Topic – Inside a Yashica J-7

This is the first SLR on my desk that I needed to take apart. The slower shutter speeds used to grind to a halt now and then. It took me an afternoon’s work and at three instances I was sure I had destroyed something. But perseverance did the trick and it seemed to work enough afterwards for the test roll presented here. Unfortunately the second curtain sometimes do not accelerate enough to slam into its final position with a speed enough to drop the mirror. Something was hindering it or perhaps just some oil was needed? Anyway it had to go apart again. This time I photographed what I did, so here goes:

We start off with the Yashica J-7 in one piece:

j-7_dis (1)

The first step is to remove the top cover. This was very time consuming as there were no clear indications on what exactly needed to be removed. Much trial and error and light bending resulted in this:

1/ The black light meter hood can be unscrewed in a normal CCW fashion. A thin washer also come off when it is removed.

2/ On top of the cover the knurled knob (for setting ISO/ASA) should be removed. A small plier can be used for this. CCW direction as usual.

j-7_dis (2)

3/ On the back the black meter push-button is unscrewed (CCW). This can be a bit tricky as it is smooth and there is nothing to get a grip on. Try to get a grip with a plier around the silvery metal surrounding it.

j-7_dis (3)

4/ Next the rewind knob is unscrewed. You need to open the back to do this. DO NOT remove the entire pin though! If you do, then you will not be able to open the camera if you accidentally close it! Yes, I have been there. It is clearly overrated!

j-7_dis (4)

5/ The nut around the rewind knob next has to go. Unscrew CCW with a pointy plier.

j-7_dis (5)

6/ Remove the three little screws around the top cover (two from the behind, one to the right of the cover).

7/ The winding lever has a black cap that also can be unscrewed (CCW) and the lever lifted with some care.

8/ There are three small screws holding the shutter speed selector. Loosen them equal amounts and it should be easy to lift off.

When the cover is ready to be lifted all these parts should have been removed:
j-7_dis (6) 9/ We’re in!j-7_dis (7)

10/ Next the delay mechanism lever has to be removed. Pliers again and again CCW. The small round delay starter (the one with the arrow on it) does not have to be removed.

j-7_dis (8)

11/ There is a small metallic sleeve around the axis. This can be lifted or left in place.

j-7_dis (9)

12/ Now carefully lift off the leatherette on each side of the mirror. Four screws are revealed. They should be removed, but carefully!

j-7_dis (10)

13/ The bottom plate is held in place by two screws, remove them.

j-7_dis (11)

14/ The battery cable is desoldered or cut off. There is enough of it to deinsulate and solder together later. The meter on this camera is way off, so the battery is of limited value anyway.

j-7_dis (12)

15/ Lift the front carefully straight up. Under each screw there are a stack of thin copper washers/shims. Each shim is of a different thickness and must be kept under “its” screw. These shims are factory adjusted for keeping the lens parallel to the film plane. This is crucial for the camera!

j-7_dis (13) 16/ Keep track of where the shims go!

j-7_dis (14)

17/ The delay mechanism can now be removed if necessary. There are two screws, one in each end of the mechanism. The upper one is brass yellow, the lower is black. I removed it on my first forage into the camera, now I remove it later for photographs.

j-7_dis (15) 17/ Note: If you only want to make finer adjustments to the shutter speed there is no reason  to disassemble the camera this much. Around the 1/4″ camera mount are two screws with locking glue. The 2 o’clock one can be loosened half a turn and the 9 o’clock one a bit more and then shifted up/down in the picture below. This way the shutter speed can be adjusted. Remember to fasten them, preferably with some glue or nail varnish, to keep them there!

j-7_dis (16) 17/ In the above picture the mirror assembly is held in place with the two brass screws at the bottom of it. There are also two screws with washers reachable from the top of the camera. Unscrew all of these (four in total) and the mirror assembly is loose. It takes some feel for removing the assembly as there are many “signal levers” surrounding it. It is however free and just needs some careful wiggling to come off.

18/ The flash contacts can now be desoldered, or the entire PCB removed with the two black screws in the picture below.

When the assembly is removed the escapement mechanism (main timer module)  is visible. It is held in place by the screws mentioned in (17) above.

j-7_dis (17)

19/ Take some time to study the mirror assembly. The rightmost, in the picture below, lever lifts the mirror. The tappet, pointing up in the middle of the picture, is the mirror release and the backwards-“L”, to the left, signals to the first curtain to start moving. Thus the curtains cannot move unless the mirror is up. I am completely fascinated by all these signal linkages everywhere. It really is very cleverly put together!

j-7_dis (18) 20/ The main timing mechanism (escapement) is at the bottom of the camera. In the back are the curtains. The rightmost vertical roll is the take up spool for the curtain. It is still possible to dry-fire the mechanism when in this state: Pull the winding lever, push down the shutter starter (horizontal “foot” in the uppermost left). Now it is ready for firing off the curtains. The backwards-“L”, mentioned above, normally does this, but as it is now removed we can do it manually by giving the small lever protruding just below and to the right of the chassis screw a nudge. Great fun for everyone!

j-7_dis (19)

21/ Depending on the position of the timer cam, different shutter speeds are selected. The selected shutter speed is relayed down to the escapement by a vertical rod.

j-7_dis (20) 22/ If the slow times are erratic or simply stop, the entire assembly can be removed and dipped into isopropyl alcohol. A few actuations when still wet usually removes any residues in the bearings. It can run dry and does not need to be lubricated.

j-7_dis (21)

23/ The delay assembly can undergo the same treatment if necessary. Here it is shown with its two different coloured screws.

j-7_dis (22)

24/ The timing cam setting to the right is relayed to the exposure meter through a U-shaped link all the way to the left. Cool!

j-7_dis (23)

25/ All bits and pieces removed this far:

j-7_dis (24)

26/ The mirror assembly can now be cleaned. The pentaprism is held in place by two small springs. Removing them reveals the focussing glass. It is easy to slip and scratch the focussing glass at this step. If not dirty (ground glass that is:), do not remove anything. Chances are there will be even more dust after trying to clean it than it was before! I used a small brush for cleaning and that was quite effective. Tissues always leave some particles! You have been warned!

j-7_dis (25)

27/ Reinstalling the mirror assembly is the most time consuming part for me. Do not rush it and make sure the vertical tappet on the wheel below is the indicated position. Slowly pull the winding lever until the wheel is in this position or it will be MUCH more difficult to get the assembly back.

j-7_dis

28/ Well, that’s about it! Reassembly is in backwards order, remember to dry-fire often. Make sure the shutter works in every step. Or, perhaps/likely, you will have to disassemble it again:)

Was this helpful? Or even interesting? Give me a note will you?

Oh, and here are two films showing how to dry-fire it. One without and one with the escapement in place:

http://youtu.be/N0PpENJOGsI

and

http://youtu.be/iUEjMHHyys4

Cheers!

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7 Responses to Topic – Inside a Yashica J-7

  1. Phil Elsham says:

    A great piece of work, not just with the camera, but also the way you’ve shared it with us. Many thanks. Phil

  2. jabcam says:

    Thanks. Hope it can be of some use. AFAIK many cameras share about the same internal mechanics. If I didn’t care about the camera I would take it apart even more. The meter is off, perhaps fixable in the future? But this will do for now.

  3. stillthrill1 says:

    Thanks for letting us look inside!

  4. jabcam says:

    …and you’ll be surprised how many SLRs from the last 50 years look just about the same inside!

  5. Mark says:

    Would you happen to know if the shutter speed selector is the same as on the J-5? I need one for my j-7 but so far have only found a j-5 being sold for parts.

    • jabcam says:

      The J-7 is the only vintage Yashica I have. A guess is that they do not differ all that much but I do not know for certain, sorry.

  6. Aaron says:

    Your work on the J-7 helped me with my Yashica FX-2 with a malfunctioning mirror box. They are stunningly similar with the exceptions of a few nylon/plastic gears in place of the brass ones in the J-7. The rest of the internals look nearly identical. Thank you.

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