Zenzanon S 80 mm lens shutter irregular

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Cor

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(long time member, mostly lurking though)

So I have this nice Zenza Bronica 6*6 SQ for 30 plus years bought together with a Zenzanon S 80 mm lens . In later years acquired PS 50mm , 150 mm & PS 250mm Zenzanon lenses. Always been happy, everything functioning flawless.

Until this weekend when the S 80mm started to behave odd. It would not fire at the wanted speed (say 1 sec) only at the default 1/500 sec. Not all the time though, roughly 1 out of 10 correct, the rest at 1/500. The problem is with the S 80mm , all my other PS lenses behave perfectly.

Cleaned the contacts (looked fine anyway), even looked inside to check the soldering to the shutter, but my inexperienced eyes could not see a problem there either.

Any suggestions solving this problem, other than trying to get it repaired here in the Netherlands ?

Thanks for any feedback,

Best,

Cor
 

DWThomas

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#1 Do the other lenses work on that body?
The camera defaults to 1/500 with a dead battery, but in that case, all lenses should show the problem.

If other lenses work it could mean a connection has broken in the lens -- or -- there is something unhappy with the shutter.

As I understand it, those shutters are fired mechanically but the electrical functions control the timing; presumably by catching the shutter open and releasing it via a solenoid which in this case could be open circuited or mechanically jammed.

(I own an SQ-A and a bunch of PS lenses but so far have escaped the symptoms you describe so can't offer much more.)
 
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Cor

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Thanks for the reply, yes my other lenses work perfectly, so it is really the S 80mm. As I also understand from an file I found: the default of the Seiko shutter is 1/500 sec. There is an electromagnet slowing down the shutter by slowing down the closing of the shutter. somewhere in this system I assume the magnet does not function. Sometimes it does work, most of the times it doesn't.

But how to fix it ?

Best,

Cor
 

koraks

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@Cor good to see you around. We should meet up once again. Sorry for taking so long to reach out again.

I've had a look at the pdf that you were pointed at before: https://ianbfoto.com/downloads/Repairs/Anatomy of Seiko 0 shutter used on ZENZANON lenses.pdf
In particular, page 20 seems relevant. This points in the direction of the solenoid which may not become energized for some reason.

There is an electromagnet slowing down the shutter by slowing down the closing of the shutter. somewhere in this system I assume the magnet does not function. Sometimes it does work, most of the times it doesn't.

But how to fix it ?

Indeed; although I'd formulate it a little differently. Apparently, the shutter opens and in normal (A) mode and all times slower than 1/500 the solenoid is energized. It remains energized until the shutter needs to close, at which point power to the solenoid is cut.

So I'd start by measuring continuity on the solenoid and all tracks and contacts that involve this solenoid. The wiring diagram on page 24 of the pdf should be useful for this.
 
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Cor

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We indeed should !

Electronics are outside my comfort zone I am afraid though...😆... let's see if there is a mechanical solution (though I also think it is in the electronics..)..

see you,

Cor
 

DWThomas

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koraks

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Thanks for that link!

Credits for digging it up go 'Peerke' on the Dutch analog photo forum who posted it: https://www.analoogfotoforum.nl/index.php/topic,33900.msg371757.html#msg371757

We indeed should !

Electronics are outside my comfort zone I am afraid though

Feel free to drop by and bring it; I'd be happy to have a look. If it gets too complicated (there's a good chance it will), we can always put it back together. I'd be happy to make you a coffee and some lunch!
 

reddesert

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Thanks for that link! I had an earlier version of his site bookmarked where he had a article on opening up a Zenzanon lens, but last I tried, the URL no longer worked. I downloaded this one in case of future need (although my aging, increasingly shaky self might not be able to do it).

FYI, that article was originally written by Max Vettore and posted on his site buonaluce.com, which no longer exists, but you can find his articles on Bronica lenses and shutters by going to the Internet Archive and searching for buonaluce.com, e.g. https://web.archive.org/web/20160109153958/http://buonaluce.com/
 

DWThomas

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FYI, that article was originally written by Max Vettore and posted on his site buonaluce.com, which no longer exists, but you can find his articles on Bronica lenses and shutters by going to the Internet Archive and searching for buonaluce.com, e.g. https://web.archive.org/web/20160109153958/http://buonaluce.com/
Thanks, yes years ago I had downloaded the article on the lens 'just in case' but I wanted to pass some info to another party and tend to be reluctant about sticking someone else's writings on my own site. I guess I haven't looked in a while, but years back the archive sites tended to strip out pictures and poof, there goes a thousand words at a crack! 🙂
 

Dan Daniel

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Well, no experience of these shutters directly. But I will say, that the intermittent firing sounds like a bad mechanical connection. I would look at whatever in the lens creates the connection to the body. If there is any mechanical aspect of its function- spring pressure or such- clean it, maybe lubricate it. Maybe the connection part needs to be ever so slightly bent out to the body connection. Etc. etc. Check both the shutter speed signal to the body and the ground circuit. Just a thought. And the solenoid itself might need cleaning.
 

DWThomas

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Well, no experience of these shutters directly. But I will say, that the intermittent firing sounds like a bad mechanical connection. I would look at whatever in the lens creates the connection to the body. If there is any mechanical aspect of its function- spring pressure or such- clean it, maybe lubricate it. Maybe the connection part needs to be ever so slightly bent out to the body connection. Etc. etc. Check both the shutter speed signal to the body and the ground circuit. Just a thought. And the solenoid itself might need cleaning.
Yes, I note in that latest PDF file showing the printed circuit board and such there is a set of contact leaf springs. Those are prime candidates for dirt and oxidation. And of course the S series Zenzanons are potentially much older than the PS series.
 

wiltw

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Well, no experience of these shutters directly. But I will say, that the intermittent firing sounds like a bad mechanical connection. I would look at whatever in the lens creates the connection to the body. If there is any mechanical aspect of its function- spring pressure or such- clean it, maybe lubricate it. Maybe the connection part needs to be ever so slightly bent out to the body connection. Etc. etc. Check both the shutter speed signal to the body and the ground circuit. Just a thought. And the solenoid itself might need cleaning.

As already described, the Seiko shutter is MECHANICALLY actuated to OPEN by a swinging arm actuated by the body, and electrically truggered to close (for shutter speeds slower than 1/500) by the timing circuit in the body via the electrical contacts.
 

reddesert

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You mentioned cleaning the contacts, which is good, but I would also look at it again. When I hear about an electrical circuit that functions some of the time, I think about electro-mechanical problems.

The body supplies voltage through the pins at rear to hold open the shutter for longer times. The body contacts are spring-loaded and should contact the top surfaces of the pins that stick out of the back of the lens (not the ends of the pins). Unfortunately, I don't think there's an easy way to test for good contact while you have the lens on the body, but check to make sure the tops of the pins are clean, none of the pins are bent, and all of the body contacts are protruding the proper amount. Also make sure that there isn't any wiggle in the lens mount. You can try grabbing the lens and wiggling it, if there is any slop, to see if that influences the shutter behavior.
 
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Cor

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You mentioned cleaning the contacts, which is good, but I would also look at it again. When I hear about an electrical circuit that functions some of the time, I think about electro-mechanical problems.

The body supplies voltage through the pins at rear to hold open the shutter for longer times. The body contacts are spring-loaded and should contact the top surfaces of the pins that stick out of the back of the lens (not the ends of the pins). Unfortunately, I don't think there's an easy way to test for good contact while you have the lens on the body, but check to make sure the tops of the pins are clean, none of the pins are bent, and all of the body contacts are protruding the proper amount. Also make sure that there isn't any wiggle in the lens mount. You can try grabbing the lens and wiggling it, if there is any slop, to see if that influences the shutter behavior.

Thanks. I pretty much rule the body out, since my other (PS) lenses work perfectly. My older 80 mm S lens still looks like new, it hasn't been used extensively, and I try to be careful with my lenses. The pins look perfect, the lens attaches as it should, no wiggle room. Roughly 1 out of 10 times it fires correctly, does not seem a mechanical problem and indeed an electronic (connection?) one.

On a related note: P (and PS) lenses have this A/T switch: for T(imed) exposure you switch to T (see second post here: https://www.photo.net/forums/topic/520692-bronica-zenzanon-s-lens-8028-a-t-switch/ )
So switching to T and firing the shutter will open the shutter, closing is by moving the switch to "A" again (a bit awkward). This function does work on the 80 S

Is this function battery driven (ie is the solenoid keeping the shutter open ?) or mechnical ?

Best,

Cor

Ps just realized it is an easy test: when the shutter is on T remove the battery and see what happens..duh...
 

koraks

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The pins look perfect, the lens attaches as it should, no wiggle room.

Concerning those 'pogo' pins: the contact issue can also be at the other end, i.e. where they connect with the circuitry inside the lens. Since the pins are spring-loaded, the actual moving contact is inside the lens barrel. It would seem to be that it's especially this contact that is prone to fouling. Maybe see if you can access that side of the pins?

Is this function battery driven (ie is the solenoid keeping the shutter open ?)

No, the purpose of this function is actually to do timed exposures without draining the battery.
If this function works properly on your lens (i.e. it closes at the right moment if it's in T mode), this is further evidence that the solenoid and its attached circuitry is the problem. If the problem also occurs with the lens in T mode (i.e. it always fires at 1/500), it would be a mechanical problem (I think) and you should have a better clue in which direction to look.
 
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Cor

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Concerning those 'pogo' pins: the contact issue can also be at the other end, i.e. where they connect with the circuitry inside the lens. Since the pins are spring-loaded, the actual moving contact is inside the lens barrel. It would seem to be that it's especially this contact that is prone to fouling. Maybe see if you can access that side of the pins?
No sure if these pins are spring-loaded on the lens, will check tonight.

I used: https://web.archive.org/web/20160128034226/http://www.buonaluce.com/Slens.pdf

And I opened up the back of the lens (see PIC 12), don't know if there are springs behind the pins (pins are on the back of the black plastic circle on the left, you see the soldering on the flexible PCB)

Best,

Cor
 

koraks

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don't know if there are springs behind the pins (pins are on the back of the black plastic circle on the left, you see the soldering on the flexible PCB)

I expect these to be spring-loaded, yes. But see if you can confirm this.
I'm not so concerned about the soldering, although I've had solder joints that looked fine at first glance malfunction (in a lens, coincidentally!) My concern is mostly with the part that faces the camera body, so the underside of the flat-cable where the solder contacts are.
I'd suggest tracing especially the orange wire and whichever one forms the other side of the solenoid circuit, and test continuity from the lens mount pins all the way to the solenoid.
 
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Cor

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Wow, thanks a lot, super instructive, if I dare to go there, don't know yet, have to watch it 5 more times at least I guess..;-)

Best,

Cor
 
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reddesert

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The pins on the lens are not spring-loaded, they are fixed in place.

Even though the body works with other lenses, I'm suggesting that you check the body contacts because the contact is a matter of tolerances. The body contacts only move by a small amount. So if one body contact is a little bit out of position and one lens pin is a bit out, that particular connection could be intermittent. It's probably not the issue, but it is easy to check.

T mode should work without a battery installed at all - you can fire the camera without the battery. (This is true of an SQ, maybe not of an SQ-Ai.)
 
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Cor

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The pins on the lens are not spring-loaded, they are fixed in place.

Even though the body works with other lenses, I'm suggesting that you check the body contacts because the contact is a matter of tolerances. The body contacts only move by a small amount. So if one body contact is a little bit out of position and one lens pin is a bit out, that particular connection could be intermittent. It's probably not the issue, but it is easy to check.

T mode should work without a battery installed at all - you can fire the camera without the battery. (This is true of an SQ, maybe not of an SQ-Ai.)

Checked my SQ and the 80 mm P last night, and it is as you say, pins are fixed, the body contacts ( small golden ball bearings) are spring loaded, by eye I cannot see any problems with pins and body contacts, maybe I have check with calipers. The T indeed works without battery.

Cor
 

dizot

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Here is a video that shows how to fix the solenoid:


Thanks for posting this. I've got a PG 100mm with a shutter that won't close reliably. All other camera functions are operating properly, and my 150mm works perfectly.

This video indicates that the solenoid magnet may have become demagnetized over time. If the permanent magnet has weakened, the mechanism may not be able to pull the shutter closed properly. That makes sense. I hope it is the case, as it should be a relatively straight-forward fix.
 
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