 a while ago - someone had squirted oil into the shutter and had removed and refitted the focus screen incorrectly which caused other problems. I couldn't save the shutter so it was replaced and various other repairs carried out. The interesting thing (to me anyway) is this example has been converted to have average metering like the S2b instead of spot metering. The mask that defines the spot area has been swapped for the mask that is normally in the S2b. Maybe the masks were swapped between a S2b and this S2 or maybe it was done when spare parts were still available and someone acquired and fitted the S2b mask. However it was done, it suits me as I've never liked the spot metering. So I think this one's a keeper.

The covers I've fitted are some fabric covers I'm experimenting with. Also available in blue and black if anyone is interested.

Shutter speeds - before and after service

An example of the difference a service can make to the shutter speeds of a camera - in this case, an RTS II.

Shutter speeds before service:

Shutter speeds after service:

And, although not the sole reason for the slow shutter speeds, this is the dirt, on the end of a slip of paper, removed from the shutter magnet which can cause the magnet to be slow in releasing the second curtain and cause the shutter speeds to be slow and, often, more erratic.

Replacing the 159 focus screen

The 159 focus screen is not considered user replaceable despite it being fairly easy to remove. The problem is refitting it. In the user manual it says the screen should only be replaced at a service centre and with good reason. If not done correctly the screen will, almost certainly, be damaged. I know, I've done it.

I experimented with an old screen to see if I could find a way the screen could be changed without damaging it. Described here is my method found through that experimentation, it's not a manufacturer recommended way.

Before proceeding a method of holding the screen without damaging it is necessary. Later camera models had screens with a tab to be used to hold the screen by but the 159 screen doesn't have a tab. I use a pair of flat tipped tweezers that have had the tips covered in heat shrink cable insulation. This is permanent and I only use them for this purpose but a temporary solution could be some rubber sleeving fitted over the end of some tweezers.

I also recommend the mirror buffer foam be removed. This makes it easy to see the release catch.

First, the camera needs to held inverted.

A piece of card needs to be cut and bent to fit into the camera such that the edge sits against the back of the focus screen frame (see arrow in next picture). The card will stop the frame jumping out of its retaining slot and will also protect the mirror from possible scratching.

Release the screen by pulling back on the catch. The screen frame will pop up. Lift it up and remove the screen from underneath. This is best done by using something with a point to press against the edge of the screen and lift it up then use the covered tweezers to grab the screen and remove it while holding the frame clear. Don't try and remove the frame first, you will probably scratch the screen while trying to remove the frame.

If you do remove the frame after removing the screen, note it has two tabs on it, a wide one on one side and a narrow one on the other, The wide ones goes to the back, the narrow one to the front.

Refitting is the reverse order to the above. Fit the frame first, hold it clear and fit the screen under it. Note the dull (matte) side of the screen goes towards the prism.

Finally, lower the frame but DO NOT try and press down on it to engage it with the latch.

Use a pair of tweezers to pull the latch back as far as it will go. Use the tweezers against the mirror box frame and make sure the latch is held firmly before going further.

This is the most important part of the process. If the latch isn't held back the frame, which is quite flimsy, will get pushed inwards and will scratch the surface of the screen.

With the latch held back, hold the frame into position then release the latch.

This is not an easy procedure to carry out and requires practice of using two pairs of tweezers and a steady hand.

Contax 50mm f/1.7 AE/MM differences

I've worked on both AE and MM versions of this lens before but have never done a direct comparison of the two. Recently I had reason to work on one of each at the same time so was able to do some direct comparisons of their construction. I thought it was worth recording what I found.

The two samples I compared had serial numbers 6504056 (AE) and 7380543 (MM). The differences noted may not be the same for all AE or all MM lenses.

Plastic/metal

The lens uses metal components for the focusing helical, plastic for the internal block that includes the aperture mechanism and carries the lens elements and a mixture of metal and plastic parts for the focus and aperture controls and front cover and dress ring. This is mostly the same in both lens versions except the focus ring on the MM version is metal but plastic on the AE version. The AE version I had showed why this change was probably made - it had cracks in the plastic around the screws that attach the ring to the focusing mechanism. This had caused the focusing ring to become loose and allowed the focusing helical to separate - which is how I came to have the lens. I have seen some cracks like this before so is clearly a potential issue.

Focus guides

Lenses of this general construction usually have one or more guides that allow the focus helical to move back and forth but stopping it from rotating. If these guides, or the slots they move in, become worn, slop or backlash can appear in the focus mechanism. Many lenses have one of the guides split so that its width can be adjusted to take up any excess. The AE version didn't have a split guide while the MM version did.

The slot in the helical component was also different in cross section which means the guide only contacts the helical at the edges in the MM version. What difference this would make I don't know.

Lens mount

The construction of the lens mount is completely different on these two lenses but I think the mount changed before the MM lenses were introduced so this isn't a AE/MM difference as such. The mount, of course, works in exactly the same way but the parts and their assembly is different.

I guess the question has to be, if the differences are so small, why is one lens suited to MM mode cameras and the other not. There may be other differences between the aperture mechanisms that are not really visible. The small constructional differences I could see between the two assemblies were not worth mentioning but maybe they do have some significance. The basic operation of both look identical.

Edit: I have, of course, passed over the infamous 'ninja star' aperture shape of the AE lenses. This is minimal on the 50/1.7 but it is present and shows the shape of the aperture leaves on the two lenses are different.

A new 139 fault

There's not many faults on the 139 I haven't previously seen but I did find a new one recently. The camera had very inconsistent shutter speeds with variations of up to half a stop in either direction. The shutter speeds are often out of specification, maybe 50% of the time, but I've never before seen a 139 with such variations.

The problem was caused by a contaminated shutter magnet so the solution was quite simple - clean the magnet. It's something I do anyway if I service a 139.

The shutter magnet is not to be confused with the release magnet, which can also become contaminated but the symptoms are different. Here's a picture of the shutter magnet. The white plastic arm has a metal plate at the top which contacts the magnet face. This plate and the magnet face are the parts that need to be cleaned.

The more usual symptom of a contaminated shutter magnet is the shutter staying open due to the plastic arm staying permanently stuck to the magnet.

Strap Lug Replacements Available

Following on from my previous post. I went ahead and had some replacement strap lugs made. These are made from stainless steel so won't wear like the originals did. Made for the 139 but they will also fit the 159, 137, RTS and RTSII.

The lugs can also be supplied if anyone wants to fit them themselves. Please contact me for prices.

Old strap lug. Insert has moved and lug has been badly worn.

New stainless steel strap lug.

Strap lug replacement

The strap lugs on the 139 are made of brass with a steel insert to stop the soft brass being worn away. Unfortunately, the idea doesn't work that well and the steel inserts move and allow the brass to be worn away. Later cameras, such as the RX, have stainless steel lugs which don't wear.

I managed to get a small quantity of the stainless steel ones but have now used them all so am investigating getting some made. I would be interested to hear if anyone would be interested in purchasing replacement lugs (or having them replaced by me) so I can judge the potential use.

Please let me know if this is of interest. Now available. See later post.

An unusual fault

Thought I'd document a fault I saw recently as it's an unusual one.

The symptoms are that, when a manual shutter speed is selected and the camera not cocked, when the shutter release button is pressed, the LED in the viewfinder that indicates the selected shutter speed will come on immediately but the LED showing the shutter speed required will not come on until after a period equal to the selected shutter speed. And if B is selected, it will never come on.

The cause was a faulty transfer switch - the first type which is a sealed micro switch. Normally, when these fail the camera won't release the shutter as the transfer switch goes open circuit and the processor never gets the signal to say the shutter is cocked. In this case, the switch went short circuit so the processor thought the shutter was cocked even though it wasn't. Consequently, the processor would activate the shutter magnet for the selected shutter speed and, for reasons I don't understand but it's probably just part of the programming, the meter is not activated and the LED showing the suggested shutter speed isn't lit.

This is only unusual in the way the transfer switch failed. I've never seen one fail this way before. And, because the camera otherwise worked normally, there was little to indicate what the issue was.

Documents update

I've just added the Yashica FX-D repair manual to my documents page.

One useful item in it is a clear description of how to align the viewfinder LEDs. This is just as relevant to the 139 and as I always end up turning the wrong screw in the wrong direction, I'll be keeping a copy of this somewhere to hand.

Is your 139 locked up? This may help.

The Contax 139 is an electronically controlled mechanical camera. 'Mechanical' in that all the physical operations are driven directly by operating the film advance lever or by springs that are tensioned by the same action. Those springs subsequently drive the mirror up, rotate the shutter main shaft, drive the shutter curtains and return the mirror back to its normal position - in that order. Without any electronic control, all the steps in the sequence will still happen if manually triggered. The electronics just introduce a delay between the release of the first and second curtains by blocking the release of the second curtain with an electro-magnet and so controlling the period the shutter is open for.

Sometimes the sequence might not complete, or maybe fails to start, leaving the camera in a blocked condition where it's not possible to operate the film advance lever and the shutter release does nothing. Here's some tips on identifying where the problem could be and what might be done about it.

The first step is to identify if the sequence has started and, if so, at what point it has stalled. This is done by inspecting the position of the mirror and the shutter curtains. Check if the mirror is up or down. Also check if the shutter is open or closed and, if closed, whether it is still cocked or not. The following two pictures show the shutter in both cocked and released condition looking at the back of the shutter.

Shutter cocked

Shutter released

Possible scenarios:

1. Mirror is down and shutter is still cocked.
The sequence hasn't started. Watch the data back LED located at the bottom left of the shutter (visible in above pictures) and press the shutter release. If the LED flashes, the most likely fault is the release magnet is stuck. The release magnet is a permanent magnet which holds the mirror mechanism in its cocked condition. To release the mirror, an electro-magnet, wound around the permanent magnet and in opposition to it, is energised so cancelling the permanent magnet field and releasing the mechanism. The face of the magnet can become contaminated causing the release lever to stick to it even when the magnetic field is cancelled. The solution is to clean the magnet and release lever faces. There is more information on this on my DIY page. If the data back LED doesn't flash, the release signal is not getting through to the magnet driver circuit. Most likely cause is the transfer switch but there could be other reasons. More investigation is required.

2. Mirror is up and shutter is still cocked.
When the mirror reaches its up position, the mirror mechanism triggers the shutter. See the bottom of the page for a description of the couplings between the mirror mechanism and the shutter. With care, it is possible to manually trigger the shutter.

Triggering shutter

If the shutter triggers, the shutter is not at fault and the problem is with the mirror mechanism. Most likely cause is the lever of the mirror mechanism that contacts the shutter release lever is seized due to corrosion of the snap rings holding the lever onto its pivot. Another possible cause is that the mirror has not moved up far enough to trigger the shutter. This can be caused by the mirror foam being too thick.

Corroded snap rings

If the shutter doesn't release even when manually moving the release lever, there is a fault with the shutter. It's possible something is blocking the shutter, such as a piece of broken film, so it's worth trying to blow any debris out of the shutter with a can of compressed air. Other than that, the shutter needs removing for investigation.

3. Mirror is up and shutter is open.
The first shutter curtain opens immediately the shutter is triggered. The second curtain is held by the shutter magnet. If the second curtain fails to close the magnet may be contaminated and the lever that releases the curtain is stuck to it. This is easy to check visually. See the 'Triggering shutter' picture above. The white plastic lever that is held in position by the magnet is clearly visible. In the picture, the lever is in its released position. If the magnet has released the lever but the second curtain doesn't close, there is a fault with the shutter. See previous scenario.

4. Mirror is up and shutter is closed but not cocked.
In this instance, the first thing to check is if the shutter has fully closed. Compare the shutter with the 'Shutter released' picture above. There may only be a millimetre of difference in the position of the shutter blades but that is enough to cause a problem. If the curtain isn't fully closed, it may be pushed upwards by pushing against one of the rivets. This may close the curtain and release the mirror. If this happens, the problem is likely to be the second curtain brake which can become seized, or very tight, and prevent the curtain from fully closing. There is information on my DIY page about this issue. If the shutter is fully closed but the mirror hasn't returned then the problem is likely to be with the mirror mechanism again as in 2 above.

5. Mirror is down and shutter is not cocked.
The sequence has completed normally.

Mirror box/shutter couplings

These pictures of the shutter and mirror box show the two points of contact between them. The green arrows show the coupling used to trigger the shutter and the red arrows show the coupling used to lower the mirror.

Does your 139 over expose?

If your 139 has never been serviced or had its meter adjusted, chances are it will over expose.

Almost every 139 I've seen has had a degree of over exposure. Usually between a half and one stop but sometimes more. Recently I had a 139 that overexposed by a couple of stops and decided to investigate further. This lead to me discovering that the meter sensor had become cloudy. Checking the sensors in some other cameras I found nearly all of them were cloudy to some extent and this seems to be the reason why 139s generally over expose. Looking closely at the sensors, there is a glass filter fitted over the sensor and the cloudiness is under the glass. It's impossible to remove. The glass filter is very thin and is stuck down and any attempt to remove it results in its destruction. Under the glass is a clear compound - could be silicone or something similar. It seems it's this which is going cloudy.

Here's just three I picked at random from my collection of donor cameras. You'll see two have cracked filters also although I don't think that's a problem.

To compare, here's a clear one.

In a few cameras where the cloudiness has been quite bad, I've replaced the sensors but I only had ones removed from donor cameras and they were also cloudy to some extent. What I needed was a new replacement and, amazingly, I seem to have found one.

The sensor I found is mechanically identical and has the same glass filter on it. The specification says it's sensitive to the visible spectrum with the filter removing an extended sensitivity into the IR region. As I had no specification for the original, the only way to find out if the new sensor was a good replacement was to try it. I removed a sensor from a working camera, having first done some exposure checks, then replaced it with the new one. Repeating the exposure checks gave almost identical results but probably half a stop less exposure which would be about correct as the original sensor I removed was cloudy.

For anyone who wants to replace their own sensor, the replacement I found is part number VTB8440BH from Excelitas Technologies. I bought mine from RS-Online (UK).

Edit: Couldn't resist adding this picture of a sensor removed from a 159. The 159 clearly also suffers the same problem. This one appears to have flowers growing in it and it was over exposing by one stop.

And in case anyone is wondering if the flash meter sensor also has the same problem, it seems it doesn't. The flash meter sensor appears to be the same, or a similar, sensor but there is no filter on it and the ones I've checked are perfectly clear.

UPDATE: It seems the new sensor is now out of production. DigiKey still has stock but it won't last. Buy while you can. 

https://www.digikey.co.uk/en/products/detail/excelitas-technologies/VTB8440BH/5885859

DIY repairs update

Just updated my DIY repairs page with some information regarding reassembly. An area I've generally ignored in the past but I've had a few people contact me with reassembly issues and this covers those issues.

Cleaning rubber covers

Not really applicable to the 139 but from the 159 onwards rubber covers were used on all the Contax SLRs. These often look past their best and, unlike the leatherette covers on earlier models, can't be easily replaced. I've experimented with methods of cleaning them and think I finally have a reasonable solution.

If the rubber is just showing signs of turning light grey or white from age, cleaning with a cloth and some isopropyl alcohol (IPA) will normally bring back the original colour. A toothbrush is useful to get into corners.

If cleaning with IPA doesn't work, or if the surface has become shiny from handling, then I've found scraping the surface is the answer. I use the back edge of a knife - the sort where you break off the blade as it becomes used. While scraping, the surface will become even more white, or maybe brown if there's a lot of dirt as well. This is then cleaned off with IPA. It might need scraping more than once to get the cover completely clean. I've found it's usually easier to remove the cover from the camera first. This allows the edges to be done without risk of scratching the camera.

Here's the front rubber from a 159 being done. I've done half of it to show the effect of scraping.

Below is the rear of the same camera after being fully cleaned. The back previously had a lot of shiny areas from handling.

A caution: Some models had a different type of rubber covering. The only one I'm sure about is the rear door of the Aria. It has a very thin layer of rubber that is not removable and is often worn through so shiny areas are actually the plastic underneath. Don't try this technique on such covers.

Focus screens

As I mentioned in the previous post, the S2 screen needed replacing because it was scratched. Replacement S2 screens can be found but are usually expensive. I did buy a used one from a well known UK dealer but, when I got it, it was also scratched so it went back. They can be found on ebay, usually from Far East sellers, but can be anything up to £60 or more.

The same screen type is used in the Contax 167 and the Aria so finding a broken 167 or Aria might get you a good screen but the cost is likely to be no better.

I investigated a number of other screen types to see if they would fit and, believe it or not, the 139 screen is perfect. Because the 139 screen isn't user replaceable, there's no tab on it so fitting it is a bit more difficult but the size is the same.

One good thing about the S2 is the screen is aligned by its top surface which is the surface which the image is formed on so any slight differences in screen thickness won't affect the focus. Other cameras align the screen using the bottom surface so the thickness has to be correct to get the top surface at the correct distance from the lens.

So if anyone want's a replacement S2 screen, a 139 screen may be the cheapest answer.

S2 Problems

I bought an S2 a few weeks ago from a dealer in Japan who described it as good condition but with a faulty meter. The fault meant it was a fair, though not necessarily cheap, price. I bought it with the view of fixing it and keeping it. On receipt, though, it was obvious there were several other problems with it. A few emails back and forth and the seller agreed my, much reduced, valuation of the camera and gave me a partial refund.

One of the problems was massively slow top shutter speeds. To do anything with the shutter usually means removing it and that means an almost total dismantle of the camera. Here's the camera now.

The shutter (top middle) is not intended to be repaired or adjusted. The manual says shutters come pre-adjusted and gives no information on how to adjust them. I've worked on these shutters before and have discovered the general principles of how to adjust them but the process is more art than science and this one is not cooperating. I might have to find a replacement.

Here's the shutter back in the camera for testing after one of my many attempts to get all the speeds to within specification.

I'll post further news of this adventure in camera repair as it happens.