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11-30-2012, 01:00 AM   #1
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SV Pentax shutter capping & tension

I have two SVs.
First Question: On the first, the shutter was not closing at low speeds, and in the process of lubricating the underside, I inadvertently released the two shutter tension ratchets. What could I do but slowly re-tighten until the shutters went right across the frame at 1 second. I held up the camera to the light, looking at the shutter curtains, and was able to see a circular flash even at 1000 sec. I tried only to tighten to the minimum that pulled the curtains across, but my question is will this have any affect on the speeds (opening slit) if I didn't do it the right way. Tomorrow I pick up a test film for this camera, so that will give me the results, but regardless, I wish to learn more about what I did.

Second Question: Just taken delivery of the second SV in question, and noticed the red "cocked and loaded" window remained red even after firing. I checked further and looking through the curtains as the shutters fired, I was able to see the round light flash up to 250 second. At 500 and 1000 the window remained black. Capping I wondered, and tried gentle lubrication on all exposed cogs to no avail. The question here is about what you can tell me regarding adjusting for capping, and speed (slit width). Be warned I know next to nothing about this stuff, and have just basic tools. There is a limit to my dismantling ability. Sending out for repair is a standard $220 in Australia and about $150 sending it to NZ. Mail costs to the USA return is $90.

Any information would be appreciated. Thank you, Arnold

11-30-2012, 06:43 AM - 1 Like   #2
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The travel speeds are typically off on unserviced SVs because of lubricants drying. The correct lubricant and amount in the shutter bearings provides a consistent "damping" when done properly to keep the speeds uniform. The residue left by the old lubricant really should be cleaned out completely before re-oiling, and the oil used must be the right (thin) weight to do this properly.
The shutter bearings are at the top and bottom of all the curtain shafts. Typically removing the front plate (lens mount) and mirror box is needed to get good access.
You can really mess up the camera getting either oil or solvents in the wrong place - especially on the curtains or ribbons, or the glue that holds them.
With the camera stripped to access the curtains in-place, it's usually possible to drip small amounts of naptha (lighter fluid) on the bearings to clean the old lube, as long as the camera is held so it only flows through the bearing, and you blow off the excess immediately. Then a needle oiler can add a tiny drop after it dries.
The curtain tension should be set for a certain "transit time" for each curtain to move across the frame. Normally each curtain is adjusted (leading first) using a shutter tester than times it on both sides of the frame; with the second adjusted to give a constant slit-width across the frame so it matches the first.
A shutter tester to do this is expensive, but it's possible to use an old CRT analog TV to approximate it. Looking through the shutter at the screen with the camera horizontal, at high speeds you will see a diagonal slash of light from the image on the CRT. The slope of the slash varies with the curtain travel time, and the width of the slash with the shutter speed. Constant width at 1/1000 shows the curtain speeds are matched. I've had good luck adjusting shutters this way for years, but if you do this without first cleaning out the old lubes you will be trying to compensate for too much drag, and all bets are off.
The Asahi SV service manual is available on the Web, and is worth getting. They are intended for trained camera techs, so a basic camera repair text is also a good idea. National Camera in the US still has their course manuals available (mail order) that talk you through full strip-down and reassembly of a K1000 - which of course has a lot of similarities to the SV.
You can see how Eric does a CLA on and SV by a photo he sent me:
Attachment 121038
11-30-2012, 02:56 PM   #3
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Thank you for this information TomB from Texas. From this I see there is no easy adjustment that bypasses a CLA. That strip down picture of Eric's is why I stay away from dismantling when I don't know what I'm doing. Unfortunately the fellow here charges 2-1/2 times what Eric does, and when one has 35 film cameras, that can get expensive. Still, the information you gave is most helpful when I discuss sevicing, so thanks again.
12-01-2012, 02:37 PM   #4
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I will be sending one of these in for overhaul because a hair-spring that prevents the mirror from closing when one advances film, has either disconnected or broken.

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