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Classic Camera Repair » Archives-2005 » Petri Computor 35, need advice about resolving shutter malfunction « Previous Next »

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Scott

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Posted on Tuesday, November 01, 2005 - 08:32 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

I have a Petri Computor 35. The (electronic) shutter seems to work properly when the aperture ring is set to EE. On the EE setting, both the green and the yellow lamps light, depending on where I point the camera, and I can hear the difference in the shutter speeds. BUT...if I set the aperture ring to any of the aperture settings (from 2.8 to 22), I get only one shutter speed, no matter which ASA setting I set it at. So, if it's not set on EE, the only shutter speed I get sounds like it's about 1/30th or 1/15th of a second.

Any advice on what to look for when I try to fix it? thanks!
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WernerJB

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Posted on Tuesday, November 01, 2005 - 02:23 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

I do not know this particular camera, but if it is similar to the "Computor II" what you describe is the way it usually works, as the electronic shutter (Seiko-ESF, I guess) is always at that slow speed in the flash mode (sync for bulbs and electronic flashes). Are shutter opening times/ aperture openings correct when you operate the camera (with its back door open for inspection) when you expose it to different light sources in the EE mode?
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Winfried

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Posted on Tuesday, November 01, 2005 - 11:59 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

I have a manual for the Computor (and the camera itself), I will have a look later.
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Scott

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Posted on Wednesday, November 02, 2005 - 07:24 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

I don't have the "Computor II", but I believe it has somewhat more-advanced features than mine.

I did a quick search and saw a posting that says that this camera has an X-sync speed of 1/20th of a second.

http://www.pbase.com/cameras/petri/computor_35

On the EE setting, I get both the green and the yellow lights, depending on the how much light is hitting the camera. When the ring is moved from the EE setting to any of the f-stop settings (2.8 to 22), I get only the yellow light, and a single shutter speed, which sounds like it could be 1/20th/second.

Does that mean the camera thinks I have a flash mounted in the hotshoe, and has disabled the CdS metering system and put the camera into flash mode when not on the EE setting? I assume it should work much like my Yashica GSN when not set on EE.

I'm not so clumsy with the mechanical side of old cameras, but unfortunately I never learned how to test circuits properly.

I was envying the students in the high school this week where I teach English (in Taiwan). They all are required to take an "Elementary Circuits- Theory and Practice" class whether they want to or not, both boys and girls. I like to peep in and watch them soldering on their bread-boards. Actually, some of the things they're making don't look 'elementary', at all. I wish I had taken a class like that. Too bad they didn't offer it in my hometown!
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Scott

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Posted on Sunday, November 06, 2005 - 07:12 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

I don't have access to a manual, but it occurred to me that my Computor 35 might be working as it should.

I just assumed that because it has aperture settings (as well as the EE full-auto mode), that it should work in aperture-priority when set on an aperture setting, like a Yashica GSN, for example.

Mine is in such good condition, that it's hard to believe that it could be damaged in any way.

On EE setting, i get long or short shutter speeds, depending on the light and the ASA setting.

When set on any of the aperture settings (in other words, when not on the EE setting) I get the yellow 'lightning' flash symbol in the viewfinder and the same (sounds like 1/25 sec.) shutter speed regardless of the light conditions or the ASA setting.

Are those aperture settings there only for use with a flash?

Is there anyone with a manual who can check the specs?
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Winfried

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Posted on Monday, November 07, 2005 - 12:17 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

I have the Computor II which also has a Seiko ESF shutter. There is also a ring with 'guide number' markings (actually letters which have to be translated to guide numbers using a conversion table) and also aperture setting markings.

Believe it or not, but the manual does NOT mention anything about the manual aperture setting! It covers auto exposure and flash use, but says nothing about any manual setting, althought these seem to be possible.
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Winfried

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Posted on Monday, November 07, 2005 - 06:13 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

I found the aperture setting mentioned: The chapter about 'flash photography' says "When you use the automatic strobo (electronic flash, WB), follow the instruction book of your strobo to adjust the aperture".

It makes sense that the shutter is automatically set to a speed around 1/30 when selecting a manual aperture value for flash photography since this speed is required for old bulb flashes.
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Scott

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Posted on Monday, November 07, 2005 - 07:05 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Thanks, perhaps my Computor 35 has the same general functions and specs as the Computor II. Except the shutter on mine isn't marked Seiko (or anything else), and the lens is 1:2.8 f=40.

I'm assuming that it was only meant to be taken off of the EE setting when using a flash, and that the manual aperture settings were only meant to be used when using a flash.

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