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A850 Mirror Loose

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IanL View Drop Down
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Post Options Post Options   Quote IanL Quote  Post ReplyReply Direct Link To This Post Topic: A850 Mirror Loose
    Posted: 15 April 2022 at 21:00
The mirror has become loose from the "frame" which holds it. I cannot see any mechanical fastening to secure it in place - is it just glued in?

There are no camera repairers where I live (Jersey). If it is just glued in place, can anyone offer any advice - type of glue, precautions, etc?
Ian
 



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amozak View Drop Down
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Post Options Post Options   Quote amozak Quote  Post ReplyReply Direct Link To This Post Posted: 16 April 2022 at 03:30
If memory serves me well, which is debatable I seem to remember seeing a post about this problem before. I think it may have been on DPreview the A mount forum. There is a particular glue that the factory used to fasten the mirror in place. I think it's available for sale. Maybe do a search on this and see what comes up. Best of luck to you!
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Post Options Post Options   Quote addy landzaat Quote  Post ReplyReply Direct Link To This Post Posted: 16 April 2022 at 07:44
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IanL View Drop Down
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Post Options Post Options   Quote IanL Quote  Post ReplyReply Direct Link To This Post Posted: 16 April 2022 at 08:35
Thank you both for the prompt replies. In my ignorance, I though this would be an extremely rare problem, but regrettably not.

Reading about the failed repairs, I have opted for the recommended glue (Cemedine Super-X 8008 black) from Japan - £30 on EBay. The existing glue spots on the mirror feel slightly "soapy", so I fear this is a failed repair with the wrong glue, which may be difficult to remove. I'll post results.

EDIT: Reading the glue manufacturers website, it states the product is elastic and when hardened has a rubber state, so it may be the original glue. Whether to try to remove the original?

Edited by IanL - 16 April 2022 at 08:57
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addy landzaat View Drop Down
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Post Options Post Options   Quote addy landzaat Quote  Post ReplyReply Direct Link To This Post Posted: 16 April 2022 at 09:10
You might also google Yashica cameras with a similar problem. That camera had a sliding mirror also due to the kind of glue used. I have one that clears some lenses, but not all....
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IanL View Drop Down
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Post Options Post Options   Quote IanL Quote  Post ReplyReply Direct Link To This Post Posted: 02 June 2022 at 09:39
Update:

I decided to glue the mirror into place without dismantling the camera. The first difficulty was accurately positioning the mirror - the glue data suggested there would be only a short time to adjust position after application. I used a cut-off cotton swab tipped with two small pieces of masking tape as a positioning tool, and practiced a few times before applying the glue.

I removed the old glue from the back of the mirror, and some of the remains on the lower edge of the mounting frame, but I couldn't reach the top of the frame with my modelling knife, and I feared getting debris inside the mechanism or onto the sensor. I then appied a small dab of glue to each of the original four glued points with another swab, and placed the mirror into position (I thought).

The data suggests a seven day setting time for full strength, so I decided to put the camera into a plastic food bag and set aside for that length of time. My positioning tool was still attached to the mirror, and projecting out from the lens opening, and I needed it bent upwards slightly to clear the bag. When I applied pressure to do that, there was a loud click and a small movement, which I think was the mirror shifting into the correct position, so that was a stroke of luck!

Seven days later, I removed the positioning tool. I was a bit worried that pulling it away would overstress the glue, but the tape pulled away with virtually no resistance - perhaps the released gases from the glue acted as a release agent for the adhesive?

Powered the camera and attempted a shutter release, but the mirror scarcely twitched - that clicking into place must have squirted some glue and secured the frame to a non-moving part. I could see nothing, so in the end, I got another swab under the frame and levered upwards, more in hope than conviction.    

The glue is very resilient and allowed about twenty degrees of frame movement before it at last gave way, so that suggests the mirror will stay in place for a long time.

I have since done about forty shutter releases with no problems. Focus seems unimpaired, exposure spot-on even on the fastest shutter setting and I can't see any blemishes in the viewfinder from muck on the mirror, so I think its a success.

Edited by IanL - 02 June 2022 at 09:43
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amozak View Drop Down
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Post Options Post Options   Quote amozak Quote  Post ReplyReply Direct Link To This Post Posted: 02 June 2022 at 13:24
Wonderful news to hear the repair was a success! I'll make note of the glue that you used, just in case the mirror on my A900 ever has the same problem. Best regards....Art
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Post Options Post Options   Quote XKAES Quote  Post ReplyReply Direct Link To This Post Posted: 02 June 2022 at 13:44
Congratulations.
I hope it is a RARE problem, too.
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