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Jackson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 20, 2004 - 01:14 pm: | 
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Jon, I have uncovered the source of the foam that keeps falling on the focus screen. I think you need to add this into your instructions. See my link:
Nikon EM "Hidden" Foam
Can anyone help with this? I have no idea how to get at this foam. |
Jon Goodman
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 20, 2004 - 03:24 pm: |
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Hi, Jackson. I can not include instructions on how to repair that problem in the kit. You have to remove the pentaprism in order to get at this foam. Unfortunately, to do this successfully requires knowledge of electronic repair, experience with soldering very small circuits and is not in any form what I would describe as a good "do-it-yourself" project. There is far too much chance for catastrophic error. Here's why: Across the pentaprism...up one side and down the other, runs a transparent ribbon cable network with almost all the electronic "guts" attached to it. This cable is actually pretty tender (brittle may be a better word). It is easy to ruin, but not easy to fix. You must move all this circuitry out of the way, then replace it all. I just repaired one that showed evidence somebody had attempted to move one by prying up on it. There were 5 major breaks in the circuit as a result and evidently one I couldn't find. It took no small amount of work, and I was never able to make the little low light warning beeper operate again. If you want instructions on how to remove the top plate, I can post them, but please understand removing the prism is not going to be a cakewalk.
Jon |
Jon Goodman
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 20, 2004 - 03:30 pm: |
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Here is an example of what you'll have to remove. The EM is a little different, but not greatly...
https://kyp.hauslendale.com/classics/pentaxmeramblings.html
Jon |
Jackson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 20, 2004 - 05:00 pm: |
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OK, I do see the problem. Electronics service is (was) my field, and those mylar printed circuits are a major PITA. I agree, it wouldn't be useful to add instructions for this. Folks who don't do this for a living are extermely unlikely to be successful, and much more likely to ruin the camera.
So, what to do? It doesn't make sense to replace the foam everywhere by here. Let me ask a couple questions, just as food for thought.
First, do you know of any way to stabilize the existing foam? The foam in the rectangular frame doesn't appear to need flexibility in order to do its job. Maybe there's a way to use a small model brush to coat it with something that will dry hard and prevent bits from falling out.
Second, I wonder if it might be possible to simply push a length of square "spaghetti" foam into the groove along the rectangle without removing the old foam. Considering how gooey the old foam gets, maybe it will act like glue under the new stuff.
Bear in mind, I'm not saying either of these techniques are the right way to repair the camera. They're just "last resort" ideas so the thing can be used.
What do you think? |
Jon Goodman
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 20, 2004 - 07:08 pm: |
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Either approach might work, Jackson. Clear fingernail polish will stabilize the foam or a small piece of non-adhesive foam (as is provided in the kits I sell) pushed carefully into the seam will act as a dam, but the space is pretty shallow, and the foam might work out of the slot for that reason. How about an alternative? In the seal kit I sell is a very thin (1/32" or apx 1mm) closed cell foam which has a very strong adhesive. Why not slice thin strip strips of that and cover over the foam with it? Oh, drat. You didn't buy the kit, did you...hmmm, I suppose you could use Scotch transparent tape. Get the glossy one. It is more sticky. A mistake made with tape will be less problematic than fingernail polish, no?
Jon |
Jackson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 20, 2004 - 08:59 pm: |
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Yes, I'm think you're right about the fingernail polish. In fact, attempting to "set" the foam around this area by applying a liquid is probably too risky. One drop on the meter or the scale and it's all over.
I have some foam strip material that I usually use for the rear door channels. It's 1.75 x 2 mm. That might be too large for this application, but I'm not sure. It's open cell and very flexible, easy to compress. If I get time tomorrow, I'll clean out the old goop and see how it fits.
Believe me, i'll buy the large kit from you as soon as my current supply runs out. At this rate, that won't be too long. I have six cameras currently that need rear seals, and probably only enough material to do two.
Thanks for your advice on this. It's great to be able to discuss these things with someone knowledgeable.
Have a great weekend! |
jerry
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 05, 2005 - 10:57 pm: |
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I was wondering if RTV (dow corning fame) liquid
rubber might passivate this nasty rotton foam.
One would have to mask off all areas that need protection.
On the FE one can unscrew the Viewer and gently tip it back (no forcing) then place small wax paper or mylar in front of prism and the viewer to protect them . With access to this foam one can passivate it. apply a substance that will render it a monolythic block.
RTV is sticky but can be managed with care.
maybe in layers.
just a very thin layer.
just enough to stop the crumbling , then stop.
There is got to be a simple and easy technique to do this job. I am just thinking out load and hope other can come up with even better ideas.
jerry |
Jon Goodman
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 06, 2005 - 06:23 am: |
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It might work, Jerry. The problem is available space in which to work v the product you're using. Given the challenges, I've decided it is probably best to remove the focus screen every 4 to 6 months and simply wash it off.
Jon |
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