Prontor SVS 1 1/2 1/4 really fast!

[Psycholist]

So the Prontor SVS that is in my Weltaflex, or rather is now out of my Weltaflex, is acting odd. From 1/300 to 1/8 the shutter is "in the ballpark." I'm not using a meter, but each speed is noticeably slower than the next and sound comprable to other cameras that I have.

However, 1/4 and slower all operate at or near the maximum speed of the shutter. Something to do with the slow speed mechanism, but what? I guess I'm hoping someone has run across the same problem before and can offer a suggestion if not an actual solution.

Thanks,
Keith

 

[baachitraka]

Its time for CLA. Prontor SVS in my Isolette III was firing at maximum speed for all speeds. I did not worry much about it since, I use it mostly with flash.

 

[shutterfinger]

as stated above, it needs a CLA.
All speeds below 1/100 are based on the delay gear train which is set for 1 second and may have a secondary setting for 1/15 or 1/25. The slowest speeds depend on the delay mechanism operating its full travel. Fast slow speeds are due to the delay not setting or not going to its travel limit.
Although faster speeds may sound good they are most likely off by 1/2 stop or more.
1/100 - 1/125 is the speed the main cocking spring will operate the shutter blades with the delay locked out. Speeds above 1/125 are achieved by adding booster spring tension to the blade closing.

 

[Psycholist]

Thanks for the replies. Of course a cla is always a good idea with an old crusty camera, and a bath in lighter fluid did bring my self-timer back to life, but it didn't help the issue with 1, 1/2, and 1/4 seconds.

I've taken someone else's images of the mechanism and made some marks on them to discribe what is happening.



The tab (orange circle in the picture of the escapement) should move into the notch (orange circle in the image of the "cam") in the direction of the green arrows when set to the speeds noted above. It will not do this on its own though. If I cock the shutter and it is in timer mode, I have time to place light pressure on this tab when the shutter fires. When I do this, voila, the tab goes where it should and I get a resonable facsimilie of whichever of those speeds I've chosen.

Unfortunately it only does this when I push on it. Which leads me to believe that there's a spring either missing, broken, or not engaged with something.

Any chance someone knows this shutter well enough to tell me where to start my search?

Thanks,
Keith

 

[shutterfinger]

Well, that shade tree, corner cutting lighter fluid bath did not or will not clean the gunk out to where the delay mechanism will work properly and the oily residue it leaves behind isn't helping matters either.
1. get some CRC QD Electronic Contact Cleaner http://www.oreillyauto.com/site/c/d...ap?ck=Search_N0439_-1_2743&pt=N0439&ppt=C0090 , put the delay assembly in a small glass jar, spray the contact cleaner in the jar until the delay assembly is covered then put the lid on the jar and snug it. You can use the straw and spray the cleaner into the mechanism as you fill the jar enough also. Swish it around and let sit for a half hour or so. Check operation for smooth operation of all levers and gears.
2. get some lacquer thinner and soak the mechanism in it for a half hour or so. Lacquer thinner will dissolve any plastic or rubber part or coating and will strip bluing from shutter and aperture blades. It may strip the paint off the shutter case. Use with caution.

Once thoroughly clean put a trace of oil on the gear shafts ends and lever pivots. A drop the size of a straight pin point is all that is needed, more will act like glue. Use clock oil, gun oil, TriFlow or similar oil. Do not use 3in1 oil or Water Dispersant #40.

If this does not solve the problem then the delay assembly will have to be disassembled, all components wiped clean, and reassembled. The lever at the orange circle must float on its shaft. The oil in the lighter fluid residue is enough to gum it up.

 

[Psycholist]

Well, it seems I have inadvertently stumbled into the "bike helmet" issue of the camera world. An issue filled with vitriol.

baachitraka, your reply was cheerful and I take it in the spirit given.

Shutterfinger, I'll be honest, I stopped reading your second response after it became rude, condescending and insulting. That was before the end of the first sentence.

I'd asked a specific question. Essentially, "Shutter Y is doing X. Does anyone know what causes X in Y shutter?" The answer I got was "needs a CLA." That is the sort of answer that is technically accurate, but functionally useless. It would be like going to a motorcycle forum and asking "My vintage motorcycle is gradually developing a miss at high rpms," and getting the reply "D@#n thing's broke."


--------
For anyone who might stumble across this thread in the future, here's the correct answer.
Q. My Prontor SVS seems to work correctly at all speeds except 1, 1/2, and 1/4. Those speed are exceptionally fast.
A. The low speed mechanism is not engaging. One possible cause is that the low speed pallet (who's tab is circle in orange) is not pivoting into position. The pivot point (orange arrow) may merely need cleaning. However in this particular case the pivot shaft was so rusty that it was pitted. Removal and polishing of the shaft did return some motion, but a replacement will ultimately need to be sourced.



Do keep in mind that there are several versions of the SVS, so I can only state with certainty that it applies to those shutters who's cams look like the one pictured in my previous post and have speeds B,1,2,4,8,15,30,60,125,300. The low speed mechanism is only involved in 1,2,and 4. A mid speed pallet (red circle) is used for 8,15, and 30. Neither are involved in 60,125 or 300.
--------


Woe unto me for using lighter fluid. I'll ignore the fact that it brought the delay timer back to life and had no detrimental impact on the parts that were already working. The issue it didn't fix would not have been fixed by any solvent, but nonetheless. From now on I'll only use proprietary White Magic solvent at $50k per microliter to clean and Unicorn spleen oil as a lubricant.

Seems to be a lot of people who either act like shutters are magic, or worse yet, machines that are so complex only an anointed few could ever hope to understand, let alone work on them.


Mechanical shutters are just machines. Fairly simple ones at that. Springs, gear and levers; and that's it. Anyone with a steady hand and a rudimentary understanding of mechanics can fix one. I'd come here looking for enough info to avoid disassembling the entire thing, which I did not get.

 

[benjiboy]

Well, it seems I have inadvertently stumbled into the "bike helmet" issue of the camera world. An issue filled with vitriol.

baachitraka, your reply was cheerful and I take it in the spirit given.

Shutterfinger, I'll be honest, I stopped reading your second response after it became rude, condescending and insulting. That was before the end of the first sentence.

I'd asked a specific question. Essentially, "Shutter Y is doing X. Does anyone know what causes X in Y shutter?" The answer I got was "needs a CLA." That is the sort of answer that is technically accurate, but functionally useless. It would be like going to a motorcycle forum and asking "My vintage motorcycle is gradually developing a miss at high rpms," and getting the reply "D@#n thing's broke."


--------zero
For anyone who might stumble across this thread in the future, here's the correct answer.
Q. My Prontor SVS seems to work correctly at all speeds except 1, 1/2, and 1/4. Those speed are exceptionally fast.
A. The low speed mechanism is not engaging. One possible cause is that the low speed pallet (who's tab is circle in orange) is not pivoting into position. The pivot point (orange arrow) may merely need cleaning. However in this particular case the pivot shaft was so rusty that it was pitted. Removal and polishing of the shaft did return some motion, but a replacement will ultimately need to be sourced.

View attachment 81382

Do keep in mind that there are several versions of the SVS, so I can only state with certainty that it applies to those shutters who's cams look like the one pictured in my previous post and have speeds B,1,2,4,8,15,30,60,125,300. The low speed mechanism is only involved in 1,2,and 4. A mid speed pallet (red circle) is used for 8,15, and 30. Neither are involved in 60,125 or 300.
--------


Woe unto me for using lighter fluid. I'll ignore the fact that it brought the delay timer back to life and had no detrimental impact on the parts that were already working. The issue it didn't fix would not have been fixed by any solvent, but nonetheless. From now on I'll only use proprietary White Magic solvent at $50k per microliter to clean and Unicorn spleen oil as a lubricant.

Seems to be a lot of people who either act like shutters are magic, or worse yet, machines that are so complex only an anointed few could ever hope to understand, let alone work on them.


Mechanical shutters are just machines. Fairly simple ones at that. Springs, gear and levers; and that's it. Anyone with a steady hand and a rudimentary understanding of mechanics can fix one. I'd come here looking for enough info to avoid disassembling the entire thing, which I did not get.

At least we have the sense not expect to get free service advice about our cameras on an internet forum, and insult
the members who reply for telling you what they really think.

 

[shutterfinger]

Two links that may be of help:
http://benoit.suaudeau.perso.neuf.fr/manuels_rep/obturateurs/001_pdfsam_prontor.pdf
http://www.rolandandcaroline.co.uk/repair/prontors1.html

the delay mechanism in Prontor and Compur shutters are wrist watch type mechanisms employing a spiral torsion spring not a straight arm torsion spring as most shutters do. these type shutters require a more refined service technique than the conventional ones.

 

[BrianShaw]

...
Shutterfinger, I'll be honest, I stopped reading your second response after it became rude, condescending and insulting. That was before the end of the first sentence.
...
I'd come here looking for enough info to avoid disassembling the entire thing, which I did not get.

While I don't agree with his assertion that lighter fluid leaves behind oily residue, there is a lot of truth to what he says and he was being factual rather than rude. Just like clocks and watches, shutters really need to be disassembled to ensure that all parts are properly cleaned. And to be properly lubricated, they need to be disassembled also. Even talented people ruin the first shutter or two when they try to home repair them. if you can accept that risk the go for it. If not...

 

[BrianShaw]

p.s. Welcome to the forum.