SRT Shutter Tuneup Notes

Disclaimer

I will not be held responsible for any damage that results from you looking at or following these notes. If you don't feel comfortable goofing around with this stuff or the possibility that you could damage something on your camera, just don't do it.

deep inside the srt101
Deep inside my SRT101, note the shutter curtain spring shafts.  The hole I drilled for lubricating one of these shafts can clearly be seen at the arrow head.

First Clean and Lube your Shutter

It is best that you clean and lube your shutter prior to adjusting it. If you don't, you may be putting excess tension on the springs that operate your shutter, in order to overcome friction to achieve proper shutter speed. This is not a trivial task on a Minolta SRT cameras, as the viewfinder and mirror box must be removed to access the cylinders that contain the SRT shutter springs. I have exchanged some emails on the subject with veteran camera repairman Vincent Fairbrother who reports on how to actually lube the shutter springs that are enclosed in hollow cylinders.

"Mike, One of the problems in repairing an SRT, is that commonly the shutter curtain springs are simply dried out and there is no way to get lube inside of the tubes they are in. I have found a simple method which Minolta will never say anything about in their service manual, because they were not servicing cameras that were nearly 35 years old. Take a very fine drill(080, or 1 mm) and put it in a pin vise. Dip it into a bit of oil, and carefully drill a hole by hand in the center part of both tubes, being careful to recover the chips, and not puncture too deeply, damaging the springs. Then with a hypodermic filled with oil, lube those babies, and if you have some compressed air blow into the holes to spread the oil over the springs(Be generous with the oil.) When things start working properly again, fill and seal the holes with some wax from one of those furniture/appliance touch-up sticks to prevent the oil from running out, and then clean up the area with your choice of solvent(Napha). This is a more permanent solution to most shutters that lack enough oomph to fully trip themselves, rather than adding too much tension on unlubricated springs. This trick can be used on almost any focal plane shutter that uses those type of sealed barrels to contain the curtain springs. Good Luck!!! "

Vincent reports that he learned this technique from an elderly Japanese technician from the Nikon factory in Tokyo while he was working for Ehrenreich Photo Optical way back in 1964.

I have now tried this on one junk camera, that I bought expressly for the purpose.   At this point, I'm unsure of the results.  In any case, don't use too much oil, as it will come out the ends of the shaft and end up everywhere inside your camera.  Also drilling a hole in the first shutter, was a bit of a challenge for me.  I ended up drilling right through the curtain, although now that I think about it, you may be able to avoid this by simply releasing the spring, though I didn't think about it at the time.

If the winding mechanism seems smooth, and lubrication of the shutter gears on top of the camera helps get the speeds back into shape, I would leave well enough alone.  Overall, this is an involved task that should be appoached with caution by novice camera repair people.   If you do decide to try this, you can get hyperdermic needles from Micro-Tools for only a few bucks.  For the 25 gauge size, use a number 76 or 77 sized drill bit.  You should be able to get these small drills and  drill bits at most hobby stores.

Shutter and Winding Gear lubrication

I spent a considerable amount of time with that same camera,  trying to get the winding mechanism to work smoothly.  Cleaning with large amounts of Naptha did nothing, although when the Naptha was in place, it smoothed out a bit.   Eventually the Naptha would evaporate and the winding mechanism would become unbelievably hard to work.   No amount of light oil (Nyoil) had any significant effect.  Eventually I resorted to using small amounts of a fairly light grease intended for racing bicyles bearings and things smoothed out considerably.  It's still not as smooth as my other SRT's.  I kept this grease away from the the slow speed timing mechanism.  If anyone has any better suggestions, I'm open to try them.

Next, Adjust Shutter Timing

Once lubed, adjusting the shutter speeds of your SRT is not that difficult if you are used to tinkering with small mechanical devices and take your time. You must have a shutter speed tester that can measure exposure times as well as shutter speed of focal plane shutters. Also you should obtain a copy of a SRT service manual.

Tune It Up



Figure 1. 1st and 2nd shutter tension adjustment gears

Here are the instructions in the srt service manual with my notes. I believe that perfection is not possible and not necessary. For instance it appears that the speed of the 2nd shutter curtain varies depending upon whether the 1st shutter curtain is moving at the same time as the 2nd shutter curtain or not.

shutter_capture
figure 2. Shutter speed adjustment screw locations

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