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Chrisb
Tinkerer
Username: Chrisb
Post Number: 26
Registered: 01-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 22, 2013 - 04:01 pm: | 
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I solved the problem I was having under the top cover with the meter coupling, and thought all I had left to deal with was cleaning the slow speeds escapement. Of course, it's never that easy . . .
First, careful applications of solvent followed by repeated tripping of the shutter while blowing it out, haven't done any good. The shutter still takes about 1.3 secs when set at 1. So I'm wondering if my chances will improve significantly by removing the escapement. The indicators are that its removal is simple enough, but are there any hidden pitfalls? Any linkages or alignments I need to be aware of or make index marks for, so I can get everything properly back together?
Second, I initially thought that this was the root of the shutter/mirror issue, but it's now clear that this is a common problem with these cameras and may well be unrelated. I have tried the drop-of-oil-on-the-mirror-return-firing-gear trick, and it gave no result.
My next step was to crank up the 2nd curtain tension, which I've done in three stages going a notch or two at a time. So at this point I've gone 5 notches and don't want to go any further without outside input. Several dozen firings of the shutter give about 50% success rate (i.e. firing the shutter gives a complete cycle) at 1/1000th, but at 1 sec the mirror rarely returns.
So I'm hoping I can get some input from people about what I've laid out above. I also have a number of questions:
-I've noticed that when the first curtain fires, it never fully disappears. The metal edge piece always protrudes into the film gate. Is this how it's supposed to be? Or should it be disappearing completely into the slot? If it is supposed to 'disappear', what's the remedy?
-When the slow speeds are ticking off, I can see that the mirror return firing gear is turning, so it seems to be driven by the slow speed escapement even though the real motive force for tripping the mirror return lever comes from the second curtain, as far as I can tell. Is it possible that this linkage, or some other linkage (if there are any) is what's causing the slow speeds to run long?
-There is a kind of screeching noise when firing the shutter at slow speeds ( assume I'd hear it at higher speeds too, if the cycle wasn't so fast). I hear it almost every time the first curtain fires, and occasionally when the second curtain fires as well. Is this a sign of dried out springs, or perhaps a need of oil at the points where the shafts are seated? Or something else?
-And finally, when the second curtain fails to trip the mirror, if I go ahead and give the mirror release lever that final push, I'm rather surprised by the resistance it offers. It hardly requires "grunting force", it just seems far less delicately balanced than I would have thought. Is this adjustable? Or perhaps a little lube at specific points is called for?
I apologize for the length and all the questions. Any help would be greatly appreciated. |
Arfd
Tinkerer
Username: Arfd
Post Number: 19
Registered: 01-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 22, 2013 - 05:28 pm: |
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There is more than can be answered in a simple reply. The SRT101 factory manual is available for free on a few sites.
Removing the slow speeds escapement is not necessary and can sometimes cause more problems trying to get it back in if other modules aren't also removed!
The edge of the first curtain being visible could indicate the curtain brake may need adjusting.
The screeching noise almost certainly is due to dry spindle bearings. They can be accessed for cleaning and lubing after removal of the battery holder, 3 screws. Don't expect an immediate improvement, it will take a while for even thin oil to get where it needs to be.
The 2nd curtain always requires more tension than the 1st, at least 1/2 a turn more.
A drop of oil under the bearing of the mirror kick gear is advisable, but not on the plastic gear itself! It is difficult to do properly, try holding the camera upside down. Jon Goodman (of interslice) has a page somewheres devoted to this problem. |
Chrisb
Tinkerer
Username: Chrisb
Post Number: 28
Registered: 01-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 22, 2013 - 06:18 pm: |
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Thanks for your input.
I have already downloaded the manual from the iespana website (the only one I know of besides the very basic pdf offered here on this site). Is this really the factory manual (The drawings are excellent but there is no diagnostic info of any sort, strictly assembly/disassembly without any details relating to specs/tolerances)?
The only visual guide that I have found to the mirror kick gear problem, is Mike's SRT Repairs Page http://www.willegal.net/photo/srt/srt-repairs.htm. The pic provided there is claimed to be courtesy of Jon Goodman. I have seen it referenced very often, and many claiming success after following it.
Note that I didn't oil the teeth of the gear. Rather, I applied a drop of oil at the joint/seam formed by the retaining screw and the face of the gear. Are you saying that this is not what I sould have done?
Can you offer any guidance on the curtain brake? How is this adjusted?
Thanks again for your advice. |
Chrisb
Tinkerer
Username: Chrisb
Post Number: 29
Registered: 01-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 22, 2013 - 08:04 pm: |
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Arfd, thank you so much.
Your recommendation of lubing the spindle bearings was invaluable. A small drop of oil on each resulted in an immediate improvement, with the mirror returning as it should on the fast speeds and B. I even dialed the second curtain tension back a couple notches from the 5 notches that I had added earlier (though I'm getting a few fails now--less than 10%--so I may add that extra tension again if there is no further improvement).
Also, now, when the first curtain opens, the metal edge piece no longer projects as far into the film gate. Previously, almost the entire width was visible, whereas now only about 1/3 is. When the seccond curtain closes, only the merest edge is visible.
The slow speeds still do not work right, though. The second curtain does not fully close and the mirror does not return, and the curtain edge piece remains fully visible in the film gate. The actual speeds have not gotten any faster either (i.e. still slow by about 1/3 stop). I'm trying to make sense of this, how it could be connected to the second curtain/mirror issue. If indeed the two are connected. |
Arfd
Tinkerer
Username: Arfd
Post Number: 20
Registered: 01-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 23, 2013 - 02:40 pm: |
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Pleased you are having some success. You should get away without having to adjust the curtain brake. It is accessed by the circular hole near the shutter spindles, and requires a long forked screwdriver. Best left alone if possible.
I obtained the factory manual for a reasonable price off lensinc.net, it is almost identical with the free one but is more up to date and has a full list of part numbers.
I couldn't find the link to Jon Goodman's repair pages. The nylon kick gear is driven by a small brass gear that is connected to the 2nd curtain take-up roller. The bearing of that shaft is most in need of a spot of oil. Using a small bent screwdriver apply a drop oil to the base of the shaft, (not the ratchet!!), it's not visible, you have to guess. Set the speed to 1 sec and do a few releases. The mirror may stick up, but should come right as the oil moves to where it's needed. If after about 10 releases the mirror is still sticking, apply a drop of lighter fluid to the bearing. That should thin the oil and restore mirror action. Leave overnight to see if more lube is needed.
The shutter should now operate with a reassuring clunk without squeaks or fading sounds. Once the kick gear is OK you may have to go back and relube or dilute the oil on the spindle bearings.
Don't over tension the take-up rollers. I found that once any slack is taken up the 2nd curtain only required about 2 full turns of the ratchet.
A digital shutter tester is useful but the so-called leica drum tester is hard to beat as it gives a complete view of shutter performance over its full travel and any curtain imbalance is easy to spot. www.skgrimes.com/library/old-news/the-leica-drum-shutter-tester
PS the 1 sec time has an adjustment screw on the slow speeds escapement. |
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